Full Spectrum Correlated-k for Shortwave Atmospheric Radiative Transfer

Pawlak, D.T.(a,b), Clothiaux, E.E.(a), Modest, M.M.(c), and Cole, J.N.S.(a), Department of Meteorology, The Pennsylvania State University (a), Air Force Institute of Technology, Civilian Institutions Graduate Programs Division (b), Department of Mechanical Engineering, The Pennsylvania State University (c)
Fourteenth Atmospheric Radiation Measurement (ARM) Science Team Meeting

Fast and accurate atmospheric radiation heating and cooling rate calculations are important for improving global climate and numerical weather prediction model performance. The radiative transfer calculations in atmospheric models must be fast so that the underlying methods can actually be implemented in the models and the calculations must be accurate so that heating and cooling rate errors do not introduce large errors into the model simulations. At present correlated-k approaches to handling gaseous absorption represent the state-of-the-art, but their efficiencies are limited by the requirement that the radiation sources be constant across relatively narrow spectral bands. In this presentation we will present the results of applying a new approach, called the full spectrum correlated-k approach, to atmospheric broadband shortwave heating rate calculations. As the full spectrum correlated-k approach does not require the radiation source to be constant across the spectrum, this approach produces clear-sky flux and heating rate errors less than 1% and 5%, respectively, using only two spectral bands. The first band extends from 0.24 – 0.68 microns and requires five quadrature points, while the second band extends from 0.68 – 4.60 microns and requires ten quadrature points. Requiring only 15 calculations for relatively accurate broadband shortwave heating rate calculations, the full spectrum correlated-k approach may turn out to be an attractive one for numerical model radiative transfer calculations.

Note: This is the poster abstract presented at the meeting; an extended version was not provided by the author(s).