RECONSTRUCTION OF MONTHLY MEAN 700-MB HEIGHTS FROM SURFACE DATA BY REVERSE SPECIFICATION

This paper demonstrates an objective method of computing monthly mean 700-mb height anomalies (H) at 108 grid points in the Western Hemisphe re for a 40-yr period as a function of concurrent anomalies of monthly mean sea level pressure (P), at the same 108 points used for H, and m onthly mean surface air temperature (T) averaged over 112 areas in Nor th America. The authors applied a forward stepwise program to derive l inear multiple regression equations that explained 81% of the variance of H by means of only 3.5 variables, averaged over ail months and gri d points. The stability of these equations held up well on 6 yr of ind ependent data in terms of explained variance, root-mean-square error, and the spatial anomaly correlation coefficient. Therefore, it seems f easible to reconstruct maps of H for the first half of the twentieth c entury as a function of data on P and T only.