Long-term variability of aerosol optical thickness in Eastern Europe over 2001–2014 according to the measurements at the Moscow MSU MO AERONET site with additional cloud and NO<sub>2</sub> correction

Abstract

Abstract. The atmospheric aerosol properties were obtained within the framework of the AERONET program at the Moscow State University Meteorological Observatory (Moscow MSU MO) over the 2001-2014 period. The quality data control has revealed the necessity of additional cloud screening and NO 2 correction. The application of additional cloud screening according to hourly visual cloud observations provides a decrease in monthly average aerosol optical thickness (AOT) at 500 nm of up to 0.03 compared with the standard data set. We also show that the additional NO 2 correction of the AERONET version 2 data is needed in large megalopolis, like Moscow, with 12 million residents and NO x emission rates of about 100 kt yr −1 . According to the developed method, we estimated monthly mean NO 2 content, which provides an additional decrease of 0.01 for AOT at 340 nm, and of about 0.015 -for AOT at 380 and 440 nm. The ratios of NO 2 optical thickness to AOT at 380 and 440 nm are about 5-6 % in summer and reach 15-20 % in winter when both factors have similar effects on UV irradiance. Seasonal cycle of AOT at 500 nm is characterized by a noticeable summer and spring maxima, and a minimum in winter conditions, changing from 0.08 in December and January up to 0.3 in August. The application of the additional cloud screening removes a local AOT maximum in February. Statistically significant negative trends in annual AOT for UV and mid-visible spectral range have been obtained both for average and 50 % quantile values. The pronounced negative changes were observed in most months with the rate of about −1-5 % yr −1 and could be attributed to the negative trends in emissions (E) of different aerosol precursors of about 135 Gg yr −2 in E SO x , 54 Gg yr −2 in E NMVOC , and slight negative changes in NO x over the European part of Russia. No significant influence of natural factors on temporal AOT variations has been revealed.

Multiyear Typology of Long-Range Transported Aerosols over Europe

“…The distribution of aerosol types in Europe shows that Smoke (37%) and Continental (25%) aerosol types were identified by NATALI software as the predominant aerosol types in Europe, High AOD values (i.e., 0.3) were observed during summer over the Southeast (Figure 3a). The Northeast cluster was characterized by low AOD values for all seasons (with the exception of winter), which can be explained by cleaner air conditions compared to the other clusters (e.g., Reference [43]). The highest values for AE were observed during summer (i.e., months JJA (June, July, August)) and varied from 1.29 for the Southwest and Northwest clusters to 1.55 for the Southeast cluster.…”

Aerosol and Its Radiative Effects during the Aeroradcity 2018 Moscow Experiment

“…The AERONET aerosol retrievals included aerosol optical depth (AOD) within the spectral range from 340 nm to 1020 nm, Angstrom exponent, fine and coarse aerosol AOD modes at 500nm according to the retrieval method described in (O'Neill et al 2001), single scattering albedo (SSA) and aerosol factor of asymmetry (ASYM) according to Dubovik and King (2000). The measurements of columnar aerosol characteristics were made in clear solar disk conditions using the additional cloudscreening filter described in (Chubarova et al 2016). The data from the latest version 3 with final instrument calibration (level 2) were used for Moscow, and the data from version 3 at level 1.5-for Zvenigorod site, since no final data calibration is still available there.…”

Aral's potential sources of dust for Moscow region

“…As was established by us earlier [7] from the data of measurements in 2004-2017 at the Zvenigorod Scientific Station (ZSS, 36.8° E, 55.7° N) of A.M. Obukhov Institute of Atmospheric Physics, the presence of silicates in samples of surface aerosol with particle sizes of 1-2 μm in the Moscow region is associated with the air mass transport from northwestern Kazakhstan and Aral Region. In Moscow (37.2° E, 55.7° N), the AERONET [8] site has been operating since 2001 [9], so it is interesting to investigate the effect of air transport from northwest Kazakhstan and the Aral Region to the aerosol content in the atmospheric column over the Moscow region.…”