Empirical orthogonal analysis of 700 mb geopotentials during the summer monsoon over Asia

Abstract

Mean monthly 700 mb geopotential anomaly fields over the Asiatic region for the four summer monsoon months June to September based on 15 years data (1964 to 1978) have been analysed through an empirical orthogonal functions technique. The analysis shows that the first five dominant functions explain about 80 per cent of the total original variance, thereby affording a method by which 93 per cent of the data reduction is possible in each of the months considered. Correlations have been derived for the first three dominant functions of a month with the corresponding functions of the other months. Similarly, the time amplitudes of the first three functions of a month have been correlated with the corresponding time amplitudes of the other three months. The correlation analyses show that the first function and its associated amplitude for June are significantly correlated with the corresponding functions and amplitudes of the other three months. The time amplitudes of the first and the second functions have been used to determine analogous mean monthly anomaly patterns among different years of the data under study.