Measurements of formaldehyde total content in troposphere using DOAS technique in Moscow Region: preliminary results of three year observations

Abstract

Measurements of the formaldehyde (HCHO) atmospheric column are performed at Zvenigorod Scientific Station, Moscow Region, Russia since 2008 by the MAX-DOAS instrument. A previously developed algorithm for the formaldehyde retrieval was updated by adding an availability to use information on the surface albedo and the height of the atmospheric boundary layer provided by other measurements and/or modeling. We present preliminary results of the analysis of observations performed in 2010-2012. The obtained data allow quantifying the Moscow megapolis influence on air quality at Zvenigorod. The average HCHO vertical column density observed at the east winds is larger than one at the west winds. The Moscow influence causes the difference of about 0.85×1016 mol cm-2 between these values. This difference slightly depends on the air temperature and the season. A temperature effect is noticeable in the formaldehyde atmospheric column. Our data show statistically significant positive temperature effect in formaldehyde for the background and polluted conditions for temperatures from –5°C to +35°C. The temperature trend in formaldehyde data at Zvenigorod varies between 7.5×10¹⁴ and 9.3×10¹⁴ mol cm^-2 °C^-1 for all wind directions. The increase of the formaldehyde atmospheric column with the increase of the air temperature can be caused by the HCHO formation from non-methane biogenic volatile organic compounds (mainly - isoprene) for which more emission is expected at higher temperatures, and by growth of areas of forest and turf fires.