Global distribution and variability of formic acid as observed by MIPAS‐ENVISAT

Abstract

Formic acid (HCOOH) vertical profiles have been retrieved from MIPAS‐ENVISAT satellite data in the upper troposphere for the first time. Based on new spectroscopic line‐strength measurements by Vander Auwera et al. (2007) of HCOOH, a retrieval setup was developed and optimized to study its global distribution between 2002 and 2008. A strong seasonality, directly associated to plant growth and corresponding biogenic emissions, is observed and dominates in the middle latitudes of the Northern Hemisphere. Here, the mean monthly volume mixing ratios (VMR) at 8 km altitude typically reach 100–110 parts per trillion in volume (pptv) during the summer and decrease to about 45 pptv in the early winter. At 16 km and higher altitudes, the VMRs remain under the 20 pptv level and have a much smaller amplitude (<10 pptv). In the Southern Hemisphere, strong signals (up to 1 ppbv at 10 km in a single measurement) are detected from biomass burning during the August–October time period and can enhance the monthly mean background levels above specific tropical and midlatitudinal regions by a factor of 2 or more. In‐plume production of HCOOH through photochemical processes has been identified during an extreme event in September 2006, although it is not likely to contribute significantly to the overall upper tropospheric abundances of formic acid.

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

“…Recent work performed with ACE-FTS on quasi-global observations of HCOOH reported an average mixing ratio of about 0.3 ppbv in the free troposphere with hot spots of up to 0.59 ppbv in tropical regions (Abad et al, 2009). Very recent global distributions were also assessed by the MIPAS sounder (Grutter et al, 2010) over a 6 years period. They report seasonal variations that may be associated to biogenic emissions with higher mixing ratios at 8 km during summer (about 100 pptv) than in winter (about 45 pptv).…”

“…Razavi et al: CH 3 OH and HCOOH observations with IASI 2007;Abad et al, 2009). Similarly the observations of the MIPAS limb emission sounder have enabled mapping upper tropospheric distributions of several organic species such as PAN (Glatthor et al, 2007;, acetone as well as HCN and C 2 H 6 (Glatthor et al, 2009); very recently global distributions of formic acid have also been gathered and analyzed (Grutter et al, 2010). The possibility of probing these VOCs lower in the atmosphere using nadir infrared sounders was suggested based on local observations, both by TES (Beer et al, 2008) and IASI , in the latter case in large biomass burning plumes.…”

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

“…The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) limb emission instrument mapped upper-tropospheric distributions of several species, such as HCN and C 2 H 6 (Glatthor et al, 2009). It also measured HCOOH at a 10 km altitude between 70 and 90 • N (Grutter et al, 2010). The Atmospheric Chemistry Experiment (ACE) is able to monitor all seven species derived in this study, with periodic sampling over the Arctic.…”

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)

“…The limb-viewing Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) observed formic acid in young and aged biomass burning plumes in the upper troposphere and derived emission ratios for formic acid to CO [30,31]. 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].…”