Atmospheric transmittance of an absorbing gas. 7. Further improvements to the OPTRAN 6 approach

Larry M McMillin; Xiaozhen Xiong; Yong Han; Thomas J Kleespies; Paul Van Delst

doi:10.1364/ao.45.002028

Atmospheric transmittance of an absorbing gas. 7. Further improvements to the OPTRAN 6 approach

Appl Opt. 2006 Mar 20;45(9):2028-34. doi: 10.1364/ao.45.002028.

Authors

Larry M McMillin¹, Xiaozhen Xiong, Yong Han, Thomas J Kleespies, Paul Van Delst

Affiliation

¹ Office of Research and Application, National Environmental Satellite, Data, and Information Service, National Oceanic and Atmospheric Administration, Camp Springs, Maryland 20746, USA. yong.han@noaa.gov

PMID: 16579573
DOI: 10.1364/ao.45.002028

Abstract

We present recent improvements in accuracy to the fast transmittance-calculation procedure, Optical Path Transmittance (OPTRAN), which is used for satellite data assimilation at the National Oceanic and Atmospheric Administration. These improvements are (1) to change the absorber space used for ozone, (2) to add new predictors for each gas, and (3) to treat the water vapor line absorption and water continuum absorption as separate terms. Significant improvements in the accuracy of the OPTRAN algorithm for High-Resolution Infrared Radiation Sounders (HIRS) and the Atmospheric Infrared Sounder (AIRS) are demonstrated. The results that we show here extend a recent paper of Xiong and McMillin (2004) that describes the use of a polychromatic correction term to replace the effective transmittance concept to include additional changes that improve accuracy.