1 3 DOI 10.1007/s00382-014-2307-1 Clim Dyn Analysis of the daily rainfall events over India using a new long period (1901–2010) high resolution (0.25° × 0.25°) gridded rainfall data set D. S. Pai · Latha Sridhar · M. R. Badwaik · M. Rajeevan Received: 28 March 2014 / Accepted: 16 August 2014 © Springer-Verlag Berlin Heidelberg 2014 trends in the frequency of the various categories of DR events during the total period and its two halves differed from the region to the region. The trend analysis revealed increased disaster potential for instant flooding over SCI and NCI during the recent years due to significant increas- ing trends in the frequency (areal coverage) and intensity of the HR and VHR events during the recent half of the data period. However, there is increased disaster potential over NEI and WC due to the increasing trends in the intensity of the rainfall events. There is strong association between the LPS days and the DR events in both the spatial and tempo- ral scales. In all the four regions, the contributions to the total MR events by the LPS days were nearly equal. On the other hand, there was relatively large regional difference in the number of combined HR and VHR events associated with LPS days particularly that associated with monsoon depression (LPS stronger than monsoon depression) days. The possible reasons for the same have also been discussed. The increasing trend in the monsoon low (low pressure) days post 1970s is the primary reason for the observed sig- nificant increasing trends in the HR and VHR events over SCI and NCI and decreasing trend in HR events over NEI during the recent half (1956–2010). This is in spite of the decreasing trend in the MD days. Keywords Daily rainfall events · Trends in the extreme rainfall events · SW monsoon · Long term trends · Low pressure systems 1 Introduction According to the recent Intergovernmental Panel on Cli- mate Change (IPCC) report (IPCC 2013), the earth’s surface temperatures during the last few decades have Abstract In this study, analysis of the long term clima- tology, variability and trends in the daily rainfall events of ≥5 mm [or daily rainfall (DR) events] during the south- west monsoon season (June–September) over four regions of India; south central India (SCI), north central India (NCI), northeast India (NEI) and west coast (WC) have been presented. For this purpose, a new high spatial reso- lution (0.25° × 0.25°) daily gridded rainfall data set cov- ering 110 years (1901–2010) over the Indian main land has been used. The association of monsoon low pressure systems (LPSs) with the DR events of various intensities has also been examined. Major portion of the rainfall over these regions during the season was received in the form of medium rainfall (≥5–100 mm) or moderate rainfall (MR) events. The mean seasonal cycle of the daily frequency of heavy rainfall (HR) (≥100–150 mm) or HR events and very heavy rainfall (VHR) (≥150 mm) or VHR events over each of the four regions showed peak at different parts of the season. The peak in the mean daily HR and VHR events occurred during middle of July to middle of August over SCI, during late part of June to early part of July over NCI, during middle of June to early July over NEI, and during late June to middle July over WC. Significant long term trends in the frequency and intensity of the DR events were observed in all the four geographical regions. Whereas the intensity of the DR events over all the four regions showed significant positive trends during the second half and the total period, the signs and magnitude of the long term D. S. Pai (*) · L. Sridhar · M. R. Badwaik India Meteorological Department, Pune, India e-mail: sivapai@hotmail.com M. Rajeevan Earth System Science Organization, Ministry of Earth Sciences, New Delhi, India