A ROBUST, ACCURATE AND FLEXIBLE CODE FOR COMPUTING NEAR-SURFACE INFRARED RADIATION IN THE ATMOSPHERE

摘要

As radiation plays a key role in the determination of the near-surface thermal environment, great accuracy is required in the computation of radiative fluxes. A small error in the fluxes can lead to large errors in estimating cooling rates. A new code which provides accurate estimates of fluxes and cooling rates near the surface of earth, in different infra-red bands and for arbitrary surface emissivities, is presented here. Unacceptable oscillations were found near the surface in the cooling rates simulated using the code developed by Chou et. al. To overcome this problem we have implemented a new numerical scheme which has proved satisfactory. The present results have shown excellent agreement with ICRCCM test cases. The present radiation code has no restrictions on the number of grid points and yields fluxes accurate to a prescribed tolerance. The computing times are comparable (for given accuracy) to those demanded by current codes in use elsewhere. The code developed is thus accurate, robust and flexible, and can be used with equal ease in computation for General Circulation Models as well as for near-surface applications in agricultural meteorology and remote sensing.