UP3.1 | Climate change detection, assessment of trends, variability and extremes

Society will feel the impacts of climate change mainly through extreme weather and climate events, such as heat waves and droughts, heavy rainfall and associated flooding, and extreme winds. Determining from the observational record whether there have been significant changes in the frequency, amplitude and persistence of extreme events poses considerable challenges. Changes in the distributional tails of climate variables may not necessarily be coherent with the changes in their mean values. Also, attributing any such changes to natural or anthropogenic drivers is a challenge.

The aim of this session will be studies that bridge the spatial scales and reach the timescales of extreme events that impact all our lives. Papers are solicited on advancing the understanding of causes of observed changes in mean climate, in its variability and in the frequency and intensity of extreme events. In particular, papers are invited on trends in the regional climate of Europe, not just the mean, but variability and extremes, often for the latter measured through well-chosen indices.

Including Tromp Foundation Travel Award to Young Scientists
Convener: Martine Rebetez | Co-conveners: Albert M.G. Klein Tank, Monika Lakatos, Gudrun Nina Petersen
Orals
| Thu, 07 Sep, 11:00–16:00 (CEST)|Lecture room B1.02, Fri, 08 Sep, 09:00–12:30 (CEST)|Lecture room B1.02
Posters
| Attendance Thu, 07 Sep, 16:00–17:15 (CEST) | Display Wed, 06 Sep, 10:00–Fri, 08 Sep, 13:00|Poster area 'Day room'
Orals |
Thu, 11:00
Thu, 16:00

Orals: Thu, 7 Sep | Lecture room B1.02

Chairpersons: Martine Rebetez, Albert M.G. Klein Tank
Precipitation and drought
11:00–11:30
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EMS2023-45
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UP3.1
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solicited
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Online presentation
Olivia Martius, Christoph von Matt, Lukas Gudmundsson, and Regula Muelchi

Periods with very low discharge, anomalously low precipitation or anomalously low soil moisture content are all considered droughts, although different types. The differentiation is relevant from an impact perspective. For example, low discharge (hydrological drought) is challenging for transportation and fish, low precipitation (meteorological drought) is challenging for energy production and agriculture, and low soil moisture for agriculture and soil subsidence. If the different types of droughts occur simultaneously impacts may compound, e.g. if discharge is low irrigation water can no longer be taken from rivers.

We quantify the co-occurrence of the three different drought types in Switzerland in the extended summer season under current and future climate conditions using the Swiss climate change scenarios (CH2018, CH2018-hydro). These scenarios are a set of 44 GCM-RCM model chains based on CMIP5. Temperature and precipitation information from these scenarios is then used to run a hydrological model for more than 80 catchments in Switzerland to generate discharge time-series but select only catchments that are not strongly influenced by glaciers and snow melt.

Compound drought days are prevalent under current climate conditions both north and south of the Alps (on average more than 3 days per year).  Compound drought days tend to affect several catchments across the country at the same time and the simultaneously affected area increases with climate change. We find a significant and substantial (more than a doubling) increase in the number of compound drought days in all catchments both north and south of the Alps under RCP8.5 forcing conditions. Under an effective mitigation forcing (RCP2.6) the increase is not significant.

How to cite: Martius, O., von Matt, C., Gudmundsson, L., and Muelchi, R.: Compound droughts in Switzerland under current and future climate, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-45, https://doi.org/10.5194/ems2023-45, 2023.

11:30–11:45
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EMS2023-228
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UP3.1
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Onsite presentation
Pavel Zahradníček, Rudolf Brázdil, Jan Řehoř, Lukáš Dolák, and Miroslav Trnka

Heat waves represent meteorological phenomena with serious impacts on human society and environment. Coincidence of their increased occurrence and intensity with increased frequency and severity of the summer drought episodes in the Czech Republic, particularly in the last decade of the 2010s and early 2020s calls for the study of their long-term spatiotemporal variability and compound effects. As an example serve the year 2015, when the Czech Republic experienced a record number of hot days and during July and August the soil moisture was very low. Our analysis of these effects and relationships is based on homogenised data of climatological stations of the Czech Hydrometeorological Institute and on soil moisture outputs coming from calculations of the SoilClim water-balance model for the 1961–2022 period. Different methods of statistical analysis are used to find changes in long-term fluctuations, trends, severity and spatial features of heat waves and soil droughts over the territory of the Czech Republic. Anticyclonic, cyclonic and directional circulation types derived from objective classification taken in account flow strength, flow direction and vorticity are used to investigate possible drivers of related changes in both heat waves and soil droughts and their spatiotemporal relationships. It is also tested whether a stronger relationship exists between soil moisture and heat waves represented by at least three consecutive days with a maximum temperature above 30°C or defined by a certain percentile threshold (e.g., 90 or 95%). Results obtained are discussed with respect to their impacts on the occurrence of wildfires and numbers of related fatalities and injures in the Czech Republic as well as in the context of a broader European scale.

How to cite: Zahradníček, P., Brázdil, R., Řehoř, J., Dolák, L., and Trnka, M.: Relationships between heat waves and soil drought in the Czech Republic, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-228, https://doi.org/10.5194/ems2023-228, 2023.

11:45–12:00
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EMS2023-226
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UP3.1
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Onsite presentation
Ivan Loncar-Petrinjak, Zoran Pasaric, and Ksenija Cindric Kalin

Several droughts during the last decade seriously affected large parts of Europe, including Croatia, causing significant economic losses, particularly in the agriculture and energy sectors. Though rainfall is the main driver of drought, high temperatures during summer months may intensify its development with devastating consequences. Such was the case in 2022 when long dry spells were accompanied by several heat waves. In this study, climatological drought monitoring with the Standardized Precipitation-Evapotranspiration index (SPEI) was analysed with the primary aim of finding the best theoretical distribution for fitting the water balance in Croatia before implementing the index in the official operational procedure for drought monitoring. Monthly precipitation amounts and air temperature values were employed at 31 main meteorological stations for the period 1961-2022 and the water balance (defined as a difference between precipitation and potential evapotranspiration) was calculated for different time scales (1 - 24 months). Among five selected distributions, a three-parameter generalized logistic (GLO) distribution was found as the most appropriate one. There is a general agreement between SPEI and SPI time series, both in sign and intensity of droughts. However, a tendency toward higher drought intensity prevailed with the SPEI, particularly in periods with a light to moderate lack of precipitation and high air temperature. Comparison in precipitation and water balance in the two reference climate periods (1961-1990 and 1991-2020) revealed: a consistent trend toward drying conditions from March to August; an increase in the frequency of dry spells; and a tendency toward longer dry spells (for time scales up to 9 months). A comparative analysis of the 2022 drought in Croatia confirmed the ability of SPEI to detect drought earlier than the SPI, also suggesting that a larger area of the country was affected by drought due to high-temperature anomalies.

How to cite: Loncar-Petrinjak, I., Pasaric, Z., and Cindric Kalin, K.: Drought monitoring in Croatia using the Standardized Precipitation-Evapotranspiration Index, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-226, https://doi.org/10.5194/ems2023-226, 2023.

12:00–12:15
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EMS2023-496
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UP3.1
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Onsite presentation
Vicent Altava-Ortiz, Mercè Barnolas, and Antoni Barrera-Escoda

Catalonia is currently affected by a severe drought episode which is reporting unrecorded impacts in most part of the country. It is well known that precipitation presents a high temporal variability in the Mediterranean climate. Consequently, drought episodes are frequent, and they are an intrinsic characteristic of this type of climate. However, drought events are showing a higher frequency during the last few decades.

In this work we have studied drought and pluvial episodes derived from the calculation of the Standardized Precipitation Index (SPI) in Catalonia during the instrumental period 1915-2022. Series of precipitation aggregated at 12 and 72 months, lead to a first approximation for temporal variability of drought and pluvial events at high and low frequency, respectively. From the temporal evolution of the SPI-12, it is derived that the frequency of dry(wet) episodes has increased(decreased) in recent decades (statistically significant). This behaviour is observed in all Catalan hydrological catchments. The increase in the drought frequency is also corroborated when analysing the SPI-72 dry/wet area time series. The SPI-72 signal also reveals that the natural transition between pluvial and drought periods (and vice versa) has been broken since the 1980s, with domination of droughts since then. From the total number of drought episodes, two of them emerge: the 2004-2008 event and the current 2021-2023 drought episode. Depending on the analysed basin, one of these events can be considered the most severe one ever recorded in Catalonia since 1915.

In fact, the severity of the current event has motivated the creation of a new drought severity index (DSI), which considers the pick, mean intensity, duration and extension of the drought area. In the context of climate change, this index is called to be useful to rank future drought episodes when compared with historical ones.      

How to cite: Altava-Ortiz, V., Barnolas, M., and Barrera-Escoda, A.: Characterisation and temporal evolution (1915-2022) of drought and pluvial periods in Catalonia, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-496, https://doi.org/10.5194/ems2023-496, 2023.

12:15–12:30
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EMS2023-173
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UP3.1
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Onsite presentation
Beatriz Fernández-Duque, Sergio M. Vicente-Serrano, Oswaldo Maynard, Fernando Domínguez-Castro, Dhais Peña-Angulo, Iván Noguera, César Azorín-Molina, and Ahmed El Kenawy

Mountainous and highland regions are among the most sensitive and vulnerable areas to climate change and to its impacts since these ecosystems support a remarkable level of biodiversity. Small changes in temperature and precipitation with altitude could have major habitat implications for animal and plant species living in upper mountain environments leading to important social and economic consequences. However, although some authors pointed out a faster warming at highland elevation than the global average it is still unclear whether the trend of different climatic variables has an altitude dependence or not. We present a long-term assessment of temperature, relative humidity and vapor pressure deficit data over the whole Bolivia for the period 1961–2021 using in-situ observationsat different elevation ranges over a gradient of more than 4000 meters. The analysis shows statistically significant increments of the mean (0.17ºC decade-1), the maximum (0.16ºC decade-1) and the minimum temperature (0.17ºC decade-1) records over the whole study period. The relative humidity trend reflects a slightly decrease (-0.08% decade-1) although it was not statistically significant. Besides, the vapor pressure deficit data display an increment of 0.01 hPa decade-1 (p < 0.05). Contrary to previous studies based on shorter records, we detected by using long-term and quality controlled series no statistically significant relationship among the trend in the climatic variables analyzed and the altitude. Just an inverse and statistically significant relationship for the minimum temperatures and altitude was found for the dataset during the warm season but the opposite is found when considering the maximum temperatures during the cold season. This study contributes to understand climate processes in complex topographic areas of South America, which are poorly studied up to date.

Keywords:climatic variables, altitude dependence, in-situ observations, trends, South America.

 

How to cite: Fernández-Duque, B., Vicente-Serrano, S. M., Maynard, O., Domínguez-Castro, F., Peña-Angulo, D., Noguera, I., Azorín-Molina, C., and El Kenawy, A.: Long-term temperature, relative humidity and vapor pressure deficit trends in Bolivia, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-173, https://doi.org/10.5194/ems2023-173, 2023.

12:30–12:45
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EMS2023-560
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UP3.1
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Onsite presentation
Monika Lakatos, Olivér Szentes, Beatrix Izsák, Kinga Bokros, and Zita Bihari

The warming climate evokes increasing frequency of extreme precipitation in some region. Better understanding of the processes that cause extreme precipitation events under the current climate could support the climate model simulations. The investigation of the sub-daily precipitation can help understanding of the nature and drivers of precipitation extremes.

Automatic stations replaced the ombrometers in many places in Hungary particularly from the late 1990s. According to the recent practice the 10 min precipitation data are stored at the meteorological database at the Hungarian Meteorological Service. In a recent a project we have possibility to digitize ombrometer registering papers. We decided to enter the 10 min sums from the registering paper as it could have been measured by the automatic weather station. As a result of the digitization process 10 in rainfall depth for five stations will be available for trend analysis to detect changes from the first half of the early 20th century.

A set of hydroclimatic indices on 1-hour sum have been defined in the INTENSE project is in correspondence with the World Climate Research Programme (WCRP)'s Grand Challenge on 'Understanding and Predicting Weather and Climate Extremes' and the Global Water and Energy Exchanges Project (GEWEX) Science questions. Some of the indices defined in INTENSE and implemented in INDICES computer program developed at Newcastle University describes the maximum rainfall totals and timing, the intensity, duration and frequency of heavy precipitation, frequency of rainfall above specific thresholds and some of them is related to diurnal cycle. A few of these indices are analysed for Hungary in this work. We also refer for the joint effort in the recent past in the Carpathian Basin focusing on the change of the sub-daily precipitation extremes (Lakatos et al., 2021).

Lakatos, M.; Szentes, O.; Cindrić Kalin, K.; Nimac, I.; Kozjek, K.; Cheval, S.; Dumitrescu, A.; Irașoc, A.; Stepanek, P.; Farda, A.; Kajaba, P.; Mikulová, K.; Mihic, D.; Petrovic, P.; Chimani, B.; Pritchard, D. Analysis of Sub-Daily Precipitation for the PannEx Region. Atmosphere 2021, 12, 838. https://doi.org/10.3390/atmos12070838

Acknowledgements:

The research presented was carried out within the framework of the Széchenyi Plan Plus program with the support of the RRF-2.3.1-21-2022-00014 National Multidisciplinary Laboratory for Climate Change project.

How to cite: Lakatos, M., Szentes, O., Izsák, B., Bokros, K., and Bihari, Z.: Long term changes of the sub-daily precipitation extremes in the Carpathian basin, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-560, https://doi.org/10.5194/ems2023-560, 2023.

Snow
12:45–13:00
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EMS2023-581
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UP3.1
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Onsite presentation
Agnieszka Wypych, Zbigniew Ustrnul, and Julia Sałaja

Mountainous areas are uniquely susceptible to climate change, making them good indicators of these changes. Research results from different parts of the world indicate recent warming of mountainous regions, particularly located since the 1980s, with different intensity in particular vertical zones. Temperature growth is not followed by significant trends in annual precipitation totals however it brings the change in precipitation annual structure and types what influences the occurrence and persistence of snow cover.

As snow cover is a key element of the Earth’s system with the impact on hydrology, climate, and ecological environment any changes in snowpack patterns will have a complex effect. The aim of the study is to examine the variability of snow cover variables (snow depth and snow cover duration) and they sensitivity to the main atmospherical drivers (temperature and precipitation) including inter-annual variations, and trends over various time scales.

The research has been conducted for mountain areas in Central Europe, defined as the terrain with the elevation above 500 m a.s.l. in the domain of 5°E - 25°E and 47°N-55°N. The analyses cover the period 1981-2022 and are based on various meteorological data sources, i.e. in-situ snow depth observations and near ground temperature and precipitation measurements (serving as reference data) as well as regional reanalysis ERA5-Land and CERRA-Land.

The primarily research results confirm the significant impact of temperature and precipitation change on snow cover characteristics with the differentiation of its intensity dependent on geographical and terrain variables as the altitude, landform, slope and exposition. Nevertheless multiannual variability of snowpack persistence with its decreasing trend over the whole research area has been observed.

Detailed understanding of the timing of snow accumulation and snow ablation is necessary as it controls the mountain runoff rate during the spring, water infiltration and groundwater storage as well as the transpiration rate, crucial elements of hydrological cycle.

How to cite: Wypych, A., Ustrnul, Z., and Sałaja, J.: Snow cover response to temperature and precipitation variability in Central European mountain ranges, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-581, https://doi.org/10.5194/ems2023-581, 2023.

Lunch break
Chairpersons: Martine Rebetez, Albert M.G. Klein Tank
Temperature
14:00–14:15
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EMS2023-70
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UP3.1
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solicited
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Onsite presentation
Radan Huth and Tomáš Krauskopf

Substantial efforts have been made in climatic analyses of climate means and extremes, while much less has been done in understanding short-term (intraseasonal and synoptic-scale) variability. One particular aspect of short-term atmospheric variability is day-to-day temperature difference (DTD). Large DTDs negatively affect human health and impact also animals and plants, hence constituting one of the many weather-related risks to society.

In this contribution, we present European climatology of DTD, including its higher statistical moments and behaviour in distribution tails, in a variety of datasets (observations – ECA&D, gridded observed datasets – E-OBS, reanalyses – NCEP/NCAR, JRA-55, 20CR). The magnitude of DTD is – quite expectedly – largest in winter and smallest in summer, and increases from the coast to the continental interior. Skewness of DTD is negative (i.e., large temperature drops prevail over large temperature rises and/or small temperature rises prevail over small temperature drops) over most of Europe in summer, while in the other seasons, there is a tendency for positive skewness to occur in the north and for negative skewness to occur in the south and over the British Isles. Kurtosis of DTD is everywhere and in all seasons larger than Gaussian; i.e., DTD distributions have heavy tails. Comparisons among datasets reveal their specific deficiencies, such as the existence of outlying unrealistic temperature values in station data that are undetected by quality check, the underestimation of the magnitude of DTD particularly by the 20CR reanalysis, and overestimated skewness in the British Isles in winter and in teh Mediterranean in summer by all reanalyses.

How to cite: Huth, R. and Krauskopf, T.: European climatology of day-to-day temperature changes, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-70, https://doi.org/10.5194/ems2023-70, 2023.

Impacts
14:15–14:30
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EMS2023-338
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UP3.1
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Online presentation
André Fonseca, Cristina Andrade, André Claro, Hélder Fraga, and João A. Santos

Grape berries and their yields can be strongly affected by the complex connections and interactions between the grapevines and the conditions of the local environment. In areas of known wine production, the yield and quality are usually improved by considering the climate, planting the best grape variety, and using specific agricultural techniques. Thus, sustainability in the winemaking sector worldwide is under pressure due to ongoing climate change, requiring adaptation at multiple levels. Portuguese vineyards will experience increasingly dry and warm conditions due to climate change, with varying degrees of intensity and frequency of weather extremes. Nevertheless, the potential effects of these extraordinary occasions and their effects on viticulture in the future are not well known. In this research, we calculated seventeen climate extreme indices for the Portuguese wine denomination of origin regions/subregions in the historical period (1981–2010) and future periods (2041–2070 and 2071–2100), under the Representative Concentration Pathway 8.5, and based on a five-member ensemble of Regional Climate Model-Global Climate Model chain simulations. Moreover, a principal component analysis was performed for both precipitation and temperature extremes independent of each other. All of Portugal's wine regions experienced an increase in temperature extremes, predominantly in the westernmost regions. When it comes to the precipitation extremes, they show a decrease in the future and a general decline in precipitation but still are a major risk in the northeastern regions. In contrast, the dry extremes, likely bringing on severe droughts, will become much stronger. Finally, it was then possible to recognize which wine regions will be the most vulnerable to extreme weather conditions in the future. This information is essential for enabling smarter choices in the sector, including for long-term planning, climate change adaptation and risk reduction.

Acknowledgments: Soil recover for a healthy food and quality of life (SoilRec4+Health). Projeto cofinanciado pelo Fundo Europeu de Desenvolvimento Regional (FEDER) através do Programa Operacional Regional do Norte (NORTE-01-0145-FEDER-000083).

How to cite: Fonseca, A., Andrade, C., Claro, A., Fraga, H., and A. Santos, J.: Future exposure of Portuguese viticulture to weather extremes, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-338, https://doi.org/10.5194/ems2023-338, 2023.

14:30–14:45
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EMS2023-443
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UP3.1
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Onsite presentation
Zala Žnidaršič, Gregor Gregorič, Andreja Sušnik, and Tjaša Pogačar

Sweet cherry (Prunus avium L.) is an important fruit tree for Slovenia, often threatened by spring frosts, especially the early flowering varieties. In recent decades, the occurrence of frost events has steadily increased, which has negatively affected cherry fruit production, especially in the Submediterranean part of Slovenia. Although fruit trees can tolerate severe cold during their dormant stage, the resistance of flower buds gradually decreases with phenological development in spring. Therefore, spring frost events that occur after the beginning of the growing season pose a major risk to fruit trees. An analysis of the probability of frost events in Slovenian cherry orchards was performed based on historical temperature data from the E- OBS database and climate model projections, in particular regionally downscaled EURO-CORDEX projections (ensemble of 6 models) for scenarios RCP4.5 and RCP8.5. The presented analysis is based on two phenological models for calculation of budburst - the growing degree days (GDD) model and the BRIN model. The projections showed an overall increase in frost risk for the majority of models and all selected sweet cherry varieties during the periods 2011–2040 and 2041–2071 compared to the reference period 1981–2010. For the end of the century (period 2071–2100), all of the ensemble projections showed a large increase in frost risk for the analyzed sweet cherry varieties. The projected increase in frost risk under the RCP4.5 scenario was calculated to be the highest for the Early Bigi variety, while under the RCP8.5 scenario the largest increase was calculated for the Germersdorf variety - a more than 40-fold increase in spring frost risk compared to the reference period.

How to cite: Žnidaršič, Z., Gregorič, G., Sušnik, A., and Pogačar, T.: Frost risk climate change projections for sweet cherry (Prunus avium L.) in Slovenia, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-443, https://doi.org/10.5194/ems2023-443, 2023.

14:45–15:00
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EMS2023-239
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UP3.1
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Tromp Foundation Travel Award to Young Scientists
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Onsite presentation
Nestoras Antoniou, Hamid Montazeri, Bert Blocken, and Marina Neophytou

As a result of climate change, projections show that the increasing urban population will be exposed to higher air temperatures (Hayes et al., 2014; Sheffield and Wood, 2008). In addition, due to climatic changes, the frequency and duration of heatwaves are expected to increase while the Urban Heat Island effect (UHI) is expected to become more severe (Emmanuel and Krüger, 2012; Kovats and Hajat, 2008; Mirzaei and Haghighat, 2010), causing increasing heat-related mortality and morbidity (Garssen et al., 2005; Xu et al., 2012). Meditteranean-type climate regions have been characterized as particularly vulnerable to climate change due to their high exposure to extreme weather phenomena (Diffenbaugh and Giorgi, 2012; Paz et al., 2016). The intensity of heat waves in these regions is expected to increase further, leading to other life-threatening consequences for urban populations in the Mediterranean region  (Legasa et al., 2020; Zittis et al., 2021). Under this context, the detailed investigation of the impact of climate change on the urban microclimate and human health is considered highly important. This study investigates the impact of climate change on urban microclimate and pedestrian thermal comfort through a series of numerical simulations. For this purpose, 3D Computational Fluid Dynamics (CFD) simulations are performed based on the Unsteady Raynolds-Average Navier-Stokes (URANS) equations for urban microclimate in a real compact heterogeneous urban area. The CFD validation is based on high-resolution field and laboratory measurements of the case study area in Nicosia, Cyprus (Antoniou et al., 2019, 2017). Simulations are performed for meteorological conditions based on field measurements performed in 2010, and for predicted meteorological conditions for 2050 derived from downscaled Regional Climate Models (RCMs). The RCM data are derived from the European Coordinate Regional Downscaling Experiment (EURO-CORDEX) database. CFD results are combined with radiation modeling results of the same urban area to calculate pedestrian thermal comfort using the Universal Thermal Comfort Index (UTCI). The results show that by 2050, a 2.3 °C  increase in the maximum air temperature is expected to occur, which can lead to a more than 240% increase in heat-related mortality. In addition, an increase of UTCI levels is also expected, which is more pronounced in the late afternoon hours, reaching up to 4.3 °C increase at 20:00. A significant change in the thermal stress categories is also identified between the 2010 and 2050 scenarios, where “very strong heat stress” conditions (UTCI: 38-46 °C) are expected to prevail for twice as long, increasing from 3.3 to 6.6 hours, and  “extreme heat stress” conditions (UTCI > 46 °C) appear at some locations of the area in 2050.

 

 

How to cite: Antoniou, N., Montazeri, H., Blocken, B., and Neophytou, M.: Multiscale numerical simulations of climate change impact on urban microclimate and human health, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-239, https://doi.org/10.5194/ems2023-239, 2023.

Wind
15:00–15:15
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EMS2023-342
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UP3.1
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Online presentation
André Claro, João A. Santos, Cristina Andrade, and David Carvalho

Wind energy fluxes over Portugal and the nearby Atlantic Ocean were estimated under an IPCC future socioeconomic scenario (IPCC SSP5-8.5) for the 2046–2065 and 2081–2100 periods, using wind speed data from WRF 6 km regional simulations. CMIP6 (Coupled Model Intercomparison Project) global model ensemble simulations were also used to assess future anomalies in the Euro-Atlantic large-scale circulation, through kinetic energy and sea level pressure data. Projections show a winter southward displacement of the mid-latitude jetstream, along with a northward displacement during spring, summer, and autumn, which leads to a summer strengthening of the northern winds along the northwestern Iberian coast. Moreover, offshore the northwest coast of Portugal and in the Serra da Estrela mountain range, a 25% to 50% increase in the summer wind power density (WPD) should occur in 2046–2065, and up to more than 100% in 2081–2100. This is also seen in the CMIP6 global projections. In 2046–2065, the WPD’s daily variability and extreme values should increase offshore northwestern Portugal during winter, spring and summer. During autumn, extreme WPD event intensity should decrease. Furthermore, the WPD’s inter-annual variability should increase offshore the northwest coast, and decrease along the central western and southern coasts.

 

Acknowledgments:

This work was co-funded by FEDER (European Fund for Regional Development), under the project ATLANTIDA – Platform for the monitoring of the North Atlantic Ocean and tools for the sustainable exploitation of the marine resources (NORTE-01-0145-FEDER-000040). This work was also funded by National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UIDB/04033/2020.

How to cite: Claro, A., A. Santos, J., Andrade, C., and Carvalho, D.: Projections of wind energy potential in Portugal assessed with CMIP6 simulations, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-342, https://doi.org/10.5194/ems2023-342, 2023.

15:15–15:30
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EMS2023-425
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UP3.1
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Online presentation
Miguel Andrés-Martín, César Azorín-Molina, Sergio M. Vicente-Serrano, Shalenys Bedoya-Valestt, Eduardo Utrabo-Carazo, and Nuria P. Plaza Martín

Near-surface wind speed (SWS) has been the forgotten part of the climate system, compared with other viables as temperature or precipitation, due to poor quality of observational data and the challenges in the homogenization process. During the last two decades the interest in long-term SWS variability and trends has increased and two main phenomena were discovered using observational data: the first one is termed “stilling” (decline until the 2010s), followed by the “reversal” (increase since then) of SWS. For a complete characterization of SWS changes, extremes also need to be evaluated as they have wide socioeconomic and environmental implications. The majority of the studies dealing with wind extremes are focused on high wind speeds associated with extratropical cyclones, hurricanes, tornados, storms, etc., which represent a threat for human lives and cause large damages. However, low wind speed events (known as “wind droughts”) have received less attention, representing a research gap in climate studies, and they are crucial due to the strong impacts on, for example, wind power generation a key motor of decarbonization. The main objective of this study is to define a Wind Drought Index (WDI) to identify and quantify the magnitude and extend of low wind speed events over the Iberian Peninsula. Our analyses are based on quality controlled and homogenized observational data series from 86 stations over Spain and Portugal for 1961-2022. Here we present for the first time the long-term and spatio-temporal changes in the occurrence and intensity of wind drought events over the study region.

How to cite: Andrés-Martín, M., Azorín-Molina, C., Vicente-Serrano, S. M., Bedoya-Valestt, S., Utrabo-Carazo, E., and Plaza Martín, N. P.: Wind Drought Index: a proposal to assess low wind speed events over the Iberian Peninsula, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-425, https://doi.org/10.5194/ems2023-425, 2023.

Methods and mechanisms
15:30–15:45
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EMS2023-58
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UP3.1
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Onsite presentation
Yavor Chapanov

The Arctic Oscillations (AO) are connected with various regional and global climatic events. These oscillations are important to study recent climate change and to improve our knowledge about the dynamics of climatic disasters. The main sources of these oscillations are the influences of global warming, solar activity and cosmic rays on climatic variations. The solar activity affects climatic processes by the Total Solar Irradiance (TSI) variations, solar wind and solar magnetic field. The variations of solar magnetic field are connected with the asymmetrical distribution of sunspots around the solar equator. These variations modulate heliosphere, geomagnetic field and galactic cosmic rays, whose influence on climate oscillations depends on ozone production in high latitudes. The solar influence on Arctic Oscillations are analyzed by centennial time series of TSI and North-South (N-S) solar asymmetry. The time series of Arctic Oscillation since 1850 are combined by data, prepared by David W. J. Thompson with the data from the NCEP/NCAR Reanalysis after 1958. The combined Arctic long time series are analyzed by the Method of Partial Fourier Approximation (PFA) and compared with solar cycles in several narrow frequency bands. In addition, time series from 20th Century Reanalysis V3 dataset of surface monthly means air temperature inside the North polar circle are analyzed and compared with solar data. Various common solar and atmosphere cycles in narrow frequency bands are detected, whose periodicity is between 3 and 80 years. The mean variations of atmosphere data are determined by averaging in moving 2-year window. The AO and temperature time series have positive trends after 1960, where the rate of temperature rise is 0.107 degree per year since 1988. The solar influence on AO variations is dominated by the N-S solar asymmetry, and this points out to the important role of cosmic rays and geomagnetic field on climatic cycles. These results can help to divide natural solar from anthropogenic effect in recent global warming and to improve scenario of future climate change.

How to cite: Chapanov, Y.: Solar influence on Arctic Oscillations, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-58, https://doi.org/10.5194/ems2023-58, 2023.

15:45–16:00
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EMS2023-336
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UP3.1
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Onsite presentation
Cristina Andrade, João A. Santos, and André Fonseca

Climate strongly influences not only the distribution and abundance of species on Earth but also the distribution of ecosystem types. Since the climate is defined as a long-term pattern of weather conditions at a given location or region both the distribution and evolution of its conditions are considered highly relevant. The Köppen-Geiger climate classification is based on temperature and precipitation and has been widely used to assess climate shifts worldwide.

In this study, high spatial resolution (10 min) monthly precipitation (in mm) and maximum, minimum, and mean temperatures (in °C) gridded datasets were retrieved from the WorldClim data website. The Köppen-Geiger climate classification was then computed worldwide between 1970 and 2000 (historical baseline) and between 2041 and 2060 under two Shared Socio-economic Pathways (SSPs) SSP2‒2.6 and SSP5‒8.5; from an ensemble of 14 Global Climate Models (GCMs).

Results point out an overall decrease of type E (Polar) around 4.6% for ET (Tundra) and 3.8% for EF (Icecap) under both SSPs. A noticeable decrease of type Dfc (Temperate subpolar oceanic) 7.34% and 7.53% under SSP2-2.6 and SSP5-8.5, respectively is also projected. Climate types Csa (Temperate with hot summer) and Cfb (Temperate oceanic with warm summer) are also projected to decrease by about 1% under both SSPs. Conversely, in decreased order of magnitude, types Dfa (Continental humid with hot summer, 6%), Cfa (Temperate humid subtropical, 2.8 and 2.9%), BWh (Hot desert, 1.4%), BSh (Hot semi-arid or steppe, 1.3%), As (Tropical, 1.2%), Dwa (Monsoon-influenced hot-summer humid continental, 1%) are projected to increase under SSP2‒2.6 and SSP5‒8.5, respectively. The projected changes mainly in locations like Siberia (reduction of type E areas, for example), will have a detrimental effect on the environment since the melting of the permafrost will release methane a powerful greenhouse gas, thus contributing to global warming.

 

Acknowledgments: This research was funded by National Funds by FCT ‒ Portuguese Foundation for Science and Technology, under the project UIDB/04033/2020.

How to cite: Andrade, C., A. Santos, J., and Fonseca, A.: Worldwide Köppen Geiger Climate classification changes projections (SSP2-2.6 and SSP5-8.5), EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-336, https://doi.org/10.5194/ems2023-336, 2023.

Orals: Fri, 8 Sep | Lecture room B1.02

Chairpersons: Monika Lakatos, Gudrun Nina Petersen
09:00–09:15
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EMS2023-304
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UP3.1
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Online presentation
Helge Goessling

Climate is defined by the statistics of the weather. We are thus used to the notion that weather depends on climate in the sense that a weather state is a quasi-random realization drawn from the climatological distribution of weather states. Consequently, weather obviously also depends on climate change. Here it is argued that it can be very instructive to consider this dependence the other way around and to investigate how climate change depends on the weather. More specifically, the question is how different parts of the climatological distribution change, depending on certain relevant characteristics of the weather. For example, one may ask how the climate at some time of the year and at some location changes between a pre-industrial and a globally +4K warmer climate, considering only days where the local winds at some height blow from a specific direction. Alternatively, one may investigate how the climate change pattern differs between certain large-scale atmospheric circulation regimes, such as NAO+ and NAO- situations. While such conditional climate change analyses can be based for example on reanalysis or CMIP-type climate model data, a more extreme variant are storyline simulations where the evolution of the large-scale circulation is imposed in a climate model using different climate backgrounds, allowing to assess climate change conditional on a specific evolution of the large-scale circulation. Storyline simulations inevitably ignore possible changes in the likelihood of circulation patters. In contrast, analyses based on sufficiently large samples of reanalysis or CMIP-type data also allow for quantifying changes in likelihoods and constitute a proper decomposition of the complete (unconditional) climate change signal. Here the concept of weather-dependent climate change is described and its potential to help unravel the complexities of climate change is demonstrated.

How to cite: Goessling, H.: Weather-dependent climate change, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-304, https://doi.org/10.5194/ems2023-304, 2023.

09:15–09:30
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EMS2023-196
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UP3.1
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Onsite presentation
Bijan Fallah, Emmanuele Russo, Christoph Menz, Peter Hoffmann, Iulii Didovets, and Fred F. Hattermann

Bias-adjusted and downscaled climate data are essential for regional impact studies. In some cases, a “counterfactual” baseline climate data that isolates the human-induced influences is also required for impact studies that focus on the anthropogenic influence. We examine how human activities have influenced the frequency and intensity of extreme temperature and precipitation events in Central Asia (CA) from 1960 to 2014. We use two sets of simulations from six climate models that are part of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) and the Coupled Model Inter-comparison Project phase 6 (CMIP6). One set (labelled as hist-nat) includes only natural factors (solar and volcanic activity) and the other set (labelled as hist) includes both natural and human factors (such as greenhouse gas emissions). We bias-correct and statistically downscale these simulations using the Climatologies at high resolution for the earth’s land surface areas dataset (CHELSA) to a finer spatial resolution (0.25°× 0.25°) to better capture the regional climate variability and impacts. We find that human factors have increased the risk of extreme heat events by four times across most of CA in the hist simulations compared to the hist-nat simulations. We also find that human factors have enhanced the likelihood and magnitude of extreme precipitation events over CA in the hist simulations, especially over Kyrgyzstan and Tajikistan, where landslides and floods are common hazards. Our results suggest that human-induced climate change has contributed to more severe weather extremes over vulnerable regions of CA. Our high-resolution data set is publicly available and can be used for further studies on the causes and consequences of extreme events in CA.

How to cite: Fallah, B., Russo, E., Menz, C., Hoffmann, P., Didovets, I., and Hattermann, F. F.: The Human Factor: Increasing the Risk of Weather Extremes in Central Asia, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-196, https://doi.org/10.5194/ems2023-196, 2023.

09:30–09:45
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EMS2023-209
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UP3.1
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Onsite presentation
David Carvalho, Amal El Akkraoui, Ronald M. Errico, Michael Bosilovich, and Nikki C. Privé
Due to the enormous computational costs of producing reanalyses, it has become common practice to split the reanalysis production into multiple, parallel computational streams that usually include some year-long periods of overlap to account for the necessary spin-up integration period of each stream and foster continuity between successive streams. A fundamental assumption underlying the use of parallel NWP-DAS computational streams is that they will eventually converge to a common atmospheric state in a relatively short period of time. This important expectation of convergence has very limited investigation, and this study presents a more in depth analysis on this question.
 
Differences between reanalyses valid at the same times but produced by different streams were determined using overlapping periods from NASA’s GMAO MERRA-2 reanalysis. By the end of the overlapped periods, the monthly mean of the differences between the streams are small, as desired. However, the standard deviations of these differences were shown to be a large fraction (40 to 60%) of the estimated standard deviations of typical analysis errors. It was also shown that the streams do not appear to be converging as it was expected in terms of standard deviations of the differences, since little variation is seen between the beginning and the end of the spin-up period. This occurs although the overlapping streams use the same observations, numerical weather prediction and data assimilation models, and assimilation algorithm, differing only in the background information applied at the beginning of each overlapping period.

How to cite: Carvalho, D., El Akkraoui, A., Errico, R. M., Bosilovich, M., and Privé, N. C.: On the convergence of reanalysis produced by different data assimilation streams: a case study with NASA-GMAO MERRA-2 reanalysis system, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-209, https://doi.org/10.5194/ems2023-209, 2023.

09:45–10:00
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EMS2023-502
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UP3.1
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Onsite presentation
Tímea Kalmár, Rita Pongrácz, and Ildikó Pieczka

Due to its high influence on agriculture, infrastructure, water management, and other areas, precipitation is one of the most important climate factors. Furthermore, climate change is likely to produce more extreme precipitation events and lead to an excess of surface water and floods, which have severe impacts on society. However, it is still one of the major challenges for climate models to realistically reproduce the regional patterns, temporal variability, and precipitation intensity due to the intricate interactions between atmospheric precipitation processes, including cumulus convection, large-scale circulations, planetary boundary layer processes and cloud microphysics. This is especially true for terrains with heterogeneous orography, like the Carpathian region.

For the sake of quantifying the uncertainty and improving the accuracy of the precipitation simulations of the RegCM4.7 regional climate model over the Carpathian region, we evaluate the performance of different physical options at 10 km horizontal resolution, using ERA-Interim reanalysis data as initial and boundary conditions. Altogether 24 simulations were carried out by using various combinations of the physics schemes (2 land surface, 2 microphysics, 3 cumulus and 2 boundary layer schemes) for the year 2010, which was the wettest year in the Carpathian region since the beginning of the regular measurements. Different parameterization combinations lead to different simulated climates, so their variance can serve as an estimate of model uncertainty due to the representation of unresolved phenomena.

The analysis of the RegCM ensemble indicates systematic precipitation biases, which are linked to different physical mechanisms in the summer and winter seasons. Furthermore, problematic interaction between some parameterizations causes large overestimation of the precipitation. Due to the different treatment of moisture in the schemes, there are differences not only between the representations of the precipitation cycle, but also in other climatological variables such as soil moisture, temperature and cloud cover. Based on the results, RegCM4.7 is the most sensitive to the applied convection scheme, but the interactions with the other schemes (e.g., microphysics and land surface) affect not only the total precipitation, but also the convective and stratiform precipitation in some cases.

Acknowledgements. Research leading to this study has been supported by the following sources: the Hungarian National Research, Development and Innovation Fund (under grant K-129162), and the National Multidisciplinary Laboratory for Climate Change (RRF-2.3.1-21-2022-00014).

How to cite: Kalmár, T., Pongrácz, R., and Pieczka, I.: Sensitivity of simulated precipitation to different RegCM configurations over the Carpathian region in the wettest year, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-502, https://doi.org/10.5194/ems2023-502, 2023.

10:00–10:15
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EMS2023-329
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UP3.1
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Onsite presentation
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Joanna Wibig and Joanna Jędruszkiewicz

Heat waves and droughts are two the most frequent weather extremes in Poland, both excerbated by the ongoing global warming. Very often they occur simulateously. The aim of this presentation is identification of cases of simultaneous occurence of these extreme situations, examination of their spatial extent, frequency of occurrence and long-term variability. Reasons of their occurrence are also analysed. On the basis of data from the period 1966-2020 from about 40 stations in Poland reference evaporation indices will be estimated based on Palmer-Monteith formula and together with precipitation records used to the water balance determination. The results obtained so far indicate on strong increasing trend of evapotranspiration and only very small, statistically insignificant, increase of precipitation. This causes a decrease of the water balance, defined as a difference between precipitation and evaporation. In Poland the water balance is positive in the cool part of the year and negative in the growing season. This causes that a water deficit  in the growing season will be more and more stressful, especially since the injection of water from the snow cover before the growing season also significantly decreases. Heat waves will be  distinguished basing on maximum daily air temperature. Their number, duration and intensity also have increased considerably from the middle of the twentieth century. The standardized precipitation-evaporation index (SPEI) by  Vicente-Serrano and snow cover data from the winter preceding the drought will be used to find out reasons of simultaneous appearance of heat waves and drought. Among others factors will be considered: the North Atlantic Oscillation, the Arctic Oscillation, Arctic sea ice cover. The research is supported from the Polish National Science Centre (grant 2019/33/B/ST10/01136)

How to cite: Wibig, J. and Jędruszkiewicz, J.: Are heatwaves and drought more likely to occur simultaneously with warming?, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-329, https://doi.org/10.5194/ems2023-329, 2023.

10:15–10:30
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EMS2023-421
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UP3.1
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Onsite presentation
Adrienn Varga-Balogh, Ádám Leelőssy, László Varga, and Róbert Mészáros

Climate change has various effects in different regions on Earth. The shift of global circulation patterns, most importantly changing cyclone tracks and strengthening blocking episodes have serious influence on the regional climate in the midlatitudes. In this study, a 180-year long historical dataset was used to track the change of the circulation patterns over Europe, since different weather types and precipitation can be associated with different synoptic situations. An automated cyclone/anticyclone detection method was applied on the mean-sea level pressure data from the Twentieth Century Reanalysis Project (NOAA). The European domain was split into the areas of low and high pressure systems, thus in each location we were able to investigate the distribution of cyclonic and anticyclonic effects. Clustering methods were used to study the long-term shift of pressure centers.

In the 1836–2015 period, largely increasing anticyclonic influence can be seen in the Mediterranean, underlining the increasing risk of droughts. In the European domain, anticyclonic clusters generally shifted towards the Mediterranean, while cyclone centers showed a northward shift and a weakening tendency. However, the temporal trend of shifts was not consistent over the long study period with multiple breakpoints over the 20th century. The statistically significant increase of anticyclonic influence over the 180-year long period was between 5–10% for Central Europe and reached 10% in the Mediterranean. Increasing frequency of low-pressure systems was found in Northern Europe. Results coincide with the regional climate impacts reported in literature and highlight the importance of the investigation of changes in climate dynamics over this highly populated area.

How to cite: Varga-Balogh, A., Leelőssy, Á., Varga, L., and Mészáros, R.: Increasing anticyclonic influence over Central Europe between 1836–2015, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-421, https://doi.org/10.5194/ems2023-421, 2023.

Coffee break
Chairpersons: Monika Lakatos, Gudrun Nina Petersen
11:00–11:15
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EMS2023-303
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UP3.1
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Onsite presentation
Tim Hewson

In October 2022 a cyclone that deepened explosively over the South Pacific - the "Peter I Storm" - acquired a central pressure close to 900hPa, which by some margin is lower than has been seen before (in modern times) for a cyclone in either the northern or southern hemisphere extratropical regions. Whilst observation coverage in the area was sparse, the exceptional central pressure value was supported by operational numerical model output from both ECMWF and GFS models, and also by the ERA5 re-analysis. This talk will examine the evolution of the cyclone, that spanned more than 10 days: from its tropical origins near to Tonga to its final decay on the fringes of Antarctica. We pose the question: what might have contributed to the occurrence of such an extreme? Surface characteristics, such as roughness and sea ice coverage, and large-scale dynamics will be referenced. Operational ECMWF ensemble predictions will also be shown; these suggest that the event was remarkably predictable for lead times of 5 days and less. The ECMWF forecasts will also be compared with some modern data-driven AI-based forecasts, to examine if they were as good. 

The extreme event will then be placed in a climatological context, using ERA5, to reference questions about 'trends in extremes', examining also northern hemisphere behaviour, and comparing the cyclone's life-cycle with that of the northern hemisphere "record holder" from 1986. We will also cross-reference another extreme cyclone case from 1941, to further examine the question of re-analysis integrity in the face of sparse data coverage. It seems that the ERA5 representation of cyclones with extreme central pressures is quite robust. This is probably because such cyclones tend to have a large areal extent. The talk will conclude with contrasting remarks about representativeness for smaller cyclones, that can have particular relevance for high impact weather over Europe.

How to cite: Hewson, T.: A Record Breaking Extratropical Cyclone in 2022: A Sign of Climate Change ?, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-303, https://doi.org/10.5194/ems2023-303, 2023.

11:15–11:30
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EMS2023-517
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UP3.1
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Onsite presentation
Mary Curley, Barry Coonan, Ciara Ryan, and Conall E. Ruth

Climatological Standard Normals (CLINO) are the mean or average values of a climate variable over a standard reference period. The World Meteorological Organization (WMO) established that the length of the reference period should be 30 years, with a recommendation to update the climate normals every 10 years, to provide representative reference values for recent climatic conditions. 

Climate normals are used for two principal purposes. They serve as a benchmark against which recent or current observations can be compared, including providing a basis for many anomaly-based climate datasets. They are also widely used as a reference baseline to provide context for future climate projections.

By applying the WMO data requirements and criteria, Met Éireann has compiled a set of climate normals for the period 1991-2020 for a range of parameters including temperature, precipitation, solar radiation, wind and pressure. Annual, seasonal, and monthly normal values for the period 1991-2020 were compiled using quality assured data obtained from Met Éireann’s observation network. Values are averaged for each month over the 30-year period to obtain the long-term average. Where there are gaps in data, estimates are made using data from neighbouring stations. Long-term averages for stations are then used to generate maps and gridded data at a 1km resolution.

A comparison of the most recent 30-year period with the 1961-1990 period shows an increase in annual mean temperature of approximately 0.7°C. All seasons experienced a rise in mean temperatures, with Spring displaying the greatest differences between the two periods.

On an annual basis, averaged over the country, there has been an increase of approximately 7% in rainfall totals between the two normal periods (1961-1990 and 1991-2020), with the greatest increases observed in the western half of the country. All seasons show an overall increase in rainfall but there are regional variations.

Here we present the data and methods used to produce the latest set of climate normals for Ireland as well as an assessment of trends between the two normal periods, 1961-1990 and 1991-2020.

From September 2023, weather and climate statistics will reference the new long-term average period 1991-2020, unless otherwise stated. These will replace the 1981-2010 long-term averages that are currently in use. The historical baseline period of 1961-1990 will be retained for use in climate change assessments.

How to cite: Curley, M., Coonan, B., Ryan, C., and Ruth, C. E.: Ireland’s Climatological Standard Normals (CLINO) 1991-2020, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-517, https://doi.org/10.5194/ems2023-517, 2023.

11:30–11:45
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EMS2023-526
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UP3.1
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Onsite presentation
Benedikt Becsi and Herbert Formayer

Recently, interest in analysing regional climate change impacts in light of global warming levels (GWLs) has risen, not least because the IPCC used them in their current report cycle. GWLs shift the focus point in the uncertainty chain compared to classical scenario approaches like SRES or RCPs, and allow a more comprehensive analysis of the differences and implications of a 1.5°C vs. a 2°C warmer world. Although a lot of research has been done to link GWLs to regional climate change signals within global circulation model (GCM) outputs, or between GCMs and regional climate model (RCM) outputs, there is a lack in studies to link GWLs to localised climate scenarios. In contrast to analysing regional signals within GCMs and between GCMs and RCMs, often no direct link can be established between the global and the downscaled models, especially when they are driven by an older version of GCMs (e.g. CMIP3, CMIP5), because many local climate scenarios have not been updated since the release of CMIP6.

Here, a version-agnostic methodology of linking local climate scenarios to GWLs derived from CMIP6 GCMs is presented for the example of the Austrian climate scenarios (ÖKS15). It is an extension of the time sampling method where time slices around the crossing point of global mean temperature over the respective GWL threshold are derived from GCMs. When using those time slices directly, uncertainties emerging from the local scale would intersperse the anthropogenic warming signal with natural climate variability. To avoid this, instead of explicit time periods, the respective climate change signals are used to select the period of interest from the local scenarios. This approach promises a more robust analysis compared to the time sampling method, because it considers error propagation biases due to the downscaling method and ambiguous reference periods to derive the anomalies.

The study is expected to contribute to locally adapted assessment reports on climate change impacts that intend to use the IPCC methodology, like the second Austrian Assessment Report on Climate Change (AAR2).

How to cite: Becsi, B. and Formayer, H.: Linking global warming levels to local climate scenarios: applicability, prospects and uncertainties, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-526, https://doi.org/10.5194/ems2023-526, 2023.

11:45–12:00
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EMS2023-528
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UP3.1
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Onsite presentation
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László Báder, József Szilágyi, and Klaudia Négyesi

The series of severe droughts in Europe from the beginning of this century may have a root cause to which we do not pay enough attention. The key function of the water cycle - energy, and water distribution - is directly influenced by climate change. Analyzing the trends of ERA5-Land gridded meteorological data for Central-Europe confirms significant trends with p=0.05 for temperature, relative humidity, and net radiation. Average increase of net radiation energy in Hungary is about 80mm in water equivalent during the last four decades. This increased load has an impact on the energy transfer processes where evapotranspiration has the largest share.

Trends of actual evaporation and Penman reference evaporation were analyzed in the study region. Evapotranspiration was estimated by the complementary relationship method of evaporation. Both parameters show significantly increasing trend. The warning signal, however, is that the gap between them is increasing, too. Demand (represented here by reference evaporation) is increasing faster than supply (evapotranspiration). Considering that water is the dominant energy transfer medium of climatic energy, an opening gap can be interpreted as the stability of the energy distribution system is decreasing. This change can trigger a growing risk of droughts, where drought is a symptom of system underperformance.

The common interpretation of evaporation as a loss factor in the hydrological cycle should be urgently changed to a functional view: energy distribution via evaporation is a vital environmental service. Atmospheric circulation and the water cycle are inherently connected. Saving water may not be the correct approach to mitigate climate change, as it only amplifies the deficiencies of the energy exchange process. One cannot stop desertification by chasing water use efficiency and using less water, but the other way around: scarcity of water can only be eliminated by ensuring that a wealth of water resources is available for evapotranspiration, thus for smooth distribution of climatic energy.

How to cite: Báder, L., Szilágyi, J., and Négyesi, K.: Freshwater paradox: will saving of water help in mitigating climate change or increase the instability of the hydrological cycle?, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-528, https://doi.org/10.5194/ems2023-528, 2023.

12:00–12:15
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EMS2023-546
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UP3.1
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Onsite presentation
Andreas Dobler, Rasmus Benestad, Cristian Lussana, Julia Lutz, Oskar Landgren, Jan Erik Haugen, Abdelkader Mezghani, and Kajsa M. Parding

Reanalysis as well as satellite data from TRMM show a decreasing trend in the daily precipitation area between 50°S and 50°N throughout the past decades. The trend is highly correlated to global mean temperatures and indicates the change in the hydrological cycle may be connected to the warming climate, resulting in increased drought frequencies and more intense rainfall. However, changes in the satellite networks provide inhomogeneous data sets and have possibly affected the precipitation area in the satellite and reanalysis dataset. Global climate and Earth system models, although suffering from biases in precipitation amounts and frequencies, are not influenced by changing observation systems. Thus, they provide a possibility to test the hypothesis of a decreasing precipitation area in a warming climate.

Here, we have used simulations from CMIP6 and CMIP5 to test this hypothesis. The models following the high-emission scenarios SSP5-8.5, SSP3-7.0 and RCP8.5 showed a clear decrease in the precipitation area towards the end of the 21st century. Compared to changes in the satellite and reanalysis data, the magnitude in the CMIP models was smaller. The decrease was apparent globally but most pronounced between 50°S and 50°N. Zonal averages of the daily precipitation area showed a general decrease from 5° to 50° on both hemispheres and an increase from 55° towards the poles, indicating a poleward shift of precipitation. In the Arctic region, the daily precipitation area was increasing from 20% to 30% on average.

Along with the precipitation area changes, the precipitation frequency decreased between 5° and 50 °S and increased in the polar regions. In the Northern Hemisphere, the precipitation frequency decreased over the North Atlantic, the Mediterranean region and Middle America. At the same time, precipitation intensity increased mostly everywhere.

Our analysis supports that in a warming climate, the daily precipitation area may indeed shrink, as found in reanalysis and satellite data. The results also showed that an increase in precipitation is coupled with an increase in precipitation intensity, while a decrease in precipitation is coupled with a decrease in frequency. However, the latter was generally coupled with an increase in precipitation intensity, suggesting increased drought frequencies and more intense rainfall at the same time.

How to cite: Dobler, A., Benestad, R., Lussana, C., Lutz, J., Landgren, O., Haugen, J. E., Mezghani, A., and Parding, K. M.: Decrease of the global precipitation area in CMIP6 projections, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-546, https://doi.org/10.5194/ems2023-546, 2023.

12:15–12:30
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EMS2023-193
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UP3.1
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Online presentation
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Matyas Herein, Tamas Tel, and Timea Haszpra

We review recent results of large ensemble climate projections considering them to be simulations of chaotic systems. The quick spread of an initially localized ensemble in the first weeks after initialization is an appearance of the butterfly effect, illustrating the unpredictability of the dynamics. We show that the growth rate of uncertainty (an analogue of the Lyapunov exponent) can be determined right after the initialization. The next phase corresponds to a convergence of the no longer localized ensemble to the time-dependent climate attractor, and requires a much longer time. After convergence takes place, the ensemble faithfully represents the climate dynamics. Concerning a credible simulation, the observed signal should wander within the spread of the converged ensemble all the time, i.e. to behave just as any of the ensemble members. As a manifestation of the chaos-like climate dynamics, one can imagine that beyond the single, observed time-dependent climate, a plethora of parallel climate realizations exist. Converged climate ensembles also define the probability distribution by which the different climate realizations occur. Large ensemble simulations were shown earlier to be credible in the sense formulated. Here in addition, an extended credibility condition is given which requires the ensemble to be a converged ensemble, valid also for low-dimensional models. Interestingly, to the best of our knowledge, no low-order physical or engineering systems subjected to time-dependent forcings are known for which a comparison between simulation and experiment would be available. As illustrative examples, the CESM1-LE (Community Earth System Model Large Ensemble) climate model and a chaotic pendulum are taken.

How to cite: Herein, M., Tel, T., and Haszpra, T.: Where are the coexisting parallel climates? Large ensemble climate projections from the point of view of chaos theory, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-193, https://doi.org/10.5194/ems2023-193, 2023.

Posters: Thu, 7 Sep, 16:00–17:15 | Poster area 'Day room'

Display time: Wed, 6 Sep 10:00–Fri, 8 Sep 13:00
P74
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EMS2023-75
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UP3.1
Tomas Krauskopf and Radan Huth

Trends in temperature variability are often referred to have higher effect on temperature extremes than trends in the mean. We investigate trends in three complementary measures of intraseasonal temperature variability: (a) standard deviation of mean daily temperature (SD), (b) mean absolute value of day to day temperature change (DTD) and (c) 1-day lagged temporal autocorrelation of temperature (LAG). It is a well-established fact that different types of data (station, gridded, reanalyses) possess different temperature characteristics and particularly its trends. Moreover, it has been uncovered during our research that trends in measures of variability are more sensitive to data inhomogeneities. Therefore, we use five different datasets, one station based (ECA&D), one gridded (EOBS) and three reanalyses (JRA-55, NCEP/NCAR, 20CR), and compare them. The period from 1961 to 2014 where all datasets overlap is examined and the linear regression method is utilized to calculate trends of investigated measures in summer and winter. Intraseasonal temperature variability tends to decrease in winter, especially in eastern and northern Europe, where trends below -7% per decade are detected for all measures. Decreases in DTD and LAG (increase in persistence) prevail also in summer while summer SD tends to increase. The increase in the width of temperature distribution and the simultaneous increase in persistence indicate a tendency towards the rise in the frequency of extended extreme events in summer. Our results do not imply that reanalyses are the least accurate in determining trends of temperature variability. JRA-55 appears to be the least diverging from other datasets, while the largest discrepancies were detected for DTD at climate stations. Our consequent research expose that the type of calculation of mean daily temperature is crucial to the resulting value of DTD as T(7+14+21+21)/4 shows warm days warmer and cold days colder than T(0-0)/24. This is the possible explanation of discrepancies in DTD trends as many of ECA&D stations (e.g. German stations at 2001) underwent a change in this calculation during the observed period.

How to cite: Krauskopf, T. and Huth, R.: Trends in intraseasonal temperature variability in Europe: comparison of station data with gridded data and reanalyses, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-75, https://doi.org/10.5194/ems2023-75, 2023.

P75
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EMS2023-91
|
UP3.1
|
Babak Ghazi, Rajmund Przybylak, and Aleksandra Pospieszyńska

Droughts and floods are the most hazardous disasters to affect the landscape and human communities. Climate change is increasing their frequency and intensity all around the world. In this research, we study the impact that climate change in central Poland (Toruń) is having on the frequency of meteorological droughts and risk of floods occurrence in the region, based on the standardised precipitation index (SPI) as one of the most common and effective indices. Although the SPI was developed for monitoring droughts, previous studies have shown that it can also be applied to recognise wet and normal conditions. Therefore, in this study, we attempt to determine the relationship between SPI values and high flood risk. First, by an average mean ensemble of several general circulation models (GCMs), precipitation for a future period (2026–2100) in Toruń was projected under two climate change socio-economic pathway scenarios (SSPs), SSP1-2.6 and SSP5-8.5. Then, based on the projected precipitation for the future period, the SPI values were calculated. The results indicated that, in general, the precipitation in the study area will increase for scenarios SSP1-2.6 and SSP5-8.5.

Estimation of future meteorological drought based on SPI calculation showed that the frequency of the “Extremely dry” (SPI ≤ ˗2.0) and “Severely dry” (˗1.50 ≤ SPI < ˗2.0) categories will decrease under scenarios SSP1-2.6 and SSP5-8.5, while the frequency of the “Moderately dry” category (˗1.0 ≤ SPI < ˗1.50) will increase for scenarios SSP1-2.6 and SSP5-8.5 relative to the historical reference period (1991–2014).

Estimation of flood risk occurrences in the future period based on SPI values showed that the frequency of “Extremely wet” (SPI ≥ 2.0) will increase for SSP1-2.6 and SSP5-8.5, excluding the future periods 2076–2100 in SSP1-2.6 and 2026–2050 for SSP5-8.5. The frequency of “Very wet” (1.50 ≤ SPI < 2.00) will increase for both scenarios. It is also expected that frequencies of other categories including “Moderately wet” (1.00 ≤ SPI < 1.50), and “Near normal” (˗0.99 ≤ SPI <1) will slightly decrease for both scenarios.

To conclude, a decrease in the frequency of “Extremely dry” and “Severely dry” categories and an increase in the frequency of “Extremely wet” and “Very wet” showed that the occurrence of floods is more probable than droughts in the study area in the future period.

The work was supported by the National Science Centre, Poland project No. 2020/37/B/ST10/00710.

How to cite: Ghazi, B., Przybylak, R., and Pospieszyńska, A.: Estimation of droughts and floods occurrences in central Poland under climate change scenarios, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-91, https://doi.org/10.5194/ems2023-91, 2023.

P76
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EMS2023-130
|
UP3.1
Romana Beranová, Radan Huth, and Eva Plavcová

Different types of meteorological data (station, gridded, reanalysed) are known to have different statistical characteristics for higher order moments, extremes and trends. While the analysis of long-term changes in mean values and extremes is often studied, changes in precipitation variability are rather on the fringes of attention. We use data from stations across Europe (ECA&D project), gridded data (E-OBS, Regen), and several reanalyses (NCEP/NCAR, 20CR, ERA5). We examine the long-term changes in precipitation characteristics in different data sources over Europe. We calculate differences between the datasets and attempt to identify causes of these differences and the specific behavior of the datasets. In addition to the analysis of the trend of the seasonal totals and the probability of precipitation, we focus also on the trends of a day-to-day variability of precipitation. We consider wet-to-wet and dry-to-dry transition probabilities as a measure of short-term precipitation variability. Long-term trends of seasonal values of precipitation variables and their statistical significance are calculated by non-parametric methods (Mann-Kendall test, Kendall statistic). The analysis is conducted on a seasonal basis, with emphasis on winter and summer. We find that each of the datasets has its advantages and drawbacks. Trends in the reanalyses deviate considerably from the observed datasets. This is mainly because of the changes in the type and amount of assimilated data over time. The weakness of the gridded datasets is the unstable number of stations entering the interpolation in time. The main disadvantage of the station data is the lack of representativeness of some climate stations.

How to cite: Beranová, R., Huth, R., and Plavcová, E.: Trends in precipitation variability over Europe on different datasets, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-130, https://doi.org/10.5194/ems2023-130, 2023.

P77
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EMS2023-140
|
UP3.1
Martin Mozny, Vojtech Vlach, Lenka Hajkova, Adela Musilova, and Veronika Ouskova

Drought monitoring is based on the analysis of a series of drought indicators. Our analysis was carried out using the Standardized Precipitation Index (SPI) and Standardized Precipitation-Evapotranspiration Index (SPEI) with regard to five different time scales (1, 3, 6, 12, and 24 months). One-month indices better capture short-term moisture conditions, while three- and six-month indices describe medium-term conditions, and twelve- and twenty-four-month indices focus on long-term conditions. Potential evapotranspiration was calculated using the Hargreaves-Samani method. Drought was defined as a sequence of months with negative index values. In addition, spatial and temporal variability, frequency, duration, and intensity of drought in the Czech Republic were analyzed during the study period. Furthermore, the distribution of drought in different elevations was also examined.

Remarkable spatial differences were found in the duration and intensity of drought. Generally, the results of the SPEI index assessment showed longer duration and higher intensity of drought compared to the SPI index assessment. Increasing temperatures cause increased evaporation, particularly in the summer season, leading to an increase in events referred to as flash droughts.

The assessment of drought showed the exceptional nature of the period 2014-2020, which peaked in 2018. This applies to both the duration and intensity of drought. This unprecedented drought had a negative impact on the state of forest stands in the Czech Republic, especially spruce stands, which suffered from water stress and were unable to resist bark beetle calamity. Repeated droughts led to accelerated tree mortality. This contribution highlights the importance of the increasing potential of more frequent and more severe drought events in Central Europe.

 

How to cite: Mozny, M., Vlach, V., Hajkova, L., Musilova, A., and Ouskova, V.: Assessment of drought severity in the Czech Republic from 1961 to 2022, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-140, https://doi.org/10.5194/ems2023-140, 2023.

P78
|
EMS2023-156
|
UP3.1
Valeriy Khokhlov

The past climate change impact on some natural objects is usually studied using available observations or re-analysis data. To assess future climate changes, the only source of information is simulations of global or regional climate models. A particular application depends on the problem to be studied - if the natural object needs to be considered in more detail, then a smaller spatiotemporal grid step in a model must be used. The present study focuses on the methodology for selecting representative simulations from the EURO-CORDEX ensemble by RCP8.5 scenario and assessing near-future temperature and precipitation trends in Odesa, Ukraine.

The approach is to minimize bias in average monthly temperature and precipitation. The 1970–2005 average bias by 76 simulations of the EURO-CORDEX ensemble is about +0.5÷+1.0 °C for the monthly temperature and about –25÷+10 mm for the monthly precipitation sum. The preferably positive bias for precipitation is registered from October to March and a negative one – from April to September with a minimum in July-August. Some models can show almost dry summer, which is not in fact.

The procedure for selecting representative simulations involves choosing the minimum bias in the reference period 1970-2005 and adjusting the results obtained for the scenario simulation period 2006-2020. Minimizing the mean bias allowed the selection of the eight simulations that satisfactorily describe changes in temperature and precipitation over the period 1970-2020. These simulations were then used to assess the near-future climate in Odesa.

The mean temperature in Odesa has increased by ~1 °C over the past 30 years. A significant trend towards an increase in the average annual temperature will continue in 2021-2050, and the temperature will also increase for all months. There exists only little probability of a negative average monthly temperature and only in January. Although the average annual precipitation sum will increase slightly (~ 20 mm), it will decrease significantly in summer and increase in spring and at the end of the year. In general, it seems that the climate of Odesa is moving towards the Mediterranean climate – warm to hot, dry summers and mild, moderately wet winters.

How to cite: Khokhlov, V.: Selection of representative climate simulations to assess near-future climate change in Odesa, Ukraine, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-156, https://doi.org/10.5194/ems2023-156, 2023.

P79
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EMS2023-184
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UP3.1
Seung-On Hwang, Sang-Wook Yeh, and Johan Lee

The relationship between daily mean precipitation and surface air temperature (mean P-T) over the East Asia summer monsoon land region for 1979–2022 and its decadal change are investigated using binned scaling analysis and the Clausius–Clapeyron equation. Mean P-T scaling analysis produces a peak-shaped scaling curve that roughly follows the Clausius–Clapeyron constraint below a threshold temperature at which precipitation reaches its peak and shows negative scaling due to a saturation deficit above the threshold temperature. This feature is similar to the scaling behavior for extreme P-T relationships observed in many previous studies for mid-latitudes, execpt for a different magnitude of precipitation and the C-C scaling rate. It is found that there is distinct regime shift of mean P-T relationship before and after 2000, which is clearly seen in all the parameters such as the threshold temperature, mean precipitation, and scaling rate. The threshold temperature has increased after 2000, indicating that the hydrological response to warming can be explained by C-C scaling prediction at further high temperature. However, the precipitation peak has decreased after 2000, which contradicts well-established increasing and linked tendencies for temperature and precipitation in a warmer world. We therefore conclude that the dependency of daily mean precipitation on daily mean surface temperature may be influenced by hydrological changes in the East Asian monsoon in summer. This poses a concern for the spatio-temporal variability of regional monsoon systems and suggests that localized responses to global warming need to be considered to understand the mean P-T relationship over the East Asia summer monsoon region. 

How to cite: Hwang, S.-O., Yeh, S.-W., and Lee, J.: Change in the relationship between daily mean precipitation and temperature over the East Asia summer monsoon region, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-184, https://doi.org/10.5194/ems2023-184, 2023.

P80
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EMS2023-198
|
UP3.1
Ladislav Markovič and Pavel Faško

Snow cover and its characteristics are among the meteorological indicators that are usually the most affected by the changing climate. In the complex natural conditions of Slovakia, this can mean the emergence of conflicting tendencies even within small regions. In connection with the geographical location of Slovakia, the influence of the greater continentality of the climate of eastern Slovakia, or more pronounced manifestations of the oceanic climate of the western and south-western regions of Slovakia, can also influence formation and durability of the seasonal snow cover (SC). Persistent seasonal snow cover is methodically defined as a period of continuous snow cover that can be interrupted for a maximum of 3 days during the given season. Time series of the daily snow cover depth used in this paper already reached a length of more than a hundred years, which can be a sufficient guarantee of an objective expression of detected changes in the occurrence of persistent seasonal snow cover. In connection with the general decrease of days with the persistent seasonal snow cover, which has not avoided the Central European region, the aim of this paper is to draw attention to the reduction in the occurrence of the persistent seasonal snow cover in Slovakia. It manifests itself in the form of a decrease in the number of days with snow coverat the beginning and at the end of the winter season and its instability during the main part of the season, in which the fluctuation of temperature conditions is accentuated. In the historical context, the shortening of the period with persistent seasonal snow cover in Slovakia began to manifest itself significantly in the second decade of the 21st century.

How to cite: Markovič, L. and Faško, P.: Changes in the occurrence of the persistent seasonal snow cover in Slovakia in the period 1921/1922 - 2022/2023, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-198, https://doi.org/10.5194/ems2023-198, 2023.

P81
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EMS2023-200
|
UP3.1
Lívia Labudová, Kristína Szabóová, and Maroš Turňa

Our contribution is aimed on the investigation of changes in humidity characteristics at the most homogeneously considered stations in Slovakia. We used data on the Penman and the Budyko – Zubenokova´s potential evapotranspiration, Tomlain's irrigation indicator and the SPEI to investigate changes in the moisture characteristics. Tomlain's indicator is calculated as the annual sums of the difference between precipitation and potential evapotranspiration (PET) data. The PET for this indicator was estimated using to the Budyko-Zubenokova´s method. The SPEI is used in operational way for meteorological drought monitoring in Slovakia. The PET considered in the SPEI is estimated according to the Penman-Montheit method, which is also recommended by WMO. To obtain the regions with negative atmospheric evaporative demand, we used the relative SPEI using the coefficients of the theoretical distribution estimated for the spatial averaged data of the PET and precipitation. These coefficients were applied to calculate the SPEI using the station data. The stations were chosen to represent the northern, south-western and eastern parts of Slovakia, as they cover a very diverse orography and they have the longest series of observations. Three reference periods were compared, namely the 1961-1990, 1981-2010 and the most recent reference period, 1991-2020. The main goal of the work was to investigate how the potential evapotranspiration characteristics were changed and to what extent the country has a drying tendency. The comparison of the different reference periods has shown that the annual precipitation sums increased slightly, but their increase does not cover the increase of the PET resulting in the drying tendency. The highest negative change was observed in the south-western and south-eastern part of Slovakia hitting the lowland regions with intensive agricultural land use.

How to cite: Labudová, L., Szabóová, K., and Turňa, M.: Changes in potential evapotranspiration and atmospheric evaporative demand in Slovakia since 1961, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-200, https://doi.org/10.5194/ems2023-200, 2023.

P82
|
EMS2023-249
|
UP3.1
Elena Maines, Alice Crespi, Stefan Steger, and Marc Zebisch

In recent decades, the Alpine regions have been affected by several heavy precipitation events occasionally associated with storms causing landslides, debris flows, forest damage or flooding with cascading impacts to socio-economic systems. There is scientific evidence that a warming climate is likely to induce changes in the intensity and occurrence of precipitation extremes, even though extracting a long-term changing signal on regional and local scale is still challenging and requires an adequate observation coverage.

Some studies on extreme precipitation observed in the Alpine region exist, but only a few focus more in detail on the Trentino-Alto Adige area (north-eastern Italian Alps). In this context, the intensity and frequency of heavy precipitation, their spatial variability and trends over 1956-2020 are analysed for the region based on an archive of quality-checked daily historical records from more than 60 rain gauges.

The annual and seasonal analyses of maxima and exceedances of the 97th percentile show distinctive spatial patterns in both magnitude and seasonality. Maxima primarily occur during summer in the northern and more alpine part of the region, and during autumn in the south where the influence of the Mediterranean climate is more pronounced. Almost two thirds of the analysed stations reveal an increasing tendency in either the intensity or the frequency of heavy precipitation, especially in the north, even though trends are statistically significant only for a limited number of stations (e.g. less than 10% for annual maxima). The 1956-2020 intense precipitation observations are also scaled with global and regional temperatures and results are compared with previous studies in surrounding countries in order to assess global and regional warming effects on extreme changes. Finally, the extreme value distributions based on the 65-year records and two subsequent subperiods (1961-1990 and 1991-2020) provide a first evaluation of changes in statistical properties and precipitation amounts associated to different return periods. This is also used to characterize the local precipitation intensities during the exceptional event which hit north-eastern Alps in 2018, named storm Vaia, with intense precipitation together with extreme wind speed conditions.

This contribution shows and discusses the main results and provides an outlook towards the assessment of climate drivers of precipitation events in the region, the occurrence of compound extremes and links to subsequent impacts.

The research leading to these results has received funding from Interreg Alpine Space Program 2021-27 under the project number ASP0100101, “How to adapt to changing weather eXtremes and associated compound and cascading RISKs in the context of Climate Change” (X-RISK-CC).

 

How to cite: Maines, E., Crespi, A., Steger, S., and Zebisch, M.: Assessment of variability and trends of heavy precipitation in Trentino – South Tyrol (north-eastern Italian Alps) based on rain-gauge records (1956-2020), EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-249, https://doi.org/10.5194/ems2023-249, 2023.

P83
|
EMS2023-266
|
UP3.1
A Study of the Impact of Climate Change on Hydrological Drought Conditions across the World using CORDEX-CORE Simulations
(withdrawn)
Matilde García-Valdecasas Ojeda, Erika Coppola, Fabio Di Sante, Luiza Vargas-Heinz, and Sonia R. GÁmiz-Fortis
P84
|
EMS2023-272
|
UP3.1
Boran Yıldız, Nazlı Doğan, Esma Demirtaş, Abdurrahman Durmaz, and Ahmet Öztopal

Türkiye Üzerindeki Troposferin 3 Ana Basınç Seviyesindeki Aşırı Sıcaklıkların Trend Analizi

Boran Yıldız1, Nazlı Doğan2, Esma Nur Demirtaş3, Abdurrahman Durmaz4, Ahmet Öztopal5

İstanbul Teknik Üniversitesi, Meteoroloji Mühendisliği Bölümü, 34469 Sarıyer İstanbul, Türkiye

yildizb20@itu.edu.tr1, doganna19@itu.edu.tr2, demirtase19@itu.edu.tr3, durmazab17@itu.du.tr4, oztopal@itu.edu.tr5

 

Sanayi Devrimi ile birlikte, kontrolsüzce atmosfere salınan sera gazları neticesinde bugün gelinen noktada, atmosferin küresel olarak ortalama sıcaklığının 1⁰C’nin üstüne çıkmasıyla beraber, karşı karşıya kaldığımız küresel iklim değişikliği sürecinden en az şekilde etkilenilmesi ve iklim değişikliğine uyum sağlanılması noktalarında başlangıç adımı meteorolojik bilgiden geçmektedir. Türkiye konumu itibariyle küresel ısınmanın etkilerinden en fazla oranda etkilenecek ülkeler arasında yer almaktadır. Bu çalışmada Türkiye’nin 6 radiosonde istasyonuna ait 1960-2020 dönemindeki 850 mb, 700 mb ve 500 mb basınç seviyelerindeki aşırı sıcaklıkların trend analizi gerçekleştirilecektir. Çalışmada yöntem olarak Yenilikçi Trend Analizi kullanılarak troposferin 3 ana basınç seviyesinde küresel iklim değişikliğinin etkileri ortaya konulacaktır.

Anahtar kelimeler: İklim değişikliği, sıcaklık, trend analizi, troposfer, Türkiye, YTA.

 

Trend Analysis of Extrem Temperatures at 3 Main Pressure Levels of the Troposphere over Turkey

Esma Nur Demirtaş1, Boran Yıldız2, Nazlı Doğan3, Abdurrahman Durmaz4, Ahmet Öztopal5

İstanbul Technical University, Department of Meteorological Engineering, 34469 Sarıyer İstanbul, Türkiye

demirtase19@itu.edu.tr1, yildizb20@itu.edu.tr2, doganna19@itu.edu.tr3, durmazab17@itu.du.tr4, oztopal@itu.edu.tr5

 

At the point reached today as a result of the uncontrolled greenhouse gases released into the atmosphere with the Industrial Revolution, with the global average temperature of the atmosphere rising above 1⁰C, the first step passes from meteorological information in terms of being least affected by the global climate change process, we are facing, and adapting to climate change. Due to its location, Türkiye is among the countries that will be most affected by the effects of global warming. In this study, trend analysis of extreme temperatures at 850 mb, 700 mb and 500 mb pressure levels in the 1960-2020 period of Turkey's 6 radiosonde stations will be performed. The effects of global climate change will be revealed at the 3 main pressure levels of the troposphere by using Innovative Trend Analysis (ITA) as a method.

Keywords: Climate change, ITA, temperature, trend analysis, troposphere, Türkiye.

How to cite: Yıldız, B., Doğan, N., Demirtaş, E., Durmaz, A., and Öztopal, A.: Trend Analysis of Extrem Temperatures at 3 Main Pressure Levels of the Troposphere over Turkey, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-272, https://doi.org/10.5194/ems2023-272, 2023.

P85
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EMS2023-278
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UP3.1
Csilla Simon, Csaba Zsolt Torma, and Anna Kis

Climate change is one of the greatest challenges we face today. Beside higher temperature values, an increase in the frequency and intensity of extreme weather events are likely to occur in the future, which is also highlighted by the latest IPCC report. Global and regional climate models (GCMs and RCMs, respectively) have become indispensable tools for climate research, but these model simulations are encumbered with uncertainty from a variety of sources. These uncertainties can be quantified and reduced by evaluating several RCMs together, as members of an ensemble, or by applying bias-adjusted results. In our research we focus on the signal of changes in climate extremes related to temperature and precipitation over Hungary based on raw and bias-adjusted data. An ongoing international initiative called CORDEX (COordinated Regional Downscaling Experiments) provides a large number of RCM simulations for 14 domains of the world. EURO-CORDEX is a sub-programme of CORDEX, covering the European domain and providing regional climate projections at a horizontal resolutions of 0.11° (about 12.5 km) and 0.44° (about 50 km). In our study 5 high-resolution RCMs (CCLM, HIRHAM, RACMO, RCA, REMO) are investigated from the framework of EURO-CORDEX. The simulations follow the radiative forcing scenario RCP8.5 and cover the period 1976–2099. The most important step of the research is the bias-correction of the raw RCM simulations by using the most accurate, measurement-based, high-resolution, homogenized and quality controlled HUCLIM dataset currently available for Hungary, which has not been used yet to produce an available bias-corrected database. The internationally accepted percentile-based quantile mapping method was chosen for the bias-adjustment and was performed on a monthly basis. As part of the study, the evaluation of the new database is presented here for two variables (daily precipitation and daily mean temperature).

How to cite: Simon, C., Torma, C. Z., and Kis, A.: A new bias-corrected EURO-CORDEX dataset for Hungary based on the HuClim database, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-278, https://doi.org/10.5194/ems2023-278, 2023.

P86
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EMS2023-289
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UP3.1
Matilde García-Valdecasas Ojeda, Juan José Rosa-Cánovas, David Donaire-Montaño, Emilio Romero-Jiménez, Yolanda Castro-Díez, María Jesús Esteban Parra, and Sonia R. Gámiz-Fortis

Drought is one of the most devastating natural hazards, affecting ecosystems, communities, and their economies worldwide. According to the last IPCC report, is expected, indeed, an increase in severity and frequency of drought under a changing climate, at least over Mediterranean regions. However, is still more uncertain the effect of climate change in other regions in the world.

To analyze the effect of this extreme phenomenon, many drought indices have been developed in recent years based on different hydroclimatic variables and depending on the type of drought under study. Among these indices it is worth mentioning, for meteorological droughts, the Standardized Precipitation Index (SPI) or the Standardized Precipitation Evapotranspiration Index (SPEI), agricultural drought indices such as the Standardized Soil moisture Index (SSI), or those that make use of different variables or multivariate indices such as the Multivariate Standardized Drought Index (MSDI) that combines soil moisture and precipitation, and the Standardized Precipitation Evapotranspiration Soil Moisture Index (SPESMI), an adaptation of the MSDI that incorporates the effect of potential evapotranspiration on the water balance.

This work aims to analyze from meteorological to agricultural droughts projections over Europe using standardized drought indices. For this, we evaluate drought characteristics (i.e., duration and intensity of drought events) for the different drought indicator at scales from 1 to 48 months using an ensemble of climate change regional projections from EURO-CORDEX under a business-as-usual climate change scenario. Changes for the future were analyzed for global warming corresponding to 1.5º, 2º, 3º and 4ºC of temperature above pre-industrial levels. The results of this analysis could offer useful information for adaptation strategies to climate change.

Keywords: standardized drought indices, agricultural droughts, Europe, climate change. projections.

Acknowledgments: This research was financed by the project P20_00035 funded by FEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades, the project “Thematic Center on Mountain Ecosystem & Remote sensing, Deep learning-AIe-Services University of Granada-SierraNevada”(LifeWatch-2019-10-UGR-01), which has been co-funded by the Ministry of Science and Innovation through the FEDER funds from the Spanish Pluriregional Operational Program2014-2020 (POPE), LifeWatch-ERIC action line, and by the project PID2021-126401OB-I00 funded by MCIN/AEI/ 10.13039/501100011033/FEDER Una manera de hacer Europa.

How to cite: García-Valdecasas Ojeda, M., Rosa-Cánovas, J. J., Donaire-Montaño, D., Romero-Jiménez, E., Castro-Díez, Y., Esteban Parra, M. J., and Gámiz-Fortis, S. R.: Climate Change Projections of Agricultural Droughts in Europe: A Comparison between Standardized Drought Indices, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-289, https://doi.org/10.5194/ems2023-289, 2023.

P87
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EMS2023-658
|
UP3.1
Martin Dubrovsky, Radan Huth, Petr Štěpánek, Ondřej Lhotka, Jiří Mikšovský, Jan Meinter, and Tomáš Krauskopf

While much effort has been devoted to analyzing long-term changes of temperature and precipitation in mean values and extremes, studies on changes in variability have been rather scarce. Trends in variability are, however, important, among others because their interaction with trends in mean values determines the degree with which extremes would change. The knowledge of long-term changes in temporal variability is essential for assessments of climate change impacts on various sectors, including hydrology (floods and droughts), agriculture, health, and energy demand and production.

SPAGETTA is a stochastic spatial daily weather generator (WG), which uses first-order multivariate (dimension = the product of the number of variables and the number of gridpoints) autoregressive model to represent the spatial and temporal variability of surface weather variables (including precipitation and temperature). The generator is a suitable tool for assessing changes in the spatial and temporal variability of the weather series because of following reasons: (A) The inter-gridpoint lag-0 and lag-1(day) correlations of both precipitation and temperature included in a set of WG parameters are good representatives for spatial and temporal variability of the two weather variables. (B) Statistical significance of changes in the lag-0 and lag-1 correlations derived from the calibration series may be easily assessed by comparing the changes with a variability (related to the stochasticity of WG) of the lag-0 and lag-1 correlations across multiple realizations of synthetic weather series. (C) Separate effects of changes in various WG parameters (derived, e.g., from RCM-simulated daily series representing the future climate) on any climatic characteristic may be easily assessed by modifying only selected WG parameter(s).

In the first part of the contribution, we employ SPAGETTA generator to analyze recent and future changes in spatiotemporal variability of precipitation and temperature in 8 European regions; these regions are defined in Dubrovsky et al 2020 (Theor. Appl. Climatol.). The recent changes are derived from gridded observational E-OBS time series, and the future changes (2070-2099 vs 1971-2000) are based on multiple RCM-simulated surface weather series. In the second part, we assess separate effects of changes in the means, variability and lag-0 & lag-1 correlations of temperature and precipitation. The changes in WG parameters are derived from a set of 19 RCM simulations, the changes are used to modify corresponding WG parameters calibrated from the E-OBS data, the synthetic series are generated, and the impacts on a set of compound temperature-precipitation characteristics representing “Days” with spatially significant extent of significantly non-normal weather (e.g. hot-dry spells), and the “Spells” of such days, are analyzed.

How to cite: Dubrovsky, M., Huth, R., Štěpánek, P., Lhotka, O., Mikšovský, J., Meinter, J., and Krauskopf, T.: Recent and Future Changes in Spatiotemporal Variability of Precipitation and Temperature and the Impacts on Selected Precipitation-Temperature Indices, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-658, https://doi.org/10.5194/ems2023-658, 2023.

P88
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EMS2023-469
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UP3.1
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Natália Machado Crespo, Natália Pillar da Silva, Ricardo de Camargo, and Rosmeri Porfírio da Rocha

Monitoring near-surface winds near coastal areas is really important since it affects not only the population living nearby but also the energetic sector, such as oil and wind power industries. As an effort to understand the future wind trends in a changing climate, this study presents results from the project Western South Atlantic Climate Experiment for the middle of the century (2031 to 2060); here, future projections of near-surface winds and their extremes over the western South Atlantic are evaluated from regional dynamic downscaling by using two distinct models (WRF and RegCM4) forced by two global climate models (HadGEM2-ES and MPI-ESM-MR) under the worse RCP8.5 warming scenario. In general, the trends show a slight decrease of 0.1 to 0.3 m/s in the mean wind speed for both models over the southwestern South Atlantic adjacent to the continent (between 25º and 35ºS in RegCM4 and 15º and 25ºS in WRF). For the extremes the decrease is amplified, reaching 0.5 m/s; the only exception occurs for WRF forced by HadGEM2, in which there is no trend signal southern 25ºS. For the present climate, WRF and RegCM4 have opposite wind speed biases over the South Atlantic, which propagates to the ocean waves simulation, especially for the extremes. Therefore, in order to reduce the bias propagation, an adjustment of the upper-quantiles of the wind speed (i.e. the extremes) was applied to the present climate simulated winds, which showed an improvement for intense wind speeds. After bias corrections, the future trends of wind speed are also explored.

How to cite: Machado Crespo, N., Pillar da Silva, N., de Camargo, R., and Porfírio da Rocha, R.: Future trends of near-surface winds over the southwestern South Atlantic in two regional climate models, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-469, https://doi.org/10.5194/ems2023-469, 2023.

P89
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EMS2023-487
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UP3.1
cheng shen

Understanding the future changes in global terrestrial near-surface wind speed (NSWS) at specific global warming levels (GWLs) is essential for climate change adaptation. Previous studies have projected NSWS changes, but the changes with different GWLs have yet to be studied. In this paper, we use the Max Planck Institute Earth System Model large ensembles to evaluate the contributions of different GWLs to NSWS changes.

Our results show that NSWS decreases over the Northern Hemisphere (NH) mid-to-high latitudes and increases over the Southern Hemisphere (SH) as GWL increases by 1.5◦C–4.0◦C relative to the preindustrial period, and that these characteristics are more significant with stronger GWLs. The probability density of NSWS shifts toward weak winds over NH and strong winds over SH between the current climate and the 4.0◦C GWL. Compared to the 1.5◦C GWL, NSWS decreases −0.066m s−1 over NH and increases +0.065m s−1 over SH with 4.0◦C GWL, with the decrease and increase being most significant in East Asia and South America, reaching −0.21 and +0.093m s−1, respectively.

The changes in temperature gradient induced by global warming could be the primary factor causing the interhemispheric asymmetry of future NSWS changes. Intensified global warming induces the reduction of Hadley, Ferrell, and Polar cells over NH, and the strengthening of the Hadley cell over SH could be another determinant of asymmetry changes in NSWS between two hemispheres.

Our study highlights the importance of considering different GWLs when projecting future NSWS changes. It also provides valuable insights into how the changes in temperature gradient and atmospheric circulation induced by global warming affect NSWS changes differently in the two hemispheres, which has important implications for climate change adaptation and mitigation strategies. The results of this study will contribute to a better understanding of the impacts of global warming on wind resources and wind energy production.

How to cite: shen, C.: Projected near-surface wind speed based on CMIP6 GCMs, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-487, https://doi.org/10.5194/ems2023-487, 2023.

P90
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EMS2023-512
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UP3.1
Analysis of surface air temperature and precipitation trends and climate indices in mountain areas in Spain
(withdrawn)
Ramón Viloria and Verónica Tricio
P91
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EMS2023-541
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UP3.1
Agnieszka Wypych

Water vapour content in the troposphere, regarding its close and complex relationship with air temperature, plays a crucial role in numerous processes in the ocean-atmosphere system. Contemporary global warming forces an increase in the water vapor absorption capacity by about 6-7% per 1K therefore in areas where a constant supply of water vapor is possible (oceans) simultaneously with the temperature growth, evaporation processes intensify and the specific humidity of the air increases. Over the land, especially with the continental nature of the climate, where evaporation possibilities are limited and atmospheric circulation is the main moisture source, a reduction in relative humidity and an increase in humidity deficit and increasing drought risk as a consequence has been observed. 

The aim of the study is to estimate the intensity of meteorological drought in Central Europe under present and future climate conditions resulting from increasing available water capacity of the troposphere.  

Variability of tropospheric moisture content up to 700 hPa pressure level will be examined, including its various characteristics in the period 1961-2022 and its future projections to 2100 using ERA5 and EUROCORDEX RCP 4.5 and RCP 8.5 scenarios data respectively. 

Drought risk will be assessed using moisture deficit information as well as its impact on particular drought indices. 

The preliminary results clearly confirm the increasing risk of moisture deficit in 21st century caused by increasing water vapor absorption capacity resulting from the temperature growth and no extra moisture sources in Central Europe.  

How to cite: Wypych, A.: Tropospheric moisture content variability as a factor of drought intensity in Central Europe , EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-541, https://doi.org/10.5194/ems2023-541, 2023.