PCGRIDDS-based isentropic analysis as a forecasting tool in the South African Weather Bureau

Abstract

The principles of isentropic analysis were introduced in the late 1930s, thus it is not a new concept. Although isentropic methods were used in the United States thereafter, they were abandoned due to several practical reasons that will be discussed in this paper. A revival of isentropic analysis took place in the 1970s due to certain corrections being made as well as the availability of computers to do the required conversion to isentropic co-ordinates in short periods of time. The main advantage of isentropic analysis is that it offers the ability to look at atmospheric motion in the way it actually happens - i.e., in three dimensions - due to the fact that isentropic surfaces follow the true motion of a parcel. This concept is especially important when moisture transport is evaluated since the “vertical” motion of the moisture is included in the graphical depiction on isentropic levels. Isentropic analysis of model output data is not meant as a substitute for isobaric analysis, but to complement it by offering a different and unique way to look at the data.

Authors

Categories