The information is prepared on the basis of data from the information-analytical system RSF, informative part is represented in the author's edition. All rights belong to the authors, the use or reprinting of materials is permitted only with the prior consent of the authors.

Project titleStudy of spatial and temporal variability of tropospheric ozone over Russia by satellite methods

AffiliationFederal State Budgetary Educational Institution of Higher Education "Saint-Petersburg State University",

Research area 07 - EARTH SCIENCES, 07-607 - Chemical processes, trace gases, aerosols

KeywordsTropospheric ozone, greenhouse effect, air pollution, Russian meteorological satellites

Annotation
Tropospheric ozone (TO) is a greenhouse gas and a reactive and toxic pollutant detrimental to human health and ecosystem productivity. The influence of TO on climate is assessed in terms of its radiative forcing (RF), which is determined as a change in the Earth’s energy flux since 1750 due to changes in TO burden. Based on outputs of multiple models, global-average RF of TO is estimated to be +(0.40 ± 0.20) W m-2, which is approximately 10% of the total anthropogenic RF for the entire industrial period. Tropospheric ozone is the third largest (after carbon dioxide and methane) contributor to the total tropospheric RF. The relatively large uncertainty of this estimate is due to uncertainties in the estimate of pre-industrial ozone levels and uncertainties in present-day distribution of TO. In recent years, more attention has been paid to studies of TO distribution, some regions report of the growth of tropospheric ozone levels, some – of its decrease. The Tropospheric Ozone Assessment Report in the frame of IGAC project (http://www.igacproject.org/activities/TOAR), focusing on the present-day distribution and trends of tropospheric ozone relevant to climate and global atmospheric chemistry model evaluation, was published in 2018. It states, among other things, that the largest TO values are observed over territory of Northern Eurasia, however, the detailed analysis of TO distribution over Russia was not included in this report. It is mainly known that RF, including tropospheric ozone’s RF is different for different regions, therefore climate warming occurs with different intensity in different latitudes. In accordance with the climate models estimates, the normalized on 1 DU radiative forcing of TO totals in average +0.05 W m-2 (for clear-sky conditions). Thus, the RF on regional climate can be assessed using the estimates of TO trends. The current Project is aimed at studying the spatial and temporal distribution of TO over Russia, in particular, in polar and subpolar latitudes, mainly by observations of the Russian spectrometer IKFS-2 aboard the Meteor-M satellite No. 2, operating since 2014 as well as by a number of satellite and ground-based instruments and the results of numerical modelling. As a result of the study, a unique product will be created for obtaining information on the ozone content in the troposphere using Russian satellites. Using this product, the spatio-temporal fields of the distribution of TO over Russia will be analyzed, the features of the TO distribution will be investigated, and new climatological data on TO (monthly average, annual average on grids with different spatial resolution) will be derived. These data will be used for determination of TO anomalies over territory of Russia as well as for estimation of TO seasonal cycle, TO trends and for preliminary assessment of TO contribution to regional RF in Russia.

Expected results
In this Project, we plan to fill a gap in the study of spatial and temporal variabilities of tropospheric ozone (TO) over Russia by using both the new data based on measurements of the Russian IKFS-2 instruments on board the Meteor-M No. 2 and Meteor M No. 2-2 satellites and available TO data (for example, from satellite measurements by IASI and TROPOMI instruments). The data derived will be used to assess the radiative forcing (RF) of TO on the climate of Russia and can be used for accounting in various scenarios of climatological models, for assimilating in modern three-dimensional atmospheric models, etc. In the Project, we plan to obtain the following results: 1. For the first time, an original retrieval strategy, algorithms and software for deriving the data on tropospheric ozone from spectral measurements of the IKFS-2 instrument aboard the Russian satellite Meteor-M No. 2 will be developed. This software and retrieval strategy can be used for investigation of spatial and temporal variability of tropospheric ozone as well as for operational processing of measurements of Russian meteorological satellites, which will make it possible to draw up operational maps and track changes in TO in various regions of Russia to assess its radiative forcing (RW) and to study the impact of TO changes on climate on a regional and global scale. 2. For the first time, a massive interpretation of the IKFS-2 spectral measurements will be carried out to obtain the information on TO content over Russia and adjacent regions for the period from 2015 to 2024. The IKFS-2 TO data will be compared with independent satellite and ground-based measurements, their mutual calibration and validation will be carried out, and the accuracy of TO retrieval by various methods will be estimated. This will make it possible to create an archive of TO measurement data with a known accuracy over the territory of Russia (primarily, over its polar and subpolar regions), which can be used both for accounting in three-dimensional models and for analyzing spatial and temporal variations and trends in the content of TO, as well as RF assessments and studies of the impact of TO changes on the climate of various regions of Russia. 3. Using remote sensing data and the results of calculations of three-dimensional numerical models of the atmospheric gas composition (for example, WRF-Chem, EMAC, CAMS reanalysis data), the spatio-temporal distribution of TO over Russia, first of all over Arctic and Subarctic regions, and the factors determining it will be analyzed, in particular, in observed spatio-temporal anomalies in TO content in different regions. New climatological data on TO over these territories will also be obtained, assessments of seasonal variability and TR trends in various regions of Russia will be carried out. These new climatological data and assessments will be used for preliminary calculations of the TO RF for climate on a regional scale, and in the future, they can be used to take into account climatological models in various scenarios and assimilated into modern three-dimensional atmospheric models.

Annotation of the results obtained in 2023
As a result of the first year of the Project, a methodology, algorithms, and software were developed based on the artificial neural networks (ANN) method for deriving the tropospheric ozone columns (TrOC) from the spectra of outgoing thermal radiation measured by the Russian satellite device IKFS-2. The results of IKFS-2 test measurements of TrOC were obtained for 5 different ANNs, trained both on data from satellite measurements of TrOC by the TROPOMI device, and on data from measurements of ozone profiles using ozonesondes of the global measurement network. Estimates of the accuracy of TrOC measurements were obtained based on the analysis of the direct problem and on the analysis of the accuracy of approximation of the ANN results. The uncertainty of IKFS-2 TrOC measurements was estimated as 8–12%. To assess the quality of the developed software, test measurements of TrOC were analyzed and compared with data from independent ground-based measurements of TO using a Bruker IFS 125HR Fourier spectrometer at the St. Petersburg State University site in Peterhof. Both types of data show similar temporal variability—seasonal variation and trend estimates. The standard deviations of the mismatches do not exceed the measurement errors of individual instruments. The retrieval strategy for TrOCs deriving from the measured spectra of solar IR radiation with the Bruker IFS 125HR Fourier spectrometer (FTIR method) using the PROFFIT software used at the stations of the international observation network NDACC was improved and adapted to increase the accuracy and information content of TrOC measurements at the St. Petersburg State University site in Peterhof. Time series of ground-based TrOC measurements were derived for the period from 2009 to 2023. Using the optimized strategy, the errors of FTIR TrOC retrievals do not exceed 7–10%. The temporal variability of TrOC was analyzed and a seasonal cycle was identified with a maximum in the spring, approximately a month after the maximum values of the total ozone content. For the period 2012–2021 a statistically significant decrease in TrOC values in the vicinity of St. Petersburg was obtained, amounting to approximately 6% per decade. The results of ground-based FTIR TrOCs were compared with data from independent satellite TrOC measurements with IASI instruments and joint IASI and GOME-2 measurements (IASI+GOME2). Statistical estimates of the discrepancies were obtained, and recommendations on the use of satellite data for study the spatial and temporal variability of TrOCs were given. Satellite measurements were also analyzed and validated at 2 other NDACC stations – Kiruna (68N) and Izana (28N). An archive of data on the global distribution of TrOCs was created, including regions of Russia and adjacent territories, obtained using various satellite measurements (TROPOMI, IASI, OMI/MLS, IASI+GOME2, etc.) with preliminary estimates of their errors and analysis of comparison of data obtained from various sources. Currently, level 3 TrOC measurements from the TROPOMI satellite instrument exist for the tropical region only. These data were used to train the ANN for solving the inverse problem of deriving the TrOCs from the IKFS-2 spectra. The numerical model for forecasting weather and composition of the troposphere and lower stratosphere with high spatial resolution WRF-Chem was adapted for the St. Petersburg region (for a square measuring 1000 by 1000 km with a center in St. Petersburg), and the results of TrOC modeling were obtained for 4 years (from 2016 until 2019). A database of the TrOC numerical modelling for St. Petersburg and surrounding regions is registered in the database register. The model calculation data were compared with experimental data from ground-based measurements of TrOC and surface ozone concentrations at the St. Petersburg State University site in Peterhof. The correlations between experimental and calculated data for surface ozone concentrations were about 0.5, for TrOCs totaled 0.6–0.7. Test comparisons of the IASI satellite TrOC measurements model calculations were also carried out; estimates of their discrepancy were obtained for different seasons.

Publications

1. Virolainen Y.A., Ionov D.V., Polyakov A.V. Analysis of Long-Term Measurements of Tropospheric Ozone at the St. Petersburg State University Observational Site in Peterhof Izvestiya, Atmospheric and Oceanic Physics, Vol. 59, No. 3, pp. 287–295 (year - 2023) https://doi.org/10.1134/S000143382303009X

2. Virolainen Y.A., Nerobelov G.M., Polyakov A.V. Comparison of Satellite and Ground-Based Measurements of Tropospheric Ozone Columns in the Vicinity of St. Petersburg Izvestiya, Atmospheric and Oceanic Physics, Vol. 59, No. 4, pp. 411–420 (year - 2023) https://doi.org/10.1134/S000143382304014X

3. Virolainen Y.A., Nerobelov G.M., Polyakov A.V., Akishina S.V. Comparison of satellite and groundbased measurements of tropospheric ozone Proc. SPIE 12780, 29th International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics, Vol. 1278, 127804X (year - 2023) https://doi.org/10.1117/12.2688764

4. - «База данных численного моделирования распределения озона в тропосфере Санкт-Петербурга и прилегающих регионов» (TROPOZ) -, Номер регистрации (свидетельства): 2023621780 Дата регистрации: 01.06.2023 (year - )

5. - Ученые: концентрации "вредного" озона над Петербургом уменьшаются РИА Новости, - (year - )

6. - В СПбГУ определили, что концентрации «вредного» озона над Петербургом уменьшаются AK&M, - (year - )

7. - Физики СПбГУ определили, что концентрации «вредного» озона над Петербургом уменьшаются Фотопарацци, - (year - )