Lidar Observations of Stratospheric Aerosols in Obninsk in 2012–2021: Influence of Volcanic Eruptions and Biomass Burning

Abstract

Results of lidar observations at a wavelength of 532 nm in Obninsk over the period from 2012 to 2021 are presented. In 2014–2018 the stratosphere aerosol was in a state close to the background. In 2019, aerosol maxima were observed in the 15–30 km layer associated with the eruptions of the Ambae and Raikoke volcanoes. The seasonal behavior of the integral backscattering coefficient in the background period is presented. In the lower layer of the stratosphere of 13–23 km, an increase in backscattering was observed in the second half of the year, associated with an increase in the number of natural fires. In the 23–30 km layer, the maximum backscattering was observed in summer. It was found that the contribution of the lower layer of 10–15 km to the optical thickness of the entire layer of 10–30 km is on average 61%. This implies the need to take into account the aerosol of the lower layer of 10–15 km in the overall balance of stratospheric aerosol in chemical–climatic models of the stratosphere. In the second half of the year, aerosol of natural fires is often observed in the 10–15 km layer. In some episodes, the addition of natural fire aerosol to an optical layer thickness of 10–30 km with respect to the spherical sulfuric acid aerosol ranges from 50 to 150%. At the same time, in annual mean terms, this additive in 2014–2021 on average was only 10%. In the last 5 years, there has been a trend towards an increase in the content of aerosol from natural fires, but so far the content of sulfate aerosol in the stratosphere remains predominant.