Evolution of the National Meteorological Center global data assimilation system: January 1982-December 1983.

Abstract

A number of changes were made to the National Meteorological Center global data assimilation system (GDAS) during 1982 and 1983. The most significant of these changes was the replacement of the quasi-univariate, sigma-coordinate optimum interpolation analysis procedure by a version that performs a fully multivariate analysis on mandatory pressure surfaces. The new analysis technique is described in some detail. -from Authors