Midtropospheric CO2 concentration retrieval from AIRS observations in the tropics

[1] Midtropospheric carbon dioxide (CO2) concentration is retrieved in the tropics [20S:20N], over sea, at night, for the period April to October 2003 from the Atmospheric Infrared Sounder (AIRS) observations. The method relies on a non-linear regression inference scheme using neural networks. A rough estimate of the mean precision of the method is about 2.5 ppmv (0.7%). The retrieved seasonal cycle and its latitudinal dependence agree well with aircraft CO2 in situ measurements made at the same altitude range. Maps produced on a monthly basis at a resolution of 15° × 15°, although not yet fully understood, show good agreement with known characteristics of CO2 distribution reflecting both atmospheric transport and surface fluxes (fossil fuel emissions, biomass burning, air-surface gas exchanges).

[1]  Geoffrey E. Hinton,et al.  Learning internal representations by error propagation , 1986 .

[2]  Alain Chedin,et al.  A Neural Network Approach for a Fast and Accurate Computation of a Longwave Radiative Budget , 1998 .

[3]  A. Chédin,et al.  Multichannel Radiometric Determination of Sea Surface Temperature: Parameterization of the Atmospheric Correction. , 1981 .

[4]  Mid-tropospheric CO 2 retrieval in the tropical zone from AIRS observations , 2003 .

[5]  Hidekazu Matsueda,et al.  Aircraft observation of carbon dioxide at 8–13 km altitude over the western Pacific from 1993 to 1999 , 2002 .

[6]  A. Hollingsworth,et al.  Annual and seasonal variations of atmospheric CO2, N2O and CO concentrations retrieved from NOAA/TOVS satellite observations , 2002 .

[7]  A. Chédin,et al.  AIRS channel selection for CO2 and other trace‐gas retrievals , 2003 .

[8]  J. Houghton,et al.  Climate change 2001 : the scientific basis , 2001 .

[9]  I. Fung,et al.  Observational Contrains on the Global Atmospheric Co2 Budget , 1990, Science.

[10]  Shuji Kawakami,et al.  Vertical and meridional distributions of the atmospheric CO2 mixing ratio between northern midlatitudes and southern subtropics , 2002 .

[11]  G. W. Sachse,et al.  Airborne observations of the tropospheric CO2 distribution and its controlling factors over the South Pacific Basin , 1999 .

[12]  P. Rayner,et al.  The utility of remotely sensed CO2 concentration data in surface source inversions , 2001 .

[13]  Lihang Zhou,et al.  AIRS near-real-time products and algorithms in support of operational numerical weather prediction , 2003, IEEE Trans. Geosci. Remote. Sens..

[14]  A. Chédin,et al.  First global measurement of midtropospheric CO2 from NOAA polar satellites: Tropical zone , 2003 .

[15]  A. Chedin,et al.  A Fast Line-by-Line Method for Atmospheric Absorption Computations: The Automatized Atmospheric Absorption Atlas , 1981 .

[16]  A. Chedin,et al.  The Improved Initialization Inversion Method: A High Resolution Physical Method for Temperature Retrievals from Satellites of the TIROS-N Series. , 1985 .