Long-term variations of aerosol optical depth according to satellite data and its effects on radiation and temperature in the Moscow megacity

Abstract

The rapid development of large megacities, coupled with emission regulations, can lead to long-term variations in aerosol optical depth over urban area which has an impact on radiation and temperature. This study aims to evaluate the radiation effects of aerosol pollution in Moscow and its surrounding areas using MAIAC data obtained from MODIS satellite data for three distinct periods: 2000–2006, 2007–2014, and 2015–2021. A methodology has been developed to incorporate MCD19A2/MODIS data with some additional information from the AERONET Moscow MSU site into the COSMO non-hydrostatic weather forecast model. The aerosol radiative and temperature effects were estimated for cloudless conditions. The highest aerosol optical depth with an average of 0.18 were observed during the 2007–2014 over the newly developed Moscow territory during the active building construction period. In the most recent period, from 2015 to 2021, the mean AOD decreased to 0.1. This reduction resulted in an increase of net shortwave radiation at the bottom of the atmosphere by 15–20 W/m2 and a slight rise in surface air temperature of 0.08 °C compared to 2007–2014. The parameterizations were proposed for net radiation and air temperature at 2 m as a function of aerosol optical depth and solar zenith angle at low surface albedo.