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A study of the empirical functions of the height fields over India and their relation with the rainfall

Prasad, KD and Sikka, DR (1982) A study of the empirical functions of the height fields over India and their relation with the rainfall. Proceedings of the Indian Academy of Sciences - Earth and Planetary Sciences, 91 (3). pp. 167-187.

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The empirical orthogonal functions have been obtained for the individual summer monsoon (June through September) months using the grid point values of monthly 700 mb geopotential heights over Indian region. The data for 21 summer monsoon months for the years 1958 to 1978 have been used in the present computation. The major variance reduction is due to the first three dominant functions accounting over 80 of the total variance in each month. The variance reduction only due to the first function ranges from 45 to 65. The first function has in-pbase oscillation throughout the area indicating that the area under study is homogeneous and the centre of the oscillation lies over northwest India. The amplitudes of the first function also show generally quasipers stence in their sign within a season. The second function has two centres of action over the region of monsoon trough which are in phase. The third function has also two centres oriented in the east-west direction but they are in the opposite phase. Fairly large values of correlation coefficients between the patterns of the different monsoon months suggest that the patterns for these months corresponding to the first and the second functions respectively are quite similar. The patterns for these months also evolve with time in a related way. The spectrum analysis to the time series of amplitudes indicates the presence of the quasi-periodicity of 3 years during these monsoon months. The amplitudes corresponding to the dominant functions are found to be significantly related with the rainfall of central and western parts of India

Item Type: Article
Additional Information: Copyright of this article belongs to Indian academy of Science
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 17 Apr 2015 11:18
Last Modified: 17 Apr 2015 11:18

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