Retrieval of Formaldehyde Columns from GOME as Part of the GSE Promote and Comparison with 3d-CTM Calculations
Isabelle De Smedt(1), Michel Van Roozendael(1), Ronald Van der A(2), Henk Eskes(2) and Jean-François Müller(1)
(1) BIRA-IASB, 3 Avenue Circulaire, 1180 Brussels, Belgium
(2) KNMI, P.O.Box 201, 3730AE De Bilt, Netherlands
Formaldehyde (HCHO) is a central component of tropospheric chemistry. It constitutes an important indicator of hydrocarbons emissions in the troposphere. The photodissociation of HCHO also plays a role in the production of CO and NO2. Through quantification of the global abundance of formaldehyde using satellite instruments, one expects to provide new constraints on the emissions of non-methane VOCs (NMVOCs) as well as on the budget of CO, which play a key role in the budget of tropospheric ozone and the hydroxyl radical OH. Formaldehyde is a product of the air quality service of the PROMOTETEMIS project (ESAGMES Service Element Atmosphere) and of the Dragon project “Air quality monitoring and forecasting in China”.
In the present study, global distributions of formaldehyde columns are derived from GOME for the years 1996 to 2001. The retrieval process is based on a slant column fitting using the differential optical absorption spectroscopy technique (DOAS), followed by a conversion to vertical column using appropriate air mass factors (AMFs). For the later step, The TM4 chemistry-transport model provides best-guess profiles of HCHO, based on the latest emission inventories, atmospheric transport, photochemistry, lightning modeling and wet/dry removal processes. We focus on a discussion of the main error sources that affect the retrieval of both HCHO slant and vertical columns.
Comparison with tropospheric chemistry models (IMAGES and TM4) are used to investigate the geophysical consistency of the retrieved columns. Furthermore, GOME HCHO is used to investigate the sensitivity of the global HCHO column distributions to change in anthropogenic, biogenic and pyrogenic NMVOC emissions as well as on potentially uncertain parameters in their degradation mechanisms in the IMAGES model.
Keywords: ESA European
Space Agency - Agence spatiale europeenne,
observation de la terre, earth observation,
satellite remote sensing,
teledetection, geophysique, altimetrie, radar,
chimique atmospherique, geophysics, altimetry, radar,