Ground-based spectrometric measurements of vertical distribution and column abundance of NO<formula><inf>2</inf></formula> at Zvenigorod, Russia

Results of measurements of vertical distribution and column abundance of NO₂ at Zvenigorod Research Station of the Institute of Atmospheric Physics since 1990 are presented. Measurements are done during morning and evening twilight at solar zenith angles 84-96 with a zenith-viewing spectrophotometer in spectral range 435-450 nm. A vertical distribution of NO₂ constituted by NO₂ abundances in 5 km thick layers and in the thin near-surface layer is retrieved as a solution of an inverse problem using Chahine method. The column NO₂ abundance is obtained as a sum of layer abundances. Random errors of retrieved NO₂ profiles are estimated with the help of a special statistical method based on randomization of measured slant column abundances. Measurements show that stratospheric NO₂ is a subject to diurnal day-to-day intra-seasonal annual and interannual variations. A linear negative trend in the stratosphere column NO₂ abundance has also been estimated. The NO₂ abundance in the lower troposphere is strongly affected by pollution episodes. Regular variations and statistical characteristics of the NO₂ abundance in the near-surface layer have been determined.