Impact of convection over the equatorial trough on summer monsoon activity over India
Abstract:Causes of disruption of rainfall (break in monsoon conditions) over the Indian subcontinent during the monsoon months for the period 1979–1998 are investigated using pentad rainfall data from the Global Precipitation Climatology Project (GPCP). Most (about 73%) of the break in monsoon (BM) events were associated with convective activity (rainfall more than 30 mm/pentad) over the equatorial trough (ET) region. The association between these events and the convective activity over the western (WET) and eastern equatorial trough (EET) regions of the tropical Indian Ocean were further explored. These relationships were tested for different (deficit, normal and excess) monsoon conditions over the Indian subcontinent and the El Niño conditions in the Pacific Ocean. There appears to be a negative and significant correlation between the Central Indian Region (CIR) rainfall and EET during deficit and non‐El Niño years. During deficit and El Niño years (1982 and 1987), both CIR and all India rainfall (AIR) exhibited a negative correlation with WET. In the case of years with no breaks, EET was negatively (positively) correlated during the years 1982 and 1992 (1994 and 1997) with AIR. The convective activity was more intense over EET than WET during prolonged BM and also in a deficit and non‐El Niño year (1979).
Document Type: Research Article
Affiliations: 1: Physical Oceanography Division, National Institute of Oceanography, Dona Paula, Goa 403004, India 2: Deutscher Wetterdienst, Satellite Application Facility on Climate Monitoring, Department of Climate and Environment, PO Box 10 04 65, 63004 Offenbach, Germany
Publication date: November 10, 2005