Global distributions of methanol and formic acid retrieved for the first time from the IASI/MetOp thermal infrared sounder

Abstract

Abstract. Methanol (CH 3 OH) and formic acid (HCOOH) are among the most abundant volatile organic compounds present in the atmosphere. In this work, we derive the global distributions of these two organic species using for the first time the Infrared Atmospheric Sounding Interferometer (IASI) launched onboard the MetOp-A satellite in 2006. This paper describes the method used and provides a first critical analysis of the retrieved products. The retrieval process follows a two-step approach in which global distributions are first obtained on the basis of a simple radiance indexing (transformed into brightness temperatures), and then mapped onto column abundances using suitable conversion factors. For methanol, the factors were calculated using a complete retrieval approach in selected regions. In the case of formic acid, a different approach, which uses a set of forward simulations for representative atmospheres, has been used. In both cases, the main error sources are carefully determined: the average relative error on the column for both species is estimated to be about 50%, increasing to about 100% for the least favorable conditions. The distributions for the year 2009 are discussed in terms of seasonality and source identification. Time series comparing methanol, formic acid and carbon monoxide in different regions are also presented.

Five years of CO, HCN, C<sub>2</sub>H<sub>6</sub>, C<sub>2</sub>H<sub>2</sub>, CH<sub>3</sub>OH, HCOOH and H<sub>2</sub>CO total columns measured in the Canadian high Arctic

“…Sources include plant growth, ocean and decomposition of plant matter as well as biomass burning emission Andreae and Merlet, 2001). The principal sink of CH 3 OH is chemical loss due to OH reaction (Heikes et al, 2002) leading to the formation of CO and H 2 CO (Millet et al, 2006;Rinsland et al, 2009;Stavrakou et al, 2011). The lifetime of CH 3 OH in the surface boundary layer is three to six days (Heikes et al, 2002) and between five and ten days on a global scale (Jacob et al, 2005;Stavrakou et al, 2011).…”

Antarctic ozone hole as observed by IASI/MetOp for 2008–2010

“…Due to its large spatial coverage, combined with its low radiometric noise IASI provides twice daily global measurements of key atmospheric species enabling the analysis of species concentrations, global distribution and transport such as O 3 HNO 3 (Wespes et al, 2009). Other reactive species which are retrieved include carbon monoxide (CO) Pommier et al, 2010), methane (CH 4 ) , sulphur dioxide (SO 2 ) (Clarisse et al, 2008), ammonia (NH 3 ) , methanol (CH 3 OH) and formic acid (HCOOH) Razavi et al, 2011). For a full detailed overview of the IASI instrument, its specifications and trace gas species that can be retrieved see Clerbaux et al (2009).…”

Emission Ratios for Ammonia and Formic Acid and Observations of Peroxy Acetyl Nitrate (PAN) and Ethylene in Biomass Burning Smoke as Seen by the Tropospheric Emission Spectrometer (TES)

“…Similarly, Grutter et al used the limb-viewing Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) to retrieve global distributions of formic acid in the upper troposphere and stratosphere [32]. Razavi et al presented global distributions of formic acid retrieved using the nadir-viewing IASI instrument and showed that the retrieved formic acid is correlated with CO during the burning season in Brazil, the Congo, and Southeast Asia [33].…”