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.

© 2006 Optical Society of America

Atmospheric transmittance of an absorbing gas. 6. OPTRAN status report and introduction to the NESDIS/NCEP community radiative transfer model

Thomas J. Kleespies, Paul van Delst, Larry M. McMillin, and John Derber
Appl. Opt. 43(15) 3103-3109 (2004)

Alternative to the effective transmittance approach for the calculation of polychromatic transmittances in rapid transmittance models

Xiaozhen Xiong and Larry M. McMillin
Appl. Opt. 44(1) 67-76 (2005)

Atmospheric transmittance of an absorbing gas. 5. Improvements to the optran approach

L. M. McMillin, L. J. Crone, and T. J. Kleespies
Appl. Opt. 34(36) 8396-8399 (1995)

Atmospheric transmittance of an absorbing gas. 4. OPTRAN: a computationally fast and accurate transmittance model for absorbing gases with fixed and with variable mixing ratios at variable viewing angles

L. M. McMillin, L. J. Crone, M. D. Goldberg, and T. J. Kleespies
Appl. Opt. 34(27) 6269-6274 (1995)

Fast transmittance model for satellite sounding

P. J. Rayer
Appl. Opt. 34(31) 7387-7394 (1995)