A new insight on tropospheric methane in the Tropics – first year from IASI hyperspectral infrared observations

C. Crevoisier, D. Nobileau, A. M. Fiore, R. Armante, A. Chédin, N. A. Scott
2009 Atmospheric Chemistry and Physics Discussions  
Simultaneous observations from the Infrared Atmospheric Sounding Interferometer (IASI) and from the Advanced Microwave Sounding Unit (AMSU), launched together onboard the European MetOp platform in October 2006, are used to retrieve a midto-upper tropospheric content of methane (CH 4 ) in clear-sky conditions, in the Tropics, 5 over sea, for the first 16 months of operation of MetOp (July 2007-October 2008. With its very high spectral resolution, IASI provides nine channels in the 7.7 µm band
more » ... ghly sensitive to CH 4 with reduced sensitivities to other atmospheric variables. These channels, sensitive to both CH 4 and temperature, are used in conjunction with AMSU channels, only sensitive to temperature, to decorrelate both signals through a non-linear 10 6856 Abstract ACPD 9, 6855-6887Abstract 20 (IFOV) has a ground resolution of 12 km at nadir. Also flying onboard MetOp, the Advanced Microwave Sounding Unit (AMSU) is a cross-track scanning total-power radiometer with 15 channels that measure scene radiance in the microwave spectrum from 23.8 to 89.0 GHz. The AMSU instrument has an IFOV of 48 km at nadir, with scan range of ±48.3 • from nadir with a total of 30 Earth 25 fields-of-view per scan line. The swath width is approximately 2000 km. 6859 ACPD 9, 6855-6887Abstract ACPD 9, 6855-6887Abstract 20 6861 Abstract ACPD 9, 6855-6887Abstract ACPD 9, 6855-6887Abstract 9, 6855-6887Abstract 25 6869 ACPD 9, 6855-6887Abstract 9, 6855-6887Abstract ACPD 9, 6855-6887Abstract 9, 6855-6887
doi:10.5194/acpd-9-6855-2009 fatcat:4mjsyvglufakzbhjsj4u4pa46m