Investigating the Impact of the Economic Recession Over Mediterranean Urban Regions on Satellite-Based Formaldehyde Columns; Comparison with Chemistry Transport Model Results

Formaldehyde (CH2O) is an important indicator of tropospheric hydrocarbon emissions and photochemical activity. CH2O is a high-yield intermediate product from the oxidation of Non-Methane Volatile Organic Compounds (NMVOCs) emitted by anthropogenic, biogenic, and biomass burning activities. For the past 30 years CH2O can be measured from space in the near-UV by solar backscatter instruments. An increased trend in CH2O over big cities around the Mediterranean has been observed from space since the beginning of the financial crisis. This fact could be associated with the enhanced use of wood and pellets for domestic/central heating during cold days, diesel being over-taxed and hence too expensive. This change on the fuel type, apart from more frequent PM10 episodes, is also reflected in CH2O emissions. We use satellite measurements to study the temporal variability of the winter-months CH2O column in order to ascertain the increased biomass burning emissions in urban areas which contribute to elevated levels of smog. We also validate the satellite retrievals using a chemistry transport model and test the ability of observations to reproduce geographical and seasonal variability in CH2O emissions over the Southern Europe.