Space-borne Observation of CH4 using IASI and AIRS at NOAA
Abstract
Space-borne observations of methane (CH4) have been carried out at NOAA/NESDIS/STAR using the Atmospheric Infrared Sounder (AIRS) on the EOS/Aqua platform since 2003 and the Infrared Atmospheric Sounding Interferometer (IASI) since 2008. Comparison of the CH4 retrievals from these two different thermal infrared sounders, as well as some results about the mid-upper tropospheric CH4 (MUT- CH4) based on the AIRS and IASI observations and validation in the past several years will be presented. Some discussion on the capability to use AIRS to measure CH4 in the regions where the methane clathrate destabilization was reported, such as e tundra regions on land and continental shelf regions off-shore. Overall, the most sensitivity of AIRS and IASI to atmospheric CH4 is in the mid-upper troposphere with the degree of freedom of ~1.0, and is capable of detecting a less than 2% change of atmospheric CH4 in the tropics and mid latitude regions, but its capability deteriorates to about 2% or more in the polar regions. The seasonal cycle of MUT- CH4 from AIRS and IASI is different from the CH4 in the boundary layer due to the impact of transport, particularly the convection in the summer which leads to the increase of CH4 in early summer. From 7-8 years’s observation of MUT- CH4 from AIRS, we also found recent increase of MUT-CH4 as reported in the ground-based measurement, but the time of the most significant CH4 increase in MUT delays in about 1 year than on the surface, and the increase rate is 30-40% lower. These results support that the increase of surface emission could be the main driver for recent CH4 increase since 2007 as some time is required for CH4 to transport over the globe.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMGC43D0995X
- Keywords:
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- 0365 ATMOSPHERIC COMPOSITION AND STRUCTURE / Troposphere: composition and chemistry;
- 0428 BIOGEOSCIENCES / Carbon cycling;
- 0480 BIOGEOSCIENCES / Remote sensing;
- 1610 GLOBAL CHANGE / Atmosphere