Abstract
Abstract. This work presents observations of a series of short-lived species in biomass burning plumes from the Infrared Atmospheric Sounding Interferometer (IASI), launched onboard the MetOp-A platform in October 2006. The strong fires that have occurred in the Mediterranean Basin – and particularly Greece – in August 2007, and those in Southern Siberia and Eastern Mongolia in the early spring of 2008 are selected to support the analyses. We show that the IASI infrared spectra in these fire plumes contain distinctive signatures of ammonia (NH3), ethene (C2H4), methanol (CH3OH) and formic acid (HCOOH) in the atmospheric window between 800 and 1200 cm−1, with some noticeable differences between the plumes. Peroxyacetyl nitrate (CH3COOONO2, abbreviated as PAN) was also observed with good confidence in some plumes and a tentative assignment of a broadband absorption spectral feature to acetic acid (CH3COOH) is made. For several of these species these are the first reported measurements made from space in nadir geometry. The IASI measurements are analyzed for plume height and concentration distributions of NH3, C2H4 and CH3OH. The Greek fires are studied in greater detail for the days associated with the largest emissions. In addition to providing information on the spatial extent of the plume, the IASI retrievals allow an estimate of the total mass emissions for NH3, C2H4 and CH3OH. Enhancement ratios are calculated for the latter relative to carbon monoxide (CO), giving insight in the chemical processes occurring during the transport, the first day after the emission.
Highlights
Most of the processes driving atmospheric chemistry occur on time scales of seconds to days
This paper concentrates on two large fire events that occurred in the Northern Hemisphere since the Infrared Atmospheric Sounding Interferometer (IASI) launch in October 2006: the August 2007 wildfires in the Mediterranean basin and the April–May 2008 boreal fires in Southern Siberia and Eastern Mongolia, in the vicinity of the Baikal Lake
This would be consistent with the IASI temperature profiles provided by EUMETCast, which shows an inversion layer at about 2.2 km (Fig. 1, right panel), and may give indication, as extensively discussed in Clarisse et al (2009b), of the altitude of the plume at this location, i.e. within or just above the boundary layer
Summary
Most of the processes driving atmospheric chemistry occur on time scales of seconds to days. Ground-based instruments located nearby source regions, such as urban areas, are obviously best suited for measuring reactive species in the boundary layer, as they offer at the same time a high sensitivity (down to a few parts per trillion – 10−12 – in fractional concentration), accuracy and repetitiveness. They are important for the local air quality surveillance and forecast systems. We draw conclusions and open perspectives for further research, notably in regard to the possibility to obtain global distributions for some of the newly species observed
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