Tropospheric HCHO Observations from Satellites: Retrieval, Validation and Integration in 3D Chemical Transport Models

A contribution to ACCENT-TROPOSAT-2, Task Group 1

Isabelle De Smedt

Belgian Institute for Space Aeronomy (BIRA-IASB),
3, Avenue Circulaire, 1180 Bruxelles, Belgium
Tel: 32-2-373.04.06
Fax: 32-2-374.84.23

Formaldehyde (HCHO) is the most abundant of the carbonyl compounds in the atmosphere. In continental areas, formaldehyde is generated from the oxidation of biogenic hydrocarbons, such as isoprene and terpenes and from the oxidation of anthropogenic hydrocarbons. It is also generated directly from incomplete combustion processes, both from biomass burning and from internal combustion engines. The lifetime of formaldehyde is short. Its oxidation by OH radicals generates HO2 which reacts with NO producing NO2, precursors of tropospheric O3. HCHO is also photodissociated to form HCO, which reacts with oxygen to form CO. As a major source of CO, HCHO plays an important role in the global budget of CO in the natural troposphere. The quantification of the global abundance of formaldehyde using satellite instruments might help better constraining the emissions of non-methane VOCs (NMVOCs) used in current state-of-the-art chemical transport models (CTMs). It might also reduce uncertainties on the budget of CO, which play a key role in controlling the abundance of tropospheric ozone. Finally, formaldehyde is an interesting indicator for biomass burning, rice fields and industrial activities. Large areas of improvements remain in retrieving accurate columns of HCHO, e.g. interferences with ozone absorption and Ring effect should be minimized using more advanced spectral fitting methods and the role of clouds, aerosols and HCHO profile shape on the HCHO air mass factors should be further investigated. In this contribution we will focus on addressing these issues based on measurements from several satellite instruments (GOME, OMI and GOME2). Efforts will be done to assess the homogeneity of the data products derived from these different platforms with the aim to derive consistent long-term series of HCHO observations over the 1996-2010 period. Satellite HCHO columns will be used jointly with MOPITT CO columns to constrain the emissions of CO and the NMVOCs, based on an inverse modelling framework, using the 3D tropospheric CTM IMAGES, developed at BIRA-IASB by Jean-François Müller.

Time Schedule                                                                        2006    2007    2008    2009

GOME-SCIAMACHY retrieval                                                **        **          *          *

OMI – GOME2 retrieval and validation                                    **        **          *          *

Inverse modelling                                                                         *        **        * *         *


Approximate manpower and cost                                          2006    2007    2008    2009

Personnel/man-years                                                                 0.5       1          1          0.5

Yearly cost (k€)                                                                       23        48        50        25


Likely funding agencies

ESA, EU, Belgian Science Policy



Michel Van Roozendael, Jean-François Muller (BIRA-IASB),

Ronald Van der A, Henk Eskes (KNMI).



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