Objective Computation of Some Meteorological Quantities

Abstract

This paper describes research in formulating objective weather analysis and forecasting aids for calculation by an electronic computer. Methods based upon single-station techniques for analysis of rawinsoundings are presented for computing wind shear, lapse rate, thermal advection and a parcel stability index. These quantities are useful in identifying phenomena such as fronts, troughs, the tropopause and the level of maximum wind. Average values of height, temperature, humidity and wind components are computed in six arbitrarily defined layers for purposes of representing the gross atmospheric structure. A simple computer technique for calculating kinematical values of horizontal divergence, vorticity, deformation, vertical motion and geostrophic departures from layer-averaged wind and height data at three stations is developed and demonstrated for an area comprised of the midwestern United States. For this region, the computations require only 20 min on a computer of modest speed; therefore, the magnitude of the calculations is no longer an obstacle to their routine application. Limitations of the methods are described. Our experience indicates that these computer routines are adaptable to several operational and research problems even though the multiple-station computations are subject to considerable noise. Further developments of objective techniques and possible means of suppressing noise are described.