Open AccessA fast radiative transfer model for simulating high‐resolution absorption bands
Author(s) -
Duan Minzheng,
Min Qilong,
Li Jiangnan
Publication year - 2005
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2004jd005590
Subject(s) - radiative transfer , atmospheric radiative transfer codes , radiance , computational physics , scattering , absorption (acoustics) , physics , optics
A fast radiative transfer model has been developed for simulating high‐resolution absorption bands. The first scattering radiance is calculated accurately by using the higher number of layers and streams for all required wave number grids. The multiple‐scattering component is extrapolated and/or interpolated from a finite set of calculations in the space of two integrated gaseous absorption optical depths to the wave number grids: a double‐ k approach. The double‐ k approach substantially reduces the error due to the uncorrelated nature of overlapped absorption lines. More importantly, these finite multiple‐scattering radiances at specific k (λ i ) values are computed with a reduced number of layers and/or streams in the forward radiative transfer model. To simulate an oxygen A‐band spectrum, 28 calculations of radiative transfer are needed to achieve an accuracy of 0.5% for most applications under all‐sky conditions and 1.5% for the most challenging multiple‐layer cloud systems (99% of spectrum below 0.5%). This represents a thousandfold time reduction in the standard forward radiative transfer calculation.