Trend of standardized precipitation index during Indian summer monsoon season in agroclimatic zones of India

Abstract

Abstract. Standardized precipitation index (SPI) was computed with CRU TS3.0 gridded 0.5 × 0.5° monthly precipitation dataset for each of the 14 mainland agroclimatic zones (ACZs) of India for individual months (June, July, August and September) and season (JJAS) of summer monsoon for 56 yr (1951–2006). Mann Kendall Trend Test with the representative SPI of the ACZs shows that only six out of 14 mainland ACZs have a significant trend during summer monsoon. Trans-Gangetic plain significantly gains wetness during the month of June. West coast plain and hill has a typical feature of significant increasing trend of wetness during June and increasing dryness during July. In general Upper Gangetic plain, Middle Gangetic plain, Central plateau and hill and Eastern plateau and hill have a significantly increasing drying trend during the whole duration of summer monsoon season.