In the Mediterranean region, a wide variety of cyclogenesis mechanisms are known to develop, including baroclinic waves from the Atlantic, baroclinic wave cut-off and Warm Seclusions. These mechanisms have been shown sometimes to produce Tropical-Like Cyclones (TLC), Intense Mediterranean Cyclones (IMC) and Explosive-Cyclogenesis (EC). Depending on the cyclone's class, the characteristic frequency of appearance can vary, ranging from tens per month to around 1-1.5 per year, as in the TLC case. ECs are among the rarest and probably the most intense and destructive cyclone events that can develop; they usually originate at high latitudes during wintertime, mainly over the sea, preferring areas with relatively  strong Sea Surface Temperature (SST) gradients. These events are characterized by a relatively fast drop of pressure at the centre of the cyclone, approximately more than 1hPa/hr in a time window of  24hr, or 12 in other milestone works. Several recent studies investigated the formation of ECs over the Mediterranean Basin (MB). EC formation is an extremely complex process, mostly driven in the MB by dry air intrusions from the stratosphere and by Atmospheric Rivers. Here, by using ERA5 reanalysis dataset, we first conducted a physical and dynamic analysis of the most intense cyclone events that occurred in the Mediterranean basin in the period 1979-2020, identifying factors that triggered and contributed to the intensification of such events. According to Sanders’ and Gyakum’s definition of Bergeron–a parameter that describes ECs’ deepening rate and varies from 28mb/(24h) at the pole to 12 mb/(24h) at latitude 25°N–, and its mid-latitude 12 hours adaptation introduced by Zhang, we were able to classify them in the three aforementioned categories. Moreover, by using EOFs, we outlined synoptic configurations that are more likely to drive the phenomena, highlighting the role of the SCAND index and NAO-. We further investigated the deepening with a new promising approach involving the use of 6-hour timespans in order to single out all those systems with the strongest pressure gradients and quickest evolution, highlighting the differences between cyclones developing on the sea and others undergoing evolution related to semidiurnal atmospherical tides in northern Africa. Further analysis is being undertaken to determine the cyclones’ phases and their main morphological characteristics, as well as their correlation with atmospheric rivers and SST anomalies in the Central Mediterranean Basin.

How to cite: Carniel, C. E., Ferretti, R., Ricchi, A., Curci, G., Miglietta, M. M., Reale, M., Serafini, P., Wellmeyer, E. D., and Zardi, D.: Detection, classification and physical analysis of Explosive Cyclones in the Mediterranean Region: a full exploitation of ERA5 dataset, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-17, https://doi.org/10.5194/ems2023-17, 2023.

Snowfall is an important component of the winter climate in Romania, influencing various economic sectors such as transportation, agriculture, and tourism. Previous studies have identified several synoptic patterns that can bring snow in south-eastern Europe, including Mediterranean Cyclones (MCs). However, the contribution of these cyclones to snowfall in Romania has not been thoroughly investigated.

This study aims to quantify the contribution of MCs to snowfall in Romania. Daily snowfall data from ERA5-LAND covering the period 1981-2020 were analyzed, along with the corresponding atmospheric circulation patterns. The MCs trajectory is based on the “best tracks” produced by the 3T initiative of the COST Action, comprising tracks for the 1979-2020 period. This method is based on 10 different cyclone tracks, using an hourly ERA-5 reanalysis data set, at a 0.25 spatial resolution. These 10 tracking methods are combined to obtain a composite track.

The results indicate that, on average, more than 60% of total snowfall in eastern and southern Romania is due to MCs manifestation. Moreover, in some particular years, in most parts of southern Romania, 90% of snow events are due to the Mediterranean cyclones. In the northern and western parts of Romania, the fraction of snowfall due to the MCs is less than 20%. This can be explained by the fact that here the westerly atmospheric circulation can heavily contribute to the total snowfall amount.  The snowfall amount related to the MC varies between 40 and 290 mm. The lowest values are within the plain areas from the west, south, and east of Romania, instead, the highest values are within the mountains, varying between 40 and 290 mm.

The findings suggest that Mediterranean cyclones are an important factor in the climate of Romania, and their contribution to snowfall should be taken into account in forecasting and planning socio-economic activities.

Acknowledgment 

This work was co-funded by the European Social Fund, through Operational Programme Human Capital 2014-2020, project number POCU/993/6/13/153322, project title "Educational and training support for PhD students and young researchers in preparation for insertion into the labor market".

How to cite: Amihăesei, V.-A., Raveh-Rubin, S., Sfîcă, L., Cheval, S., and Dumitrescu, A.: Contribution of Mediterranean Cyclones to the snowfall accumulation over Romania, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-356, https://doi.org/10.5194/ems2023-356, 2023.

An important source of floods in Central Europe are so-called Vb cyclones (i.e., cyclones that move across the Mediterranean Sea and then move northward toward Central Europe along the eastern flank of the European Alps). Embedded convective precipitation contributes to flood risk through Vb precipitation events. This contribution depends on temperature and additional variables.

This study presents km-scale, i.e. convection-permitting, simulations with limited-area model COSMO-CLM using the MedCORDEX domain and quantification of the convective precipitation contribution during a set of extreme Vb events using a Lagrangian method for tracking convective cells [1]. In addition, this set of km-scale Vb event simulations is used to train a diagnostic of the convective fraction (based on simulated vertical velocity and vorticity in the mid-troposphere) following Poujol et al. [2]. This diagnostic method, applied to a coupled MedCORDEX COSMO-CLM/NEMO regional climate simulation with an atmospheric grid spacing of about 12 km, allows us to investigate and quantify the change in the convective fraction of Vb precipitation in an SSP5-8.5 climate scenario. In this simulation, the mean Vb precipitation decreases over the course of the century, but the convective fraction, and thus the flood risk associated with locally intense precipitation, increases.

[1] Purr. C., E. Brisson, and B. Ahrens, Convective rain cell characteristics and scaling in climate projections for Germany, Int. J. of Climatology, 41, 3174-3185 (2021).

[2] Poujol, B., S. Sobolowski, P.A. Mooney, S. Berthou, A physically based precipitation separation algorithm for convection‐permitting models over complex topography, Quarterly Journal of the Royal Meteorological Society, 146, 748-761 (2019).

How to cite: Ahrens, B. and Hamouda, M.: On convective enhancement of Vb-events in present and warmer climate, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-151, https://doi.org/10.5194/ems2023-151, 2023.

A multitude of factors influence the size and intensity of a wildfire and the extensive damage it will cause. Among these are the landscape features, soil moisture and type and amount of vegetation. Atmospheric conditions such as heat waves, ‘correct’ wind speed, wind direction and changes in the wind direction, as well as atmospheric instability are key factors in the spread of the wildfire.

Dry Intrusions are slantwise descending airstreams that descend over 400hPa in 48 hours. They form as part of mid-latitude cyclones bringing to the surface dry upper tropospheric air and may bring to the surface either a cold or warm temperature anomaly. Dry Intrusions are known to destabilize the lower troposphere, lead to stronger winds at the surface and have been found to strengthen the cold front in cases of extreme wildfires in Australia.

In this work we globally analyze the co-occurrence of large wildfires and Dry Intrusions, using a Global Fire Atlas (GFED, Andela et al., 2019) and a calculated Dry Intrusion trajectory database based on ERA5 reanalysis (Hersbach et al., 2020). We find that in fire prone areas of the world there is a strong connection between the most extreme wildfires and the occurrence of Dry Intrusions. We examine this relation in different regions in Europe, Asia, America and Australia, areas in which the frequency of Dry Intrusions vary, and show that the connection is season dependent. Identifying processes that influence the spread of wildfires can improve their current forecast and future predictions in a changing climate.

How to cite: Magaritz Ronen, L. and Raveh-Rubin, S.: Dry Intrusions and Their Role in Extreme Wildfires, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-286, https://doi.org/10.5194/ems2023-286, 2023.

Intense heatwave periods increase the likelihood of extreme wildfires which can lead to negative impacts on many socio-economic sectors. Also, there is still a need to better understand how this phenomenon can impact specific regions in terms of fire danger. The present study aims to investigate three heatwave periods occurring in 2003, 2018 and 2019. All the periods were associated with significant wildfires, two of them linked to mega fires in southern Portugal. The MesoNH is a full-physics non-hydrostatic limited-area research model able to represent atmospheric motions in different scales and has been used to explore the structure and dynamics of the atmosphere during the events. The model was configured with 2.5 km grid spacing and performed for several days depending on the episode. All the experiments were designed with 50 vertical sigma levels unequally spaced, stretching gradually from 30 m (bottom) to 900 m (top). Initial and lateral boundary conditions were provided by European Centre for Medium-Range Weather Forecasts (ECMWF) analysis, with updates every 6 h. The Monchique wildfires in August 2003 and 2018 burned above 25,000 ha. In 2019, the Vila de Rei wildfire burned almost 10,000 ha. All these wildfires’ events occurred under a heatwave influence. The numerical experiment allowed identifying some areas with potential to be affected by wildfires, mainly the regions where orographic effects act to enhance the fire danger. The atmospheric conditions simulated helped to explain the intense fire activity for several days. The heatwave environment associated with extreme heat, very low humidity, and airflow interacting with the local topography favoured the behaviour and evolution of the fires. In this study, the findings show the benefits of the use of cloud-resolving models over large domains to assess the fire danger conditions and helped us to better understand the atmospheric dynamic influencing the development of wildfires. Furthermore, the results may help define firefighting strategies in specific areas, namely in Southern Portugal. This study was funded by national funds through FCT-Foundation for Science and Technology, I.P. under the PyroC.pt project (Ref. PCIF/MPG/0175/2019).

How to cite: Purificação, C., Campos, C., Henkes, A., and Couto, F. T.: Use of atmospheric modelling to assess fire danger in mainland Portugal during heatwave periods, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-302, https://doi.org/10.5194/ems2023-302, 2023.

Very high-resolution (sub-kilometric) simulations are becoming more and more frequent thanks to the increase of modelling knowledge and computational resources. Due to this fast progress, it then becomes essential to verify these simulations in the representation of high-impact convective weather. In this work, we evaluate this kind of simulations (500 m. of resolution) on two specific problems which are highly sensible to increasing resolution: A very high-impact static convective storm formed in front of Valencia (Spain) and a tropical-like cyclone (Medicane Ianos) over the Ionian Sea.

The storm in Valencia produced heavy precipitation and reported the largest accumulation for one day in May for Valencia. The socioeconomic impact was also severe. This event had very low predictability in high-resolution convection-allowing models. The associated environment was not especially favourable to support convective activity, but the formation of low-level wind convergence may organize convective systems. Therefore, this storm is a challenge from a numerical modelling point of view. None of the national operational models over the region showed signals of convective activity with such features in the east of Spain. However, initial simulations at 500 m of resolution seems to be able to simulate the system.

Ianos was a rare Mediterranean tropical-like cyclone, behaving as a hurricane, that impacted the eastern Mediterranean on 17 and 18 September 2020, especially Greece, leaving severe damage. Operational forecasts of this event were not highly valuable, thus is it a highly recommended case study.

We evaluate these simulations, with special focus on the representation of convective activity and mesoscale dynamics, from an operational numerical weather prediction model in their research mode, the HARMONIE-AROME model. HARMONIE-AROME is a convection-permitting model which belongs to ACCORD modelling community, and it’s used operationally in some European countries. Also, this model is being used in European projects such as Destin-E Extremes and UWC. Thus, it becomes necessary to evaluate this model’s behavior for very high-impact convective event forecasting, given also their expected worse impact with anthropogenic climate change.

How to cite: González-Alemán, J. J., Calvo, J., Martín, D., Viana, S., Calvo-Sancho, C., and Morales, G.: Evaluating sub-kilometric simulations for high-impact convective activity with the HARMONIE-AROME model, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-155, https://doi.org/10.5194/ems2023-155, 2023.

A crucial step in developing a strategy against natural hazards is the analysis of weather extremes in the past. Due to the multiplication of their impacts when occurring in a larger area, we strongly recommend not evaluating the extremes only at individual sites but assessing regional extreme weather events. The presented Czech Extreme Weather Database (CZEXWED) comprises six types of extreme events, namely, heat waves, cold waves, air temperature drops, windstorms, heavy precipitation events, and heavy snowfalls. To date, it covers the period 1961–2020. To minimize methodological differences in the process of evaluating various types of extreme weather events including compound events, we employed the weather extremity index (WEI), a universal indicator based on the evaluation of return periods of relevant variables. Each event is characterized not only by the WEI value but also by its spatial extent and duration.

Heat and cold waves in Czechia generally reach higher WEI values than other types of extreme weather because they usually affect larger areas. The number and extremity of heat waves are increasing significantly, while the opposite may be true for cold waves and windstorms. Air temperature drops defined by declines in daily maximum air temperature are frequent in the warm half-year, but three of four top events occurred in January. Windstorms and heavy precipitation events prevailed in the cold and warm half-years, respectively, but weaker events of these types also occurred during the opposite season. A comparison of CZEXWED with event lists from the wider Central European region shows that Czech and Central European extreme events correspond well with each other.

How to cite: Müller, M. and Kašpar, M.: CZEXWED: the unified Czech Extreme Weather Database, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-589, https://doi.org/10.5194/ems2023-589, 2023.

Cyclones are known as one of the biggest hazards to life and property. They can lead to a number of different hazards such as storm surges, floods, very high wind speeds, tornadoes and lighting. The combination of these hazards greatly increases the potential for loss of life and damage of properties. California experienced a devastating and deadly "bomb cyclone" on March 21st (2023), causing widespread destruction and claiming at least five lives. Many people remained without electricity until Thursday morning (March 23rd). Whereas it is hard for models to predict the formation and trajectory of bomb cyclones, Jua’s model, Vilhelm, predicted the formation of the cyclone about 40 hours before it hits California. In addition, it was offering a high level of accuracy in predicting the storm's trajectory 24 hours in advance. Furthermore, Vilhelm's predictions regarding the start of cyclone's dissipation on 22nd March proved to be accurate.

During our analysis on the cyclone, we selected wind speed and pressure as suitable indicators to forecast the formation and trajectory of the cyclone. At 00:00 on March 20th, Vilhelm forecast wind speeds at the 850 hPa and 1000 hPa pressure levels that correctly identified the formation, extension and movement of the cyclone that would hit California on March 21st. In addition, the mean sea level pressure forecasts of the Vilhelm model on 20th March (00:00) approved these findings at the atmospheric layers and therefore the physical consistency of the AI based system. 

Given that the Vilhelm model offered an accurate forecast for the formation, extension, dissipation and crucially, the trajectory of the cyclone, there is a strong potential for it to be used as a global “Atmospheric Hazards Warning System”.

How to cite: Gabler, M. V., Wuillaud, J., Taheri Shahraiyni, H., Neupert, D., Grigoryev, A., Almeida, R., Galimzhanov, A., Hernandez, G. M., Daubinet, J. D., Ekhtiari, N., Song, R. J., Dudbridge, P., and Tarakci, E.: Vilhelm: A Novel AI-based Global Weather Forecasting System for the Prediction of Atmospheric Hazards, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-357, https://doi.org/10.5194/ems2023-357, 2023.

It is well known that atmospheric environments across Australia, Europe and the United States are conducive to the occurrence of convective storms resulting in significant tornadoes, giant hail and damaging winds. However, while many studies have focused on evaluating convective environments over specific regions, only a limited number of elaborations compared different parts of the world. Therefore, in this work we use severe weather reports, ground lightning detection data and ERA5 reanalysis over the last 20 years to address the following research question: do severe storms across Australia, Europe and the United States share environmental similarities? A comparison of composite vertical profiles of temperature, moisture and wind highlighted several consistent features that are common for specific hazards among all three continents. For example, near-ground relative humidity and storm-relative helicity are important for tornadoes while buoyancy in below freezing temperatures and weak near-ground winds are important for large hail. Low-level moisture flux turned out to be the best discriminator between tornadoes and large hail events. However, despite these similarities, statistical analysis indicated that a predictive value for some ingredients can be markedly different among continents. A prime reason for that are different underlying climatological conditions. For example, a strong low-level wind shear combined with sufficient buoyancy is rare over Europe and Australia but when it occurs, it is often associated with tornado reports. On the other hand, a strong low-level wind shear is common over the United States, but is not always associated with proper convective organization to produce a tornado. For this reason, we believe that developing environmental models intended to work universally across the entire world can be extremely difficult as it is challenging to disentangle signals that are associated with physical processes from those that result from a local climatology.

How to cite: Taszarek, M., Allen, J., Nixon, C., Dowdy, A., and Battaglioli, F.: Do severe storms across Australia, Europe and the United States share similarities? A comparison of atmospheric profiles and environmental predictors, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-682, https://doi.org/10.5194/ems2023-682, 2023.

In the summer of 2021, the Swabian MOSES (Modular Observation Solutions for Earth Systems) field campaign was carried out in southwestern Germany. The campaign focused on the initiation and development of deep convective systems between the Black Forest and the Swabian Jura. During the campaign, the first measurements with a new airborne Doppler lidar system were conducted and a ground-based Doppler lidar network consisting of eight stations was deployed.

This contribution presents combined airborne and ground-based lidar observations which provide new insight into meso-scale flow processes in the vicinity of deep convective systems initiating in complex terrain. The unique spatial sampling characteristics of the airborne Doppler lidar are exploited to evaluate whether a quantitative retrieval of meso-scale convergence during convection initiation in complex terrain is possible and meaningful. The combination with radar observations provides context for the convective activity associated with the observed flow field. The convergence estimation approach is then also applied to the ground-based Doppler lidar network, providing also insight into the temporal evolution of the flow field.

The observations and convergence estimates are compared to the operational convective-scale analysis produced by the Icosahedral Nonhydrostatic modelling framework (ICON) of the German Weather Service. This facilitates the evaluation of the validity of assumptions inherent to the network-based convergence retrieval. Subsequently, the network-based convergence estimates can be used to gain insight into the analysis accuracy.

Overall, the influence of meso-scale convective systems on flow characteristics is detectable both in airborne and ground-based measurements. A quantitative estimation of convergence appears possible and can be used to enhance process understanding and improve model evaluation. The combination of airborne Doppler lidar measurements with a ground-based Doppler lidar network proves useful. While the former provides both extended spatial coverage and high resolution during intensive observation periods, the latter allows for temporally resolved observations over extended periods. Thus, together these measurement systems prove to be a suitable and promising technique to gain new insights into flow phenomena in the vicinity of convective systems in complex terrain.

How to cite: Gasch, P., Oertel, A., Hervo, M., and Team, T. S. M.: Convection initiation in complex terrain – can it be linked to meso-scale convergence?, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-124, https://doi.org/10.5194/ems2023-124, 2023.

Convection-permitting regional climate models (CPRCMs) have emerged as a promising approach to produce high-resolution climate simulations as they are able to better represent sub-daily temperature and precipitation patterns and extreme values compared with coarser- resolution convection parameterizing simulations.  However, to bridge the gap between the grid scale (1-4 km) of CPRCMs and local spatial scale (ground station), bias-correction is still needed. The objective of our work is to test a statistical downscaling technique on CPRCMs to produce bias-corrected precipitation for a future period at the station level. Quantile mapping (QM) was chosen because this empirical method is among the most reliable and straightforward bias correction techniques. The quantile mapping process was implemented between CPRCM outputs for the historical period (1998 – 2009) and the point-scale observations and then applied to sub-hourly precipitation for the future period (2078 – 2089) in Zurich, Switzerland. Kloten station in Zurich was chosen to implement the experiment. At the same time, a simple nonparametric quantile mapping approach was used for other hourly climate variables such as temperature, relative humidity, air pressure, global radiation, and wind speed. The climate extremes indices for temperature and precipitation were also calculated to analyze the long-term climate trends in the study site. According to our results, the climate change signals of both precipitation and temperature were not altered during bias adjustment and the inter-variable dependencies were also preserved. Nevertheless, limitations of our approach still remain and future work is needed to determine whether more advanced techniques can improve sub-daily predictions for multiple climate variables. 

How to cite: Nguyen Thi Quynh, T. and Cook, L.: Downscaling of convection-permitting simulated precipitation for future projection, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-217, https://doi.org/10.5194/ems2023-217, 2023.

This study selected three heavy-rainfall events of different types in the Mei-yu season in Taiwan for high-resolution simulations at a grid size of 1 km and assess the model’s capability to reproduce the morphology and characteristics of them. The three cases include a pre-frontal squall line, a mesoscale convective system (MCS) embedded in southwesterly flow, and a local convection near the front in southern Taiwan during the South-West Monsoon Experiment (SoWMEX) in 2008, chosen mainly because of the availability of the S-band polarimetric (S-Pol) radar observations, especially the particle identification results. The model used is the Cloud-Resolving Storm Simulator (CReSS), a cloud model that treats all clouds explicitly without any cumulus parameterization. 

The simulations using the CReSS model could reproduce all three corresponding rainfall systems at roughly the correct time and location, including their kinematic structures such as system-relative flows with minor differences, although the cells appeared to be coarser and wider than the S-Pol observations. The double-moment cold-rain microphysics scheme of the model could also capture the general distributions of hydrometeors, such as heavy rainfall below the updraft core with lighter rainfall farther away below the melting level, and graupel and mixed-phase particles in the upper part of the updraft with snow and ice crystals in stratiform areas between updrafts above the melting level. Near the melting level, the coexistence rain and snow corresponds to wet snow in the observations. Differences in cloud characteristics in the events are also reflected in model results to some extent. Overall, the model’s performance in the simulation of hydrometeors exhibits good agreement with the observation and appears reasonable.

How to cite: Wang, C.-C., Lan, Y.-Y., and Chen, Y.-H.: An Assessment of Cloud Microphysical Characteristics of Three Mei-yu Rainfall Systems in Taiwanas Simulated by A Cloud-Resolving Model, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-121, https://doi.org/10.5194/ems2023-121, 2023.

Extreme wind speed events cause more than half of the economic losses associated with natural disasters in Europe, and they are becoming more frequent and severe due to climate change. A better understanding of these extreme events is essential to reduce their associated risks. The overall aim of this research is to study the performance of different parametrizations (micro physics and planetary boundary layer) of the WRF model for the simulation of extreme wind speed and gusts events on the eastern coast of the Iberian Peninsula (IP), Spain. Two typical extreme wind events are simulated: (i) a cold front passage in winter (January 4^th, 2022), and (ii) a downburst in summer (August 15^th, 2021). Three 2-way nested domains are defined, the two largest ones (horizontal resolutions of 9- and 3-km) centered on the IP and the third one (1-km) centered on the Valencian region. The simulations are initialized with data from the ERA5 reanalysis and the boundary conditions in the coarser domain are updated hourly. The evaluation of the simulations is assessed by means of observed data provided by the Spanish State Meteorological Agency (AEMET) including automatic station network data, radar and satellite images and atmospheric soundings. The model accurately simulates the passage of the cold front, matching the time and magnitude of the observed wind speed and gusts. However, the WRF model does not reproduce the downburst, at least at the observed location. In general, the simulations are more sensitive to the choice of the boundary layer parameterization than to the microphysics parameterization.

How to cite: Utrabo-Carazo, E., Alvarez Imaz, M., Dillon, M. E., Garcia Skabar, Y., Aguilar, E., and Azorin-Molina, C.: Evaluation of WRF parameterizations for extreme wind events over the eastern coast of Spain, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-552, https://doi.org/10.5194/ems2023-552, 2023.

This presentation will showcase research conducted at the European Centre for Medium-Range Weather Forecasts (ECMWF) as part of the Destination Earth initiative of the European Commission. This initiative aims to develop a continuous global component of Earth's Digital Twin of Weather-induced and Geophysical Extremes (Extremes DT) to be able to forecast and monitor extreme weather events with unprecedented precision worldwide within a five-day range.

We will discuss various model experiments used to evaluate how horizontal resolution, ocean-atmosphere coupling, and different forecast initializations affect the prediction of some extreme weather events (i.e. medicanes, winter European storms, or extreme alpine precipitation, among others). In the current Extremes DT, ECMWF's Integrated Forecasting System cycle 48r1 is being used with a Tco2559 grid (approximately 4.5 km in horizontal resolution). We will compare the performance of these simulations with the current ECMWF's operational deterministic 9km forecasts and even higher resolution forecasts and we will validate the simulations with high-density observations and model analyses.

This research shows the significant benefits of higher resolution in predicting near-surface fields in specific case studies, especially large precipitation amounts in regions with complex orography, and the potential for more accurate medicane forecasts (both location and intensity). However, variables such as maximum wind gusts require additional development, such as enhancing data assimilation and reviewing parametrization formulations, and evaluation using high-density observations. For these goals to be achieved, we conclude that other aspects of global models need to be improved alongside increased resolution. Ultimately, our work provides valuable insights into evaluating and improving Earth System models on a kilometre-scale.

How to cite: Gascón, E., Maier-Gerber, M., Vannière, B., Irina, S., Magnusson, L., and Mogensen, K.: Towards a kilometre-scale Earth System Model to better predict extreme weather events: insights from the Destination Earth initiative's case studies., EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-66, https://doi.org/10.5194/ems2023-66, 2023.