Association of the Indian summer monsoon with the northern hemisphere mid-latitude circulation

✍ Scribed by Kripalani, R. H.; Kulkarni, Ashwini; Singh, S. V.

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 382 KB
• Volume: 17
• Category: Article
• ISSN: 0899-8418
• DOI: 10.1002/(sici)1097-0088(199708)17:10<1055::aid-joc180>3.0.co;2-3

✦ Synopsis

The association between the mid±latitude circulation and rainfall over the Indian region on an intraseasonal time±scale is investigated by considering 11 years (1974±1984) of Northern Hemisphere 500 hPa geopotential heights and rainfall data for the Indian summer monsoon months June through to September. On the basis of extensive correlation analysis between the geopotential heights and rainfall, it is seen that three regions over the mid±latitudes, the Manchurian region, the Algerian region and the Caspian sea region show positive correlation with rainfall over India, with higher values north of 20 N latitude. Lead and lag correlations between the heights at the locations identi®ed above and rainfall over India reveals that some common element of low±frequency variability is in¯uencing the mid±latitude circulation and Indian rainfall. On the interannual scale the connections between the winter±time low±frequency patterns (the Paci®c/North Atlantic, the West Paci®c Oscillation, the North Atlantic Oscillation and the Eurasian) and Indian summer monsoon rainfall (ISMR) are investigated. Only the West Paci®c Oscillation pattern shows a signi®cant relationship with the ISMR. Further, the interannual and the decadal variability is examined by using the Northern Hemisphere zonal index data for the period 1900±1993. Results reveal that the decadal±scale variability of the ISMR and the circulation features of the Northern Hemisphere are connected.