First global distributions of methanol and formic acid retrieved from the IASI/MetOp thermal infrared sounder

Abstract

Methanol (CH<sub>3</sub>OH) and formic acid (HCOOH) are among the most abundant volatile organic compounds present in the atmosphere. Their role in tropospheric chemistry stems from their influence on the oxidizing capacity of the atmosphere and, in the case of HCOOH, from its influence on the acidity of clouds and precipitation. In this work, we derive the first global distributions of these two organic species using 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. Global correlations between methanol and formic acid as well as correlations between these two species and carbon monoxide are also presented and discussed

Spaceborne Measurements of Formic and Acetic Acids: A Global View of the Regional Sources

“…In this framework, continuous and homogeneous global satellite observations may provide information on the nature of the missing sources and more constraints on their atmospheric budget. For instance, the first global distributions of HCOOH (Pommier et al, ; Razavi et al, ) obtained from the nadir‐looking Infrared Atmospheric Sounder Interferometer (IASI) satellite sensors (Clerbaux et al, ) and assimilated by the chemistry‐transport model IMAGES, led to the identification of sizeable missing sources of HCOOH from the tropical and boreal forests (Stavrakou et al, ). The COOH budget remains less constrained since, until now, COOH has only been detected in IASI spectra recorded in exceptionally large fire events (Clarisse et al, ; Coheur et al, ).…”

Dietary Methanol Regulates Human Gene Activity

“…Terrestrial atmospheric MeOH emissions come from volcanoes, H 2 and CO 2 generation within seafloor hydrothermal systems [10] – [12] and biomass combustion. However PME-mediated emissions from plants are most likely the largest source of MeOH in the atmosphere [13] – [15] . MeOH accumulates in a plant's intercellular air space or liquid pool at night when the stomata close, and a large MeOH release can be observed in the morning when the stomata open [8] , [16] , [17] .…”

Les résultats exceptionnels de Iasi, sondeur atmosphérique hyperspectral de Metop

“…(2) GMES : Global Monitoring of Environment and Security. L'acide formique (HCOOH) et le méthanol (CH 3 OH) dégagés par les feux de biomasse peuvent également être mis en évidence et quantif iés (Razavi et al, 2010 ; figure 13).…”