Atmospheric particulate matter with an aerodynamic diameter < 2.5 µm (PM_2.5) is associated with adverse effects on the climate system, the human health, vegetation and the ecosystems. The World Health Organization (WHO) lowered the guideline limit for PM_2.5 in autumn 2021 and this is exceeded in many regions including rural and remote areas in mainland Europe. Measurements of the chemical composition of PM_2.5 is essential to assess the sources which contribute to PM_2.5 mass concentrations and to further design meaningful policies to tackle sources at their origin.

Here we report 6 years (2014- 2020) of PM_2.5 mass and chemical speciation at five remote sites across France belonging to the EMEP network (European Monitoring and Evaluation Programme). The seasonal and spatial variability of aerosol composition and source contributions based on the proximity of sources and long-range transport are discussed. Trends in PM_2.5 and the main components at the five locations were evaluated by means of random-forest modelling coupled with a de-weathering algorithm. This approach is advantageous as resulting trends are driven by changes in emission or atmospheric processes and not by changes in weather conditions and/or long-range transport patterns. Random-forest regression modelling was built using meteorological data, backtrajectory information and temporal variables at each site and quantified the most important factors that explain PM_2.5 concentrations at remote rural areas in France.

All sites observed statistically significant downward trends in PM_2.5 at a rate of -4 to -9% year^-1 for the period 2014 – 2020. The decrease in PM_2.5 concentrations was mostly explained by changes in the secondary inorganic species (sulphate, nitrate and ammonium) and not by changes in primary PM_2.5 emissions. The variability in trends in PM_2.5 and components observed across the sites is discussed with their implications for policy makers.

How to cite: Font, A., Bourin, A., Gouillou, C., Debevec, C., Bonnaire, N., Sauvage, S., F. de Brito, J., and Riffault, V.: Aerosol composition at EMEP remote sites in France : mass balance and de-weathered trends of PM2.5 and its main components, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-940, https://doi.org/10.5194/egusphere-egu23-940, 2023.

Fine particulate matter (PM_2.5) is one of the major atmospheric components that is responsible for poor air quality and adverse health and climate effects. An identification of both primary emission sources as well as secondary formation mechanisms of PM_2.5 is important to develop effective and efficient strategies to control and mitigate these adverse effects.

The COVID-19 pandemic had a significant impact on air quality across the globe through reduction in source emissions. This study examines the impact of the lockdown measures on PM_2.5 and its chemical composition in Bhopal, India by comparisons with pre-lockdown period. Positive Matrix Factorization (PMF) (Paatero and Tapper, 1994) is the most widely used approach for factor analysis-based source apportionment studies. In this study the EPA PMF program version 5.0, was used to solve the PMF model. A comprehensive suite of instruments was used to measure the 24-hour integrated PM_2.5 mass and its chemical composition collected onto various filter substrates every other day for two years (2019-2020) at Bhopal. This period coincides with the pre-lockdown, lockdown, and post-lockdown phases in India. The mass concentrations during the study period ranged between 54.7 µg m^-3 during pre-lockdown and 45.1 µg m^-3 in lockdown phase. PMF5 was applied to a dataset of organic and elemental carbon fractions (OC1, OC2, OC3, OC4, OP, EC1, EC2, EC3), nine major water-soluble inorganic components namely F^-,Cl^-, NO₃^- ,SO₄^-2,Na⁺, NH₄⁺,Mg⁺², K⁺, Ca⁺², and elements (Al, Mg, Ca, Si, P, K, V, Ti, Co, Ni, Cu, As, Cr, Cd, Fe, Ni, Zn, Se, Sb, Ba, Pb) were used in the analysis.

Overall, the combined datasets (2019-2020) approach helped in better model resolution as several zeroes were present in both the loading and score matrices compared to a model run with 2019 data alone. An 8-factor solution was resolved with factors identified as coal and gasoline combustion, biomass burning, secondary sulfate, secondary nitrate, re-suspended crustal dust, diesel emissions, brick kiln emissions and mixed industrial emissions. Further, assessment of the pre-COVID and lockdown scenarios revealed a decreased in the mass contribution of diesel emissions (21.3%), mixed industrial emissions (13.7%), secondary sulfate (10.6%) and secondary nitrate (4.7%) during the lockdown phase compared to the pre-lockdown period at the study site. However, there was no decrease in the biomass burning source contribution due to no curbs on agricultural activities during the lockdown period in India. Overall, this study provides key insight into the source composition and contribution variations due to the reduction of specific anthropogenic source emissions due to COVID-19 lockdowns. Further, it is an added impetus for policymakers to implement targeted strategies and regulations, to reduce local and regional air pollution.

How to cite: Pullokaran, D., Sunder Raman, R., Bhardwaj, A., Shukla, D., and Haswani, D.: Insights into the impact of COVID-19 lockdowns on USEPA PMF-5 derived PM2.5 source contributions at Bhopal, India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12077, https://doi.org/10.5194/egusphere-egu23-12077, 2023.

Our globalised world, with its many acute natural and social problems, has now created all the conditions for pandemics. The COVID-19 pandemic is the first real manifestation of this in our modern history, affecting every geographical region, every social class and almost every single economic sector. The spread of the epidemic, which was accompanied by extremely severe social and economic devastation and damage, was sanctioned by reducing people's social activity and high mobility. The measures have also been accompanied, obviously, by a reduction in some of the environmental stresses resulting from anthropogenic activity.

Our research investigates the relationship between satellite remote sensing air pollution data and sanctions related to the coronavirus epidemic, taking into account complex physical- and socio-geographical factors. Spatially and temporally differentiated COVID-19 sanctions and lockdowns (home office orders, curfews, service closures, shutdowns) have different atmospheric environmental impacts in different physical geographic regions (topography and circulation, vegetation cover, natural aerosol loads, etc.) and in areas with different socio-economic characteristics. Our aim was to identify the individual effects of the complex processes underlying the changes in atmospheric environment indicators that have not been observed before.

In this paper, NO₂ and atmospheric aerosol are presented in detail, with a clear distinction between atmospheric substances of purely anthropogenic origin and those typically interpreted as natural pollutants (e.g. Saharan dust). A comparative analysis of these, using data from 2019, 2020 and 2021, highlights the spatiotemporal characteristics of the period before, during and after COVID-19 sanctions. For this purpose, Sentinel-5p and MODIS Aerosol Optical Depth data were used. The different changes in the air environment in Western and Eastern European countries, and in particular in some industrial regions, are clearly visible in the series of maps presented.

The research was supported by the project POST-COVID2021-29 of the Hungarian Academy of Sciences.

How to cite: Varga, G., Csávics, A., and Gresina, F.: Complex geographical causes of different levels of air pollution changes caused by COVID-19 sanctions in Europe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8845, https://doi.org/10.5194/egusphere-egu23-8845, 2023.

It is well known that in the climate and air quality studies, the monitoring process of aerosols and their temporal evolution is very important as they generate a significant impact on meteorology, air quality, climate, and human and ecosystem health. In this study, we present an overview of aerosol optical and microphysical properties over Cluj-Napoca, Romania- based on more than 12 years of observations from a Cimel sun-photometer operating in the framework of AErosol RObotic NETwork (AERONET) and part of the Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS). This site is located in the north-western part of Romania and contributes to AERONET with sun photometer observation since 2010. As the atmosphere in the region is characterized by a mixture of aerosols from multiple sources: urban/industrial (dominant) biomass burning, Saharan dust, etc., this study aims to present the aerosol trends and the temporal variation of their properties based on long-term observations. The analysis highlighted that the aerosol load over the area is characterized by high inter-annual and seasonal variation of AOD due to variation of local sources and long-range transport. The same variability was observed for the Ångström Exponent, suggesting the presence of aerosols of different sizes. The methods used in this study can be extended to other stations for identifying the long-term variability of aerosols.

How to cite: Radovici, A., Stefanie, H., Mereuta, A., Camarasan, H., Botezan, C., Costin, D., and Ajtai, N.: Climatology and trends derived from columnar aerosol measurements in Cluj-Napoca, Romania., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-193, https://doi.org/10.5194/egusphere-egu23-193, 2023.

Multiwavelength aerosol optical depth (AOD) has been defined as an essential climate variable for the Global Climate Observing System (GCOS) and the Global Atmosphere Watch (GAW) Program of the World Meteorological Organization. It is the most important parameter related to aerosol radiative forcing studies. PMOD/WRC have developed the Precision Filter Radiometer (PFR) that has been used for long term AOD measurements under a GAW-PFR Network of sun-photometers started in 1995 at Davos Switzerland and from 1999 at other locations, worldwide.

Here we present an overview of the stations measurements till 2021 including station statistics and AOD trends.

An overview of the results of the long term GAW-PFR AOD series for four high altitude stations (Izana/Spain, Mauna Loa/USA, Mt. Walliguan/China and Jungfraujoch/Switzerland). Mean AODs at 500nm were from 0.01 up to 0.1 with small negative changes per year for all stations.

Also we present an overview of the homogenization activities performed by the world aerosol optical depth research and calinration center (WORCC) towards a harmonization of AOD measurements worldwide and some examples on uncertainties and effects on global trend analysis and satellite AOD validation initiatives.

How to cite: Kazadzis, S., Kouremeti, N., and Groebner, J.: Aerosol Optical Depth Measurements and trends from the  Global Atmospheric Watch - PFR Network and aerosol homogenization initiatives, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2340, https://doi.org/10.5194/egusphere-egu23-2340, 2023.

The accumulation of both particulate matter (PM₁₀, PM_2.5) and gaseous species (NO₂, CO, SO₂, O₃) in the atmosphere in urban agglomerations can cause a significant degradation of air quality. The additional impact on human health, visibility, cultural heritage and urban climate has been recognized in studies worldwide. This study represents an air quality assessment in the urban agglomeration of Ploiesti, which is located north of Bucharest (the highest polluted city of Romania), in the central-northern part of Romanian Plain. In Ploiesti operates some of the most important refineries of the country. The city also represents an important link between Bucharest and south of Romania and the northern and western parts of the country.

The study is focused on major air pollutants, particulate matter (PM₁₀, PM_2.5), and also gaseous species (NO₂, CO, SO₂, O₃) at six monitoring sites (traffic, industrial and background). To highlight temporal and spatial variations, a synthetic database covering a four-year period (2018-2021) consisting of time series of hourly and daily values of major air pollutants mass concentrations were statistically investigated. To analyze the influence of meteorological conditions on the air quality in Ploiesti area meteorological observations was constructed.

Present research shows that although Ploiesti is significantly smaller than Bucharest, the anthropogenic activity in Ploiesti strongly affects atmospheric pollution levels on daily timescales (multiannual mean ratio PM_2.5/PM₁₀ = 0.71) at almost same level that in Bucharest area. Additionally, we found the central area impact on surroundings is major, as significant differences were not identified.

We identified both local and regional pollution episodes, but also episodes strongly influenced by the long-range transport of dust pollution.

PM₁₀ pollution roses showed the dominance of local pollution sources in most of the time. On shorter timescale, the long-range transport of fine particulate matter coming from desert dust (Saharan or from Middle East deserts) contributed supplementary to increased pollution as we identified in 13 episodes (during 2018-2021). It has been shown that the atmospheric stability has an important role in the accumulation of PM₁₀ at the scale of Ploiesti urban agglomeration. Trend analysis of annual pollutant mass concentrations for all air quality stations was performed using a larger dataset, since 2008 (first monitoring year) to present (end of 2021), using Mann-Kendal and Sen’slope analysis. Diurnal profile of particulate matter PM₁₀ and the influence of the lockdown restrictions in spring 2020 on PM₁₀ levels were also quantified.

Acknowledgment

The research leading to these results has received funding from the NO Grants 2014-2021, under Project contract no. 31/2020, EEA-RO-NO-2019-0423 project. Data regarding ground-level air pollution and local meteorology by site was extracted from the public available Romanian National Air Quality Database, www.calitateaer.ro, last accessed in December 2022. Meteorological data were extracted from Copernicus Climate Change Service (C3S) Climate Data Store (CDS) ERA5 hourly data on single levels and pressure levels from 1959 to present https://cds.climate.copernicus.eu (last accessed in December 2022).

How to cite: Mihalache, B., Colt, M., Stefan, S., and Iorga, G.: A comprehensive study on atmospheric pollution over Ploiesti, Romania, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3209, https://doi.org/10.5194/egusphere-egu23-3209, 2023.

Abstract

It has been proven that air pollution is closely related to the level of socio-economic development of a country. Various levels of development generate different level of by-products, including air pollution, deteriorating therefore the air quality at regional levels in peculiar ways. Romania is the largest country in southeastern Europe with a very complex economic development level and air pollution disparities among cities.

This paper aims to study main socio-economic indicators (as measures of the effect of human activities on air pollution and climate) for over 30 cities in Romania with diferent levels of economic development, to determine the relationship between these variables and air pollution condition. We focused on the spatial relationship between main gaseous air pollutants and the following indicators GDP, GDP/capita, resident population, number of private vehicles and life expectancy.

In this research we created two data sets as follow: first one consists of daily values of air pollutant (CO, NO₂, O­­₃, SO₂) mass concentrations extracted from the Romanian National Air Quality Network and the second set consists of socio-economic indicators (GDP, GDP/capita, resident population, number of private vehicles and life expectancy) obtained from Romanian National Institute of Statistics. The study was conducted over five years, from 01.01.2016 to 31.12.2020 using yearly means of air pollutants from the first dataset in all selected urban areas in the Romanian territory and corelate them with the socio-economic indicators from the second data set using univariate LISA and bivariate LISA statistical analysis methods.

The analysis demonstrated the correlation of socio-economic indicators with the increase of the air pollution in the study area. Other highlights of the study: (a) Range of major air pollutant levels in 30 urban agglomerations across Romania from 2016 to 2020 was assessed (b) Maps of interpolated mass concentrations reveal regional significant differences with pollutant-specific hot- and cold-spots in Romania. Regional significant differences can be observed; (c) Results show pollution decreases for most pollutants in most cities in 2020 due to pandemic restrictions.

The results of present study can be beneficial to local authorities in order to help them in their decisions for abatement pollution strategies at the country scale combined with regional measures.

Acknowledgment

The research leading to these results has received funding from the NO Grants 2014-2021, under Project contract no. 31/2020, EEA-RO-NO-2019-0423 project. Data regarding ground-based air pollutants were extracted from the Romanian National Air Quality Database, www.calitateaer.ro. Economy indicators were provided by National Institute of Statistics http://statistici.insse.ro:8077/tempo-online/. Databases were last accessed in December 2022.

How to cite: Chiritescu, R. V. and Iorga, G.: Air pollution over Romania: spatial relationship betweensocio-economic indicators and air pollutants using univariate and bivariate local indicators, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4913, https://doi.org/10.5194/egusphere-egu23-4913, 2023.

Within the framework of the EUMETSAT AC SAF project, the production of climate data records (CDRs) of short lived O₃ precursors (HCHO and NO₂) is under development, based on the three GOME-2 instruments and the future S5 and S4 Copernicus platforms.

This work presents the development of the formaldehyde CDR, combining the current GOME-2 A, B and C operational AC SAF Level-2 orbital products to create one single L3 averaged product using advanced gridding tools. To this aim, the consistency between the three GOME-2 instrument needs to be improved by means of suitable correction schemes accounting for inter-sensor biases due to inconsistent auxiliary data or instrumental issues. The use of the CAMS model reanalysis as a source of prior HCHO profiles is explored with the aim to produce one consistent dataset from 2007 to now. Estimation of the random and systematic uncertainty is included for each grid cell. Furthermore, we plan to include meteorological re-analysis data (surface temperature and winds) in the output files to further support the interpretation of the data and of their observed variations.

Validation results of this new monthly averaged CDR dataset will be presented, with a special focus on bias, precision and stability in time. To this aim, long-term ground-based HCHO measurements are collected and assessed.

How to cite: De Smedt, I., Pinardi, G., Valks, P., Heue, K.-P., Compernolle, S., Van Gent, J., Vlietinck, J., Yu, H., Loyola, D., Theys, N., and Van Roozendael, M.: Development of a merged HCHO climate data record from the EUMETSAT AC SAF GOME-2 Level-2 products, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7891, https://doi.org/10.5194/egusphere-egu23-7891, 2023.

We present two inventories of anthropogenic emissions as well as an air quality atlas linked to Copernicus, the European earth observation system. CAMS-GLOB-ANTv5.3, a global anthropogenic emissions inventory, has been developed and provides emission data for the major atmospheric pollutants and greenhouse gases, as well as 25 speciated Volatile Organic Compounds (VOCs), for the period 2000-2023. This inventory is used as input for the Copernicus Atmosphere Monitoring System (CAMS) atmospheric reanalysis and forecasts.

A mosaic inventory of anthropogenic emissions was also developed as part of the Copernicus CO₂ project (CoCO2) focusing on greenhouse gases emissions. This mosaic uses the CAMS-GLOB-ANTv5.3 inventory as a global basis, and the DACCIWA2 (Dynamics-Aerosol-Chemistry-Cloud interactions in West Africa) inventory, a regional African emissions inventory. DACCIWA2 provides 0.1x0.1 degree resolution emissions of greenhouse gases and atmospheric pollutants for the period 2010-2018.

The CAMS reanalysis is being used to develop an atlas of air quality called AQWA (Air Quality Worldwide Atlas). The AQWA atlas gives precious information about historical, climatological and current atmospheric composition, as well as air quality indexes. These statistics are available for all countries around the world, as well as states/provinces for the United States and China.

This presentation describes the methodology used to develop and evaluate the two inventories and shows a few visualization examples from the atlas, which is still in development.

How to cite: Soulie, A., doumbia, T., Keita, S., Granier, C., Denier Vand der Gon, H., Kuenen, J., Arellano, S., Darras, S., Gauss, M., Guevara, M., Jalkanen, J.-P., Liousse, C., Simpson, D., and Sindelarova, K.: Global and regional anthropogenic emissions inventories for air quality atlases, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3232, https://doi.org/10.5194/egusphere-egu23-3232, 2023.

Air quality is not only dependent on emissions, but on climate and meteorology as well. This makes the study of the evolution of air pollution varying some of its drivers crucial. In this study, the present day and near future air quality in Central Europe is studied following RCP4.5 and RCP8.5 scenarios for the 2026-2035 and 2046-2055 decades, while considering present-day climate conditions. We assume that the climate changes a little while the main driver for air-quality changes in near future are the modified emissions. The emission input for the 2010-2019 decade were compiled using the Flexible Universal Processor for Modeling Emissions (www.fume-ep.org), and the two future decades are being prepared by scaling the present day emissions based on the mentioned RCPs. We are performing simulations using the Weather Research and Forecast with online chemistry version 4.0.3 (WRF-Chem) model and the Comprehensive Air-quality Model (CAMx). Several pollutants and meteorological variables will be studied and compared with observational data.

How to cite: Prieto Perez, A. P., Huszar, P., and Karlicky, J.: Modelling the near future air-quality over Central Europe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5673, https://doi.org/10.5194/egusphere-egu23-5673, 2023.

Ammonia (NH₃) is one of the most common nitrogen gas species and pollutants present in the lower troposphere. Ammonia enters the atmosphere through volatilisation from soils through the usage of nitrogen-based fertilisers in agriculture [1]. Because of its short lifetime (up to a few hours) [2], ammonia is highly reactive and can react chemically with acids in the atmosphere to form fine particulate matter (PM_2.5), playing an important role in secondary aerosol formation [3]. Wet and dry deposition of ammonia on soils and water bodies has shown to be detrimental to ecosystem biodiversity as it leads to acidification of the environment [3]. Therefore, observations of ammonia are essential for establishing air quality and environmental regulations for agricultural practices.

By using combined satellite measurements from the Infrared Atmospheric Sounding Interferometer (IASI) and the Cross-track Infrared Sounder (CrIS) instruments, we aim to study trends and the diurnal cycle of ammonia on regional scales, particularly in areas subjected to intensive agricultural activity, such as the Indo-Gangetic Plain (northern India). This research makes use of an optimal estimation-based method of monitoring ammonia with satellites called the University of Leicester IASI retrieval Scheme (ULIRS).

References:

[1] Van Damme M. et al (2021), Environ. Res. Lett., 16 055017

[2] Dammers E. et al (2019), Atmos. Chem. Phys., 12261–12293

[3] Erisman, J. W. et al (2007), Environ. Pollut., 150, 140– 149

How to cite: Iorga, A., Harrison, J., and Moore, D.: Air Pollution from Agriculture: Using Satellite Observations to Study Ammonia Emissions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2755, https://doi.org/10.5194/egusphere-egu23-2755, 2023.

In recent times, Surface Ozone has become a widely studied constituent due to its emergence as a short-lived secondary pollutant and its damaging impacts on human health and crop production. Recent studies show increased surface ozone across different parts of the world including the Indian region. The modern reanalysis dataset provides meteorological parameters as well as atmospheric chemical compositions such as tropospheric ozone etc. In this study, we validated the spatial-temporal ozone variability using ground-based observation and reanalysis datasets such as over the North-west Indo Gangetic region. Reanalysis datasets are the Copernicus Atmospheric Monitoring Service reanalysis (CAMSRA) and NASA Modern-Era Retrospective analysis for Research and Application version 2 (MERRA2) which tells the spatial-temporal variability of surface ozone over the Northwest region of India. The result shows a lesser correlation over the study region. Through a validation process, it was determined that the CAMSRA compares fairly to ground-based observations with correlations (> 0.5)  over the Northwest region of India. This agreement has also been quantified in terms of range, Mean Absolute Error (MAE), and Root Mean Square Error (RMSE). The CAMSRA captures seasonal variations regardless of location, according to a time series analysis. Spatial distribution of surface ozone shows higher concentration during pre-monsoon followed by post-monsoon. Over the northwest region, a notable rise is noticed during May over the Indo-Gangetic Plains in particular (IGP) of the Indian region. These seasonal differences are associated with solar radiation (SR), temperature, low-level circulation, and boundary layer height (BLH).In order to further examine the spatial and temporal variability of surface ozone, we have performed the Principal Component Analysis (PCA). PCA explains the relationship between dominant modes of spatial variability and their temporal evolution. Overall, the findings show that variations in the precursors or in the meteorological conditions have a considerable impact on the surface ozone concentrations across the northwest region of India.

How to cite: Saroj, P., Ghosh, C., and Singh, S.: Evaluation of surface ozone variability using ground-based observation and reanalysis dataset over the North-West Indo-Gangetic Plain of Indian region., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-660, https://doi.org/10.5194/egusphere-egu23-660, 2023.

Stratosphere-to-troposphere transport (STT) is an important source of ozone for the troposphere, particularly over western North America. STT in this region is predominantly controlled by a combination of the variability and location of the Pacific jet stream and the amount of ozone in the lower stratosphere, two factors which are likely to change if greenhouse gas concentrations continue to increase. Here we use Whole Atmosphere Community Climate Model experiments with a tracer of stratospheric ozone (O3S) to study how end-of-the-century Representative Concentration Pathway (RCP) 8.5 sea surface temperatures (SSTs) and greenhouses gases (GHGs), in isolation and in combination, influence STT of ozone over western North America relative to a preindustrial control background state.

            We find that O3S increases up to 39% at 700 hPa over western North America in response to RCP8.5 forcing with the largest increases occurring during late winter and tapering off during spring and summer. The GHGs are primarily responsible for these tropospheric O3S changes. Both the future SSTs and the future GHGs accelerate the Brewer Dobson circulation, which increases extratropical lower stratospheric ozone mixing ratios. While the GHGs promote a more zonally symmetric lower stratospheric ozone change due to enhanced ozone production and some transport, the SSTs increase lower stratospheric ozone predominantly over the North Pacific via transport associated with a stationary planetary-scale wave. Ozone accumulates in the trough of this anomalous wave and is reduced over the wave’s ridges, illustrating that the composition of the lower stratospheric ozone reservoir in the future is dependent on the stationary planetary-scale wave response to future SSTs. In addition, the future SSTs are found to prompt most changes to the large-scale circulation in the troposphere and stratosphere compared to the effect of the GHGs. These changes include modifying the position and speed of the future North Pacific jet, lifting the tropopause, accelerating both the Brewer-Dobson Circulation’s shallow and deep branches, and enhancing two-way isentropic mixing in the stratosphere.

How to cite: Elsbury, D., Butler, A. H., Albers, J. R., Breeden, M. L., and Langford, A. O.: The response of the North Pacific jet and stratosphere-to-troposphere transport of ozone over western North America to RCP8.5 climate forcing, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3498, https://doi.org/10.5194/egusphere-egu23-3498, 2023.

Current approaches to estimate NO_x emissions fail to account for new and small sources, sources with large spatial and temporal variability, and sources which have significantly changed. Furthermore, the current generation of NO_x emissions estimates don’t provide a sufficiently robust uncertainty analysis. They tend to use a fixed combination of localized models (in space and time), and do not adequately consider the variability in observed chemistry, dynamics, and thermodynamics. This work introduces a new, model-free analytical approach that assimilates daily-scale remotely sensed tropospheric columns of NO₂ from TROPOMI in a mass-conserving manner, to invert daily NO_x emissions. This approach is flexibly applied over a rapidly developing and energy-consuming region of Northwest China which is chosen due to substantial economic and population changes, new environmental policies, large use of coal, and access to independent emissions measurements for validation [EGT]. It is also applied over two densely urbanized regions, as well as their surrounding rural and rapidly developing outer suburban regions, including the Pearl River Delta and the Yangtze River Delta, both of which are chosen due to the amount and variability of sources, rapid economic development, and strong changes in environmental emissions policy and regulation. Over the EGT area, this technique computes a net NO_x emissions gain of 70% distributed in a see-saw manner: emissions are more than doubled in cleaner regions, at chemical plants, and in regions thought to be emissions-free, while at the same time, emissions are more than halved in city centers and at other well-regulated and large commercial locations such as steel smelters and powerplants. There is a considerable amount of NO_x emissions observed in suburban areas and rapidly developing rural areas, while a priori datasets do not account for these sources. A few interesting scientific points are explained in detail. First, the error over land surfaces which are not changing is smaller than the day-to-day variability, supporting the idea that daily variability is essential. The errors over areas undergoing land-use change and water are similar to or larger than the day-to-day variability. Second, source attribution is quantified with respect to the local thermodynamics of the combustion temperature, with measured atmospheric transport, and with in-situ chemical processing. Third, there are a significant number of sources identified which do not exist in the a priori datasets, but which are consistent with surface observations. Fourth, sensitivity runs are performed which account for the wide-range of uncertainty estimates of TROPOMI and the self-consistency of the estimated emissions is analyzed on a grid-by-grid and day-by-day basis, showing that the physically realistic constrains on the first order differential equation terms and bootstrapping approach are robust. It is hoped that these findings will drive a new approach to emissions estimation, one in which emissions are based consistently on remotely sensed measurements and associated uncertainties. Such approaches are essential in rapidly developing regions and in the Global South, where local measurements do not otherwise exist.

How to cite: Lu, L., Qin, K., and Cohen, J. B.: Computing Daily NOx Inversion over Energy Consuming and Urbanized Regions Using TROPOMI Data – A Novel Model Free Approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10999, https://doi.org/10.5194/egusphere-egu23-10999, 2023.

Atmospheric chemistry models play a major role for relating greenhouse gases and pollutants concentrations to emissions at high temporal resolutions over large areas. On that account, it is fundamental to use up-to-date anthropogenic emissions maps as model inputs. Despite efforts by researchers to create global emission datasets with high temporal resolutions, for countries with no national data, generic activity maps and emission factors are used, thus the accurate representation of the anthropogenic emissions in a local scale still remains challenging. This study presents an improved spatially explicit dataset for anthropogenic emissions of CO2 and NOx over the Middle-East, a region characterized by extensive gas power plants and heavy industries operations. Our dataset was developed by combining a detailed infrastructure map for point sources in the area and it is used to simulate the distribution of CO2 and NO2 using the WRF-Chem mesoscale atmospheric transport chemistry model. Furthermore, the chemistry scheme of the WRF-Chem model in the simulation of CO2 and NO2 plumes is examined, in comparison with satellite observations.
   
In the framework of the Eastern Mediterranean and Middle East – Climate and Atmosphere Research (EMME-CARE) project, our new detailed infrastructure map for power plants and gas flaring has been implemented in WRF-Chem simulations for the Middle-East region to complete the Emission Database for Global Atmospheric Research (EDGAR) as input. The EDGAR data consists of emissions by various sectors such as power plants, industry, residential, transportation and agriculture. Furthermore, hourly scaling factors have been applied to the anthropogenic emissions according to the electricity consumption of the particular urban areas, taking into account the weekly as well as the monthly variations. The periods under study are January 2021 and June 2021. By comparing the WRF-Chem outputs to TROPOMI satellite observations for NO2, the results show that the addition of point sources was crucial for the detection of some NO2 plumes. Moreover, the WRF-Chem model systematically overestimated the NO2 concentrations in the area with the current EDGAR dataset, therefore we introduced a new relationship between monthly and annual emissions for the Middle-East region. By carrying out WRF-Chem simulations with NO2 acting as a passive tracer it was also possible to examine the impact of the model chemistry in NO2 plumes development. Finally, CO2 was also simulated by the WRF-Chem model as a passive tracer and the results showed a good agrement with XCO2 data observed by the OCO-2 and OCO-3 instruments.

How to cite: Cheliotis, I., Lauvaux, T., Lian, J., Christoudias, T., Georgiou, G., Chevallier, F., Lei, R., and Ciais, P.: Optimization of simulated CO2 & NO2 concentrations for a detailed infrastructure map in the Middle East, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9518, https://doi.org/10.5194/egusphere-egu23-9518, 2023.

In Japan, concentrations of precursors of photochemical oxidants such as nitrogen oxides (NOx) and non-methane hydrocarbons (NMHCs) are decreasing year by year, but an improvement regarding photochemical oxidants is recently stagnant. To elucidate the reason, we have planned seasonal intensive observations in Tokyo, in which comprehensive measurements of speciated reactive nitrogen NOy and non-methane volatile organic compounds are performed. In summer of 2022, the observation was carried out at a campus of Tokyo Metropolitan University, a suburban area of Tokyo. In the intensive observation, NO, NO₂, ΣPANs, ΣONs, HONO, HNO₃, H₂O₂, SO₂, O₃, NH₃, 28 NMHCs, and 10 oxygenated volatile organic compounds (OVOCs) were measured simultaneously. The ΣPANs and ΣONs were measured by thermal dissociation-cavity attenuated phase shift (CAPS) spectroscopy. The HONO, HNO₃, and H₂O₂ were measured by negative ion chemical ionization mass spectrometry using I⁻·(H₂O)_n as the reagent ion. The NMHCs, OVOCs and NH₃ were measured by selected ion flow tube mass spectrometry and the data of NMHCs were compared and corrected with the data from gas chromatography/flame ionization detector (GC/FID). The ozone formation in Tokyo will be discussed.

How to cite: Inomata, S., Tanimoto, H., Matsumoto, J., Sadanaga, Y., and Kato, S.: Comprehensive measurements of speciated reactive nitrogen NOy and non-methane volatile organic compounds in Tokyo, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11532, https://doi.org/10.5194/egusphere-egu23-11532, 2023.

Volatile organic compounds (VOCs) are important gaseous constituents in the troposphere, impacting local and regional air quality, human health, and climate both directly and indirectly (IPCC, 2013). With the participation of nitrogen oxides (NO_x), oxidation of VOCs leads to tropospheric ozone (O₃) formation, causing regional photochemical smog (Atkinson, 2000). In recent years, with the decline of ambient concentrations of other pollutants (e.g., fine particulate matter), the concentrations of O₃ in many locations increased. Therefore, accurately apportioning the emission sources of ambient VOCs and then controlling them more effectively will play an important role in reducing O₃ and secondary organic aerosol pollution in the atmosphere and improving public health.

  In this study, field measurements were conducted at a coastal site (Hok Tsui; HT) in Hong Kong from October to November 2020 with proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOF-MS). VOC data coupled with air mass back trajectory cluster analysis and receptor modelling were applied to discuss the pollution pattern, regional transport, and emission sources of ambient VOCs at Hok Tsui in autumn 2020. Seven sources were identified from positive matrix factorization (PMF) analysis, namely vehicular + industrial, solvent usage, primary oxygenated VOCs (OVOCs), secondary OVOCs 1, secondary OVOCs 2 (aged), biogenic emissions, and background + biomass burning, contributing on average to 20.8%, 10.5%, 13.1%, 33.6%, 6.7%, 4.3%, and 10.9% of total VOC mixing ratios, respectively. Secondary OVOCs and vehicular + industrial emissions are the vital sources of ambient VOCs at Hok Tsui supersite. Integrated with backward trajectory analysis, long-range transport of air masses from inland and coastal regions of Southeast China brought more hydrocarbons from vehicular and industrial sources, and consequently more OVOCs in aged air masses. The results of this study highlighted the regional transport of anthropogenic VOCs should be considered in control strategies of VOCs and secondary air pollutants.

How to cite: Yuan, Q., Wang, M., Wang, T., and Lee, S.: Source characterization of VOCs at a coastal site in Hong Kong, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10637, https://doi.org/10.5194/egusphere-egu23-10637, 2023.

Sulfur dioxide (SO₂) plays a pivotal role in the chemistry of the troposphere, ultimately affecting the Earth’s radiation balance and climate. Within the atmosphere, SO₂ is oxidised by gas- and aqueous-phase chemistry to sulfate and is therefore a major precursor to atmospheric aerosols, particularly in the remote marine atmosphere. Both the direct radiative forcing from aerosols and the indirect forcing from aerosol-cloud interactions are poorly understood and produce large uncertainties in climate models. Therefore, it is of interest to precisely quantify the concentration of atmospheric SO₂ if we are to predict the effects of changing emission rates on both climate and air quality.

Anthropogenic SO₂ emissions have fallen dramatically in recent decades, resulting in significant reductions in atmospheric concentrations. Current commercial SO₂ detection techniques, for example pulsed fluorescence, are no longer sensitive enough to detect trace levels of SO₂ such as those found in remote marine environments. We report the development of a laser-induced fluorescence instrument for in situ SO₂ measurements using a custom-built, tunable fiber-amplified laser system. Based on the system initially developed by Rollins et al. (2016), the University of York LIF-SO₂ system has a detection limit of 50 ppt for 30 seconds and its relatively small size, weight and power requirements makes this instrument suitable for a variety of field campaigns.

Here we present aircraft measurements of SO₂ made by the York LIF-SO₂ instrument on board the UK FAAM research aircraft in both the remote and polluted marine boundary layer. These are then compared to simultaneous SO₂ measurements made by the University of Manchester I^- chemical ionisation mass spectrometer (I^- CIMS) instrument and the FAAM pulsed fluorescence commercial SO₂ detector.

How to cite: Temple, L., Young, S., Bannan, T., Batten, S., Bauguitte, S., Coe, H., Lee, J., Matthews, E., Pasternak, D., Rollins, A., Vallow, J., and Edwards, P.: A Comparison of Aircraft SO2 Measurements in Remote and Polluted Marine Environments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11726, https://doi.org/10.5194/egusphere-egu23-11726, 2023.

Merging data records from different instruments into a consistent long-term data record is challenging process, especially when the parent datasets have a very short overlap or do not overlap at all. In addition, parent datasets can have different vertical resolutions and temporal and spatial samplings. In these cases, there is a need for a transfer standard - an independent data record that overlaps with parent datasets, allowing to characterize differences between the parent datasets and to derive absolute adjustments. In this study we discuss requirements for the transfer standard including long-term stability, spatial and temporal sampling. We estimate how various properties of the transfer standard affect stability of the merged record and derived long-term trends. We assess the impact of the transfer function on the trends of merged datasets from satellite observations, on the examples of merging ozone records from SAGE II / MIPAS / OMPS NASA and temperature records from HALOE / MIPAS, using EMAC, CMAM and WACCM model fields as transfer standards.

How to cite: Laeng, A.: Creating long-term climate data records using transfer functions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13965, https://doi.org/10.5194/egusphere-egu23-13965, 2023.

Water vapour in the upper troposphere and stratosphere has a significant impact both on the radiative and chemical properties of the atmosphere.  Reliable water vapour climate data records (CDRs) are essential for use in climate research, to assess vertically resolved trends and associated radiative impacts. Within the ESA Water Vapour Climate Change Initiative (WV_cci), new vertically resolved water vapour CDRs in the stratosphere and UTLS were merged from a range of satellite observations. In this contribution, we provide an overview of these CDRs, highlighting innovations in the merging methodologies and results from a detailed quality assessment. In particular, the long-term trends derived from the new water vapour CDRs are compared to other merged datasets, reanalyses, and simulations from chemistry-climate models, with the ESA WV_cci CDRs deemed to be valuable new datasets for climate studies.  We conclude that, mostly driven by dynamical variability, the derived water vapour trends vary significantly depending on the dataset used, chosen time period and location in the atmosphere. Using an off-line radiative transfer model, we estimate the consequence of these differences on the radiative forcing from water vapour changes in the upper troposphere and stratosphere over the past 30+ years.

How to cite: Ye, H., Hegglin, M., Hubert, D., Lambert, J.-C., Walker, K., Sioris, C., Millan, L., Manney, G., Froidevaux, L., Kerridge, B., Siddans, R., Wang, R., Plummer, D., Krämer, M., Rolf, C., and Shine, K.: Long-term trends and radiative impact in vertically resolved stratospheric water vapour from ESA WV_cci data records, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9271, https://doi.org/10.5194/egusphere-egu23-9271, 2023.

The Atmospheric Chemistry Experiment – Fourier Transform Spectrometer (ACE-FTS) is a high spectral resolution (0.02 cm^-1) spectrometer on the SciSat satellite that has been taking solar occultation measurements of the Earth’s limb since February 2004. ACE-FTS measures vertical profiles of temperature/pressure and concentrations of over 60 trace gases, including ozone and water vapour, with a vertical resolution of ~2-6 km. From the beginning of the mission, ACE-FTS water vapour data exhibits a significant positive trend on the order of a few percent per decade throughout the stratosphere and mesosphere, in agreement with similar measurements from the Microwave Limb Sounder (MLS) and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instruments. This study will investigate the link between ACE-FTS water vapour trends and decadal variations in other atmospheric parameters, including local and tropopause temperatures, ozone and methane concentrations, and solar flux, and will discuss how ACE-FTS measurements of HDO can be used to continue measuring background water vapour trends post-eruption of the Hunga Tonga-Hunga Ha’apai volcano, which injected ~160 Tg of water vapour (more than 10% of the stratospheric water vapour budget) into the stratosphere.

How to cite: Sheese, P., Walker, K., Jeffery, P., and Boone, C.: ACE-FTS water vapour trends in the stratosphere-mesosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9414, https://doi.org/10.5194/egusphere-egu23-9414, 2023.

Water vapour is the most important greenhouse gas in the Earth’s atmosphere, both, due to radiative forcing and the formation of clouds. The upper troposphere and lowermost stratosphere (UTLS) region is an especially sensitive region for climate radiative forcing. In the UTLS the air is cold with a large spatial and temporal variability of water vapour.  With the MOZAIC (Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft) data it was recently shown that in the extratropical UT close to the tropopause the air is nearly saturated with respect to ice and contains a significant fraction of ice-supersaturated regions (ISSRs) (Petzold et al., ACP, 2020, doi.org/10.5194/acp-20-8157-2020).

In the present study we investigate the long-term changes of water vapour in the tropopause region using the combined time series of MOZAIC and IAGOS (In-Service Aircraft for a Global Observing System; www.iagos.org). Their observation systems are deployed on a fleet of commercial aircraft and aim at the provision of long-term, regular, and spatially resolved in situ observations of the atmospheric composition on a global scale. The combined water vapour and relative humidity time series spans now more than 27 years and is comprised of nearly 65000 flights. This makes the data set well-suited for long-term characterization of the water vapour distribution in the extratropical UTLS, namely at mid-latitudes with highest flight densities.

 We will present analyses of the time series from 1996 to 2020 for long-term changes of absolute humidity, temperature, relative humidity with respect to ice (RHice) and occurrence of ISSRs. Our focus lies on different altitude levels in the UTLS at northern mid-latitudes over the regions Eastern North America, North Atlantic and Europe.

How to cite: Rohs, S., Smit, H., Blomel, T., Li, Y., Bundke, U., and Petzold, A.: Evaluation of long-term changes of upper tropospheric and lower stratospheric water vapour and ice supersaturated regions in different altitudes and geographical regions derived from MOZAIC and IAGOS routine in-situ observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14733, https://doi.org/10.5194/egusphere-egu23-14733, 2023.

Trace gas measurements are routinely performed using ground-based solar absorption spectroscopy in measurement networks such as NDACC (Network for Detection of Atmospheric Composition Change) and TCCON (Total Carbon Column Observing Network). For water vapour there exist radiosonde measurements providing high vertical resolution but limited temporal resolution. Retrievals from infrared emission spectrometry bridge a temporal gap in the measurement of trace gases during polar night. Measurements are possible dayround under cloud free conditions. At the AWIPEV site in Ny-Ålesund, Svalbard, we deploy a Bruker Vertex 80 FTIR emission spectrometer with a maximum resolution of 0.08 cm⁻¹ which is able to resolve individual spectral lines. We present optimal estimation retrievals of water vapour and methane. The results are compared to daily radiosonde measurements and TCCON retrievals. First results of applying our retrieval to emission spectra with a reduced resolution are also shown. This will in the future allow to include the retrieval on E-AERI-type instruments with their lower resolution deployed e.g. during the MOSAiC campaign.

How to cite: Heizmann, L., Palm, M., Notholt, J., and Buschmann, M.: Trace gas retrievals from infrared emission spectrometry in the Arctic, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13122, https://doi.org/10.5194/egusphere-egu23-13122, 2023.

This paper highlights the main findings of the eighteenth annual Greenhouse Gas Bulletin (https://library.wmo.int/index.php?lvl=notice_display&id=22149) of the World Meteorological Organization (WMO). The results are based on research and observations performed by laboratories contributing to the WMO Global Atmosphere Watch (GAW) Programme (https://community.wmo.int/activity-areas/gaw).

The Bulletin presents global analyses of observational data collected according to GAW recommended practices and submitted to the World Data Center for Greenhouse Gases (WDCGG). Bulletins are prepared by the WMO/GAW Scientific Advisory Group on Greenhouse Gases in collaboration with WDCGG.

Observations used for the global analysis are from more than 100 marine and terrestrial sites worldwide for CO₂ and CH₄ and at a smaller number of sites for other greenhouse gases. The globally averaged surface mole fractions calculated from this in situ network reached new highs in 2021, with CO₂ at 415.7 ± 0.2 ppm, CH₄ at 1908 ± 2 ppb and N₂O at 334.0 ± 0.1 ppb. These values constitute, respectively, 149%, 262% and 124% of pre-industrial (before 1750) levels. The increase in CO₂ from 2020 to 2021 was equal to that observed from 2019 to 2020 and larger than the average annual growth rate over the last decade. For CH₄, the increase from 2020 to 2021 was higher than that observed from 2019 to 2020 and considerably higher than the average annual growth rate over the last decade. For N₂O, the increase from 2020 to 2021 was slightly higher than that observed from 2019 to 2020 and also higher than the average annual growth rate over the last decade.

The Bulletin highlights the exceptional growth of CH₄ in 2020 and 2021. The causes of these exceptional increases are still being investigated though analyses of measurements of atmospheric CH₄ abundance and its stable carbon isotope ratio ¹³C/¹²C indicate that the increase in CH₄ since 2007 is associated mostly with biogenic processes, but the relative contributions of anthropogenic and natural sources to this increase are unclear.

The Bulletin further highlights that the accuracy of emissions estimates from atmospheric measurements depends on the geometry of the surface network, pointing to the large observational gaps in tropical regions and the interior of the Asian continent. The tropics accommodate not only highly uncertain emissions from natural wetlands, but also the atmospheric hydroxyl radical sink of CH₄, which is largest there. Surface measurements provide limited information to distinguish between increasing surface emissions and decreasing atmospheric sinks, which could both explain the increasing atmospheric CH₄ abundance.

WMO is working with the broader greenhouse gas community to develop a framework for sustained, internationally coordinated global greenhouse gas monitoring. These efforts are envisaged to result in an internationally coordinated approach to observing network design and acquisition, international exchange and use of the observations. It is foreseen that this will result in the expansion of the in-situ network, especially in currently undersampled regions and lead to reduced uncertainties in the quantification of the net atmospheric balance of CH₄ and other greenhouse gases.

How to cite: Tarasova, O., Vermeulen, A., Sawa, Y., Houweling, S., and Dlugokencky, E.: The state of greenhouse gases in the atmosphere using global observations through 2021, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15201, https://doi.org/10.5194/egusphere-egu23-15201, 2023.

The continuous population and economy growth demands more energy, currently provided predominantly by burning of fossil fuels. However, the depletion of fossil fuel resources and the detrimental environmental impacts of burning fossil fuels are driving the public opinion and governments towards renewable energy (RE) sources. Solar and wind power are the most promising, but its reliability is shadowed by their weather dependence. Hydrogen is considered as a very promising energy carrier which can overcome the limitations of the existing RE sources. Producing hydrogen at the solar panel fields or incorporating water electrolysers within wind turbines will smooth the energy supply, and even reduce the energy transport. If the hydrogen economy takes effect as anticipated, then the hydrogen impact on the climate needs to be re-assessed. In order to simulate future hydrogen concentrations, it is necessary to build a model which can simulate present day hydrogen emissions and sinks, and resultant atmospheric concentrations, which are currently infrequently measured. Building a history of hydrogen measurements opens up possibilities in the future to determine background and pre-existing hydrogen sources, and gives a baseline before the switch to a hydrogen economy.

Historically, Reduction Gas Analysers (RGA) were the workhorse in the laboratory and field, where reductive gasses like hydrogen or carbon monoxide release mercury gas by passing along a heated solid mercuric oxide bed, which in turn is analysed by ultraviolet (UV) absorption. The method is well established but lacks linear response and stability. CSIRO is working on novel methods for more accurate and precise hydrogen measurement. The Pulsed Discharge Helium Ionization Detector, or simply PDD, is an alternative to the RGA. CSIRO has been operating a PDD for hydrogen at Cape Grim (along with the classic RGA) for 7.5 years using shared calibration tanks. The mean difference between them (50,000+ matched data points, when pollution events are removed) is just 0.02 ppb, proving PDD’s incredible compatibility with the established RGA technique. The PDD also has a demonstrated superior precision and linearity compared to the RGA. Another two PDD systems are operational at Aspendale measuring urban hydrogen since 2019 and 2021. The later one is to be deployed at the CSIRO Clayton site, where Aspendale will relocate to in 2025. Another PDD system is in a development stage, able to measure not just hydrogen, but many other atmospheric gases (CH4, CO2, N2O, Kr, Xe). The inability of optical instruments to measure hydrogen (homonuclear diatomic molecule) will mean that there will be an increased demand for RGA or PDD measurements of hydrogen in the future.

How to cite: Mitrevski, B., Guerette, E.-A., Langenfelds, R., Woodhouse, M., Spenser, D., Krummel, P., and Steele, P.: Measuring Atmospheric Hydrogen Ahead of the Anticipated Hydrogen Economy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16386, https://doi.org/10.5194/egusphere-egu23-16386, 2023.

Measurements of BrO obtained in situ from the NASA ER-2 aircraft and balloons (HALOZ balloon-borne ClO/BrO instrument) between 1987 and 2000 are used to estimate the trend in total inorganic bromine (Bry). Despite the significance of ozone destruction by BrO, due to the analytical difficulty in quantifying very low abundances of bromine radicals present in the stratosphere these were the only direct observations of the dominant species of inorganic bromine that were made often enough over this period to allow for this analysis. In particular, this work focuses on observations in the perturbed polar vortices when BrO chemistry is dominated by reaction with ClO, and thus is less sensitive to systematic errors due to uncertainties in reactions with compounds such as HOx and NOx that dominate at lower latitudes. We use a detailed one-dimensional photochemical model with recommended rate parameters for key chemical processes, initialized with simultaneous observations of ClO and O₃, to determine the atmospheric bromine partitioning under the specific photochemical conditions of each observation. We find that total inorganic bromine increased by ~43% over this time and reaches a value in 2000 that agrees well with the other observations that have since shown a leveling off, and small decrease, of inorganic bromine in the stratosphere since 2000. Within the accuracies of the BrO measurements and modeled partitioning, our results are consistent with a relatively constant value of 4 ppt find for very short-lived bromine substances (VSLSs) over the period of these observations. These results extend the Bry record deduced in recent WMO ozone assessments by 13 years and add further confidence to our understanding of ozone depletion due to bromine compounds over this critical period when inorganic bromine was increasing rapidly due to emissions of anthropogenic compounds, such as Halons and methyl bromide used in fire extinguishers and for fumigating crops.

How to cite: Toso, L. and Toohey, D. W.: The trend in stratospheric bromine from 1987 to 2000 deduced from in situ measurements of BrO in the Winter Polar Vortices, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14464, https://doi.org/10.5194/egusphere-egu23-14464, 2023.

Amount of ozone in the stratosphere is very small as compared to other trace gases in the atmosphere. Yet, significant changes in its concentrations have great consequences in the environment and ecosystems. However, such drastic changes in ozone happens only in the high and middle latitudes, particularly in the polar spring, where chemical ozone loss occurs due to halogen-catalysed chemistry on polar stratospheric clouds. In the tropics, the amount of column ozone is very small and the ozone loss is also very small over the years, as compared to high and mid-latitudes. The ozone analyses in the tropical latitudes show a consistent picture of ozone evolution in the past four decades, as there is no significant loss or increase, although small negative trends are found. Recent studies have demonstrated that these negative trends in the tropical upwelling region are due to the increase in the speed of Brewer-Dobson Circulation, which brings tropospheric ozone to the lower stratosphere. This is clearly pictured in the time series of tropical ozone in recent years. The long-term trend in tropical total column ozone also shows no noticeable difference in recent years from the past decades. No measurements and no analyses show any signature of ozone hole in the tropics and all claims so far made are scientifically not sound and unconvincing. It is very unlikely that we would get an ozone hole outside the polar region.

How to cite: Kuttippurath, J. and Gopikrishnan, G. P.: Is there an Ozone hole in the Tropics?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11273, https://doi.org/10.5194/egusphere-egu23-11273, 2023.

Total ozone is a measure of the protection of the biosphere from UV radiation. Extratropical total ozone recovery trends of about +0.5%/decade are consistent with the continuous decline in stratospheric halogen loading since the middle 1990s as a consequence of the Montreal Protocol and its Amendments on phasing out ODS. Nevertheless, the recovery (or chemistry-related) trends in the northern hemisphere (NH) are compensated by changes in atmospheric dynamics leading to stable ozone levels since about 2000 (apart from year-to-year variability). The near-global (60°S-60°N) average total ozone level is currently about 2-3% below the 1964-1980 mean.

Lower stratospheric ozone, the dominating contributor to the total ozone column and derived from limb satellite observations, shows globally (below 60° latitude) a slightly negative (but mostly statistically insignificant) trend of about -1.5%/decade since 2000, which is not consistent with the stable total ozone levels in the NH.  Some studies suggested that increases in tropospheric ozone compensate for negative lower stratospheric trends leading to stable column levels. The trend regression models applied to ozone profiles and total ozone also differ. For instance, proxies representing changes in atmospheric dynamics and transport have been included for total ozone, but not for ozone profiles, which may also lead to inconsistencies between total and stratospheric column trends.

This presentation will report updated total ozone trends from five merged total ozone datasets up to 2022. The same regression model, including proxies representing atmospheric dynamics and transport, will be then applied to ozone profiles from the merged limb dataset (SAGE II-SCIAMACHY-OMPS) to evaluate the consistency between column and profile trends.

How to cite: Weber, M., Arosio, C., Rozanov, A., Burrows, J. P., Sofieva, V., Coldewey-Egbers, M., Loyola, D., Fioletov, V., Frith, S. M., and Wild, J. D.: Are trends in total ozone consistent with stratospheric ozone trends from satellite observations? Are trends in total ozone consistent with stratospheric ozone trends from satellite observations?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13119, https://doi.org/10.5194/egusphere-egu23-13119, 2023.

Observations in limb geometry from satellite platforms are very valuable for monitoring the stratospheric ozone layer on a global scale, as they provide information with high spatial and temporal coverage and good vertical resolution. At the University of Bremen, ozone profiles were retrieved from observations from two limb sounders, SCIAMACHY (2002-2012) and OMPS-LP (2012-present), using similar retrieval algorithm setups. These two data sets were merged to obtain a consistent time series of longitudinally resolved global ozone distribution, referred to below as SCIA+OMPS. Recently, the OMPS-LP data set has been re-processed by using improved L1 data produced by the NASA team, with the main aim to mitigate the long-term drift affecting the OMPS-LP time series. The results of this re-processing will be presented; the use of the updated data set gives more confidence in the trend studies from the SCIA+OMPS time series.

The overarching aim of this study is the investigation of vertically consistent patterns in the longitude-resolved trends, particularly at northern mid- and high-latitudes above 30 km altitude, detected in the SCIA+OMPS data set. Large positive trends are found over the Atlantic sector, whereas close-to-zero changes are detected over the Siberian/Pacific sector. To investigate the origin of this behaviour, we performed full chemistry simulations of the TOMCAT global 3-D chemistry transport model (CTM), forced by ERA5 reanalysis, for the 2003-2020 period. We then applied a multi-linear regression model including dynamical proxies to both the satellite observations and TOMCAT simulations. First, we compare the trend resulting from the merged data set with those from the model simulations to check the consistency of the detected zonal and longitudinally resolved patterns. Then, seasonally and monthly resolved trends are studied as they provide valuable insight into the observed zonal asymmetry of the trends. We find the largest variability with longitude occurring in winter- and springtime, and a good consistency between observations and the CTM.

By comparing ozone changes, with trends in temperature and meridional wind fields from ERA5, we investigated potential mechanisms driving the observed asymmetry. Dedicated TOMCAT simulations showed the negligible role of photochemical processes for the observed pattern. We therefore consider the behaviour to be mainly dynamically driven. A composite analysis supports the hypothesis that the long-term change in the position of the polar vortex has influenced the winter- and springtime ozone concentrations and has led to the zonal asymmetry identified in the data and model.

How to cite: Arosio, C., Chipperfield, M. P., Rozanov, A., Weber, M., Dhomse, S., Feng, W., and Burrows, J. P.: Investigating zonal asymmetry in stratospheric ozone trends at northern high latitudes using satellite limb observations and CTM simulations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7671, https://doi.org/10.5194/egusphere-egu23-7671, 2023.

The ACE-FTS and MAESTRO instruments have now been operating on the Canadian Space Agency’s SCISAT satellite as the Atmospheric Chemistry Experiment (ACE) for nearly 20 years.  The ACE satellite is approximately 1 m in diameter and 1 m deep and has a mass of 150 kg.  The Measurement of Aerosol in the Stratosphere and Troposphere Retrieved by Occultation (MAESTRO) spectrophotometer continues to measure ozone, water vapour and aerosol in the stratosphere and upper troposphere.  Like the ACE‑FTS, MAESTRO delivers results from nearly 30 occultation measurements per day, but with a higher vertical resolution of just over 1 km over a range as large as 5 to 40 km as meteorological conditions allow.  It measures from 500 nm to 1000 nm with a resolution of 1 to 2 nm.  The instrument design and performance will be briefly discussed and the algorithms developed to process the data and deal with peculiarities in the performance of the satellite will be described. 

Significant progress has been made recently in improving the retrievals that has resulted in improved accuracy and a larger number of successful retrievals at lower altitudes.  A new dataset with these improvements will be available for other researchers.  Some examples which illustrate the improvements will be presented.

The ACE satellite was funded by the Canadian Space Agency (CSA) and launched by NASA. The CSA funds the MAESTRO data processing.  Environment Canada (EC) partly funded the construction of the MAESTRO instrument. 

How to cite: McElroy, C. T., Walker, K. A., Drummond, J. R., Zou, J., and Jeffery, P. S.: The MAESTRO Spectrophotometer on Canada’s SCISAT satellite: Advances in data processing and improved data products, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17382, https://doi.org/10.5194/egusphere-egu23-17382, 2023.

Stratospheric ozone (O3) absorbs biologically harmful solar ultraviolet radiation, mainly in the UV_B and UV_C spectral range. When reaching the surface, such UV radiation poses a well documented hazard to human health. In order to quantify this amount of UV radiation and to make it generally understandable, the World Health Organization has defined an UV Index[1]. It is calculated by weighting the incoming solar irradiance at surface level between 250 and 400 nanometers with their ”harmfulness” to the skin and scaling the results to values that normally range between 1 and 10, surpassing 10 for excessive UV exposure.

Implementing UV Index forecasts in numerical weather prediction (NWP) models allows to alert the public in time if special care for sun protection needs
to be taken. The German Weather Service (DWD) uses its NWP model ICON (ICOsahedral Nonhydrostatic Model)[2] to offer such a forecast for Germany[3]
using external data such as ozone forecasts by the Royal Dutch Weather Service (KNMI) and radiation lookup tables[4].

In our project we extend the capability of ICON to provide a configuration of self-consistent UV Index forecasts that do not require external data. For this, we use ICON-ART[5],[6] with a linearized ozone scheme (LINOZ)[7] and couple the prognostic ozone to the atmospheric radiation scheme Solar-J[8].
Here we present the current state of our UV Index forecast system and compare our results to available reference data.

References:

[1] World Health Organization, World Meteorological Organization, United Nations Environment Programme, and International Commission on Non-
Ionizing Radiation Protection. Global solar uv index : a practical guide,2002.

[2] Günther Zängl et al.. The icon (icosahedral non-hydrostatic) modelling framework of dwd and mpi-m:
Description of the non-hydrostatic dynamical core. Quarterly Journal of the Royal Meteorological Society, 2015.

[3] https://kunden.dwd.de/uvi/index.jsp.

[4] Henning Staiger and Peter Koepke. Uv index forecasting on a global scale. Meteorologische Zeitschrift, 2005.

[5] D. Rieger et al.. Icon–art 1.0 – a new online-coupled model system from the global to regional scale. Geoscientific Model Development, 2015.

[6] J. Schröter et al.. Icon-art 2.1: a flexible tracer framework and its application for composition studies in numerical weather forecasting and climate simulations. Geoscientific Model Development, 2018.

[7] C. A. McLinden et al. Stratospheric ozone in 3-d models: A simple chemistry and the cross-tropopause flux. Journal of Geophysical Research: Atmospheres, 2000

[8] J. Hsu, M. J. Prather et al.. A radiative transfer module for calculating photolysis rates and solar heating in climate models: Solar-j v7.5. Geoscientific Model Development, 2017.

How to cite: Hanft, V., Ruhnke, R., Seifert, A., and Braesicke, P.: Prognostic Ozone For ICON: Enabling UV Forecasts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6135, https://doi.org/10.5194/egusphere-egu23-6135, 2023.

The decade, 2012 to 2021, was the warmest on record, with the global mean near-surface air temperature in the most recent seven years, 2015 to 2021, keeping hitting record high. Europe, with an increase of 1.94 to 2.01 °C in the mean annual temperature since pre-industry level, is warming much faster than the global average (1.11 to 1.14 °C) (https://www.eea.europa.eu/ims/global-and-european-temperatures). Surface warming disrupts upper-air temperature, which will affect the humidity fields in the upper troposphere. Both ambient temperature and relative humidity with respect to ice (RH_ice) are key factors determining the formation and persistence of contrail cirrus clouds, which exert a net warming radiative forcing among aviation emissions (Lee et al., 2009; Lee et al., 2021).

Previous studies have provided insights into the long-term trend and seasonal variability of upper-air temperature and relative humidity using airborne, radiosonde and reanalysis datasets (Petzold et al., 2020; Chen et al., 2015; Philandras et al., 2017; Essa et al., 2022). The variation of RH_ice in relation to the changing upper tropospheric temperature because of surface warming has, however, rarely been investigated.

In this work, we use the temperature and RH_ice measurements over Western Europe from the European research infrastructure IAGOS (In-Service Aircraft for a Global Observing System; www.iagos.org) to study how the upper-air temperature and RH_ice distributions in the warmest seven years have changed seasonally and regionally compared to the IAGOS-MOZAIC period, 1995 to 2010, when the surface warming was not so drastic. We will focus on whether the occurrence frequency of contrail forming regions, i.e., slightly ice subsaturated to supersaturated regions in the upper troposphere, would be affected by the increasing warming climate, which could promote our understanding of contrail mitigation.

[Note: This work is carried out under the frame of EU H2020 Research and Innovation Action “Advancing the Science for Aviation and Climate (ACACIA)”, Grant Agreement No. 875036.]

How to cite: Li, Y., Rohs, S., Krämer, M., and Petzold, A.: Does surface warming over Western Europe affect the occurrence frequency of contrail forming regions?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4629, https://doi.org/10.5194/egusphere-egu23-4629, 2023.