Comparison of Numerical Methods for Computing Radiative Temperature Changes in the Atmospheric Boundary Layer

Abstract

Three models, based on methods of Brooks and Elsasser, and on transmission functions of Davis and Viezee, are used to compute the infrared surface flux and the flux divergence in the lower atmosphere. The three models are compared and brief derivations are given. Data from 0'Neill, Nebr., during the summer of 1953 are used in the computation of the incoming and net radiation at the surface and the infrared cooling rates in the lower atmosphere. Observed radiation data at O'Neill were compared with computed results from the three models. The computed cooling rates from the three models are compared with observed temperature changes. The largest surface flux was calculated by the Brooks model and the smallest by the Elsasser model. The computed net radiation, including the solar radiation, was in better agreement with the observed data than was the total flux. The computed cooling rates agree with those of other authors. The cooling rate computed by the Brooks model is smallest of those computed in the day and nearly the same as the values by the other two models at night. The difference between the day and night results are attributable to the omission of carbon dioxide effects by Brooks. The largest cooling rates are shown by the Elsasser model. The distributions with height of the cooling rates are similar for the three methods.