Some aspects of the large scale fluctuations of summer monsoon rainfall over India in relation to fluctuations in the planetary and regional scale circulation parameters
- 170 Downloads
Year-to-year fluctuations of summer monsoon (June–September) rainfall of India are studied in relation to planetary and regional scale features. Anomalous epochs in the monsoon rainfall have been found to coincide with the epochs having anomalous patterns of temperature distribution in the northern hemispheric extratropics as well as with the spells of years having anomalous patterns of sea surface temperature distribution in the equatorial Pacific Ocean (EL-Nino phenomenon).
Relationship between monsoonal rainfall and regional atmospheric circulation features is studied by compositing data of five good and five bad monsoon rainfall years over India. A comparison of the two data sets yields interesting relationships between the anomalous patterns of rainfall on the one hand and atmospheric parameters on the other. On the average parameters of monsoon depressions are more or less the same among the two types of composites. The most important distinguishing feature of good monsoon years is the greater frequency of cyclogenesis (monsoon lows included) on the regional scale which keeps the monsoon trough near its normal position and with concomitant higher cyclonic vorticity in the trough zone contributes to greater seasonal rainfall on the regional scale during good monsoon years.
KeywordsSummer monsoon fluctuations monsoon rainfall regional atmospheric circulation southern oscillation
Unable to display preview. Download preview PDF.
- Blanford H 1882Mem. Indian Met. Dept. 3 1Google Scholar
- Dallas W L 1900Mem. Indian Met. Dept. 12 1Google Scholar
- Dhar O N, Rakhecha P N and Mandal B N 1978Weather 33 196Google Scholar
- Joseph P V 1976Proc. Symp. Tropical Monsoons (Poona: Ind. Inst. of Trop. Meteor.) p. 378Google Scholar
- Keshvamurty R N and Awade S T 1974Indian J. Met. Geophys. Hydrol. 25 257Google Scholar
- Koteswaram P 1960Monsoons of the world India Met. Deptt. p. 105Google Scholar
- Matson M 1977NOAA Tech. Mem. NESS 84 1966Google Scholar
- Mossman R C 1924Mem. Indian Met. Dept. 23 157Google Scholar
- Murakami T 1974Atmospheric response to heat sources during July. UHMET-74-04, Deptt. of Met. Univ. of Hawaii.Google Scholar
- Paul D K and Sikka D R 1975Monsoon sea level pressure field, Sci. Report Ind. Institute of Tropical Meteorology, PoonaGoogle Scholar
- Ramage C S 1969Year Book of ASS of Pacific Coast Geographers 30 41Google Scholar
- Ramage C S 1971Monsoon Meteorology, Int. Geophys., Ser. (New York, London: Academic Press)15, p. 296Google Scholar
- Rao Y P 1976Southwest monsoon, Meteor. Monogr. No. 1, 1976, India Met. Dept. pp. 367Google Scholar
- Rowntree P R 1978 Paper presented at Conference on Meteorology over the Tropical Oceans, London, Aug. 1978Google Scholar
- Sikka D R and Gadgil S 1978Indian Met. J. Hydrol. Geophys. 29 219Google Scholar
- Walker G T 1924Mem. Indian Met. Dept. 24 275Google Scholar