Large-Scale features of the indian summer monsoon rainfall and their association with some oceanic and atmospheric variables |
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Authors: | K D Prasad S V Singh |
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Institution: | Indian Institute of Propical Meteorology, Pashan, Pune-411008.,Indian Institute of Propical Meteorology, Pashan, Pune-411008. |
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Abstract: | The summer monsoon rainfall totals for 31 meteorological subdivisions of India for the years 1901-1980 are analysed. The analysis
reveals that four leading eigenvectors (EVs) are significant and account for 65% of the total variance.
The spatial pattern of the first EV exhibits in phase fluctuations over almost the whole India. The large coefficients of
this vector can be considered as representative of the conditions of large-scale flood and drought over the country. The second
pattern reveals the fluctuations mostly over the North Indian region (north of 20° latitude) probably in association with
the Western Disturbances. The third pattern indicates fluctuations over the North-West and the North-East India in opposite
phase and the fourth pattern exhibits the characteristic features of fluctuations associated with ’break’. The spectral analysis
of the coefficients of these EVs revealed quasi-periodicities of 2-5 years.
On the basis of examination of the elements of these EVs the country has been divided into seven homogeneous regions. Rainfall
indices of these regions and of the four EVs have been examined for seeking for association with some oceanic and atmospheric
variables. The association is significant for the coefficients of the first EV and for the rainfall indices of central and
South India. Among all the variables examined, Darwin pressure tendencies have the highest association and appear to be of
special significance in prediction of the monsoon rainfall. |
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Keywords: | |
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