High resolution daily gridded rainfall data for the Indian region: analysis of break and active monsoon spells

Abstract

Here, we report the development of a high resolution (1° x 1° lat./long.) gridded daily rainfall dataset for the Indian region. There are only 1803 stations with mini¬mum 90% data availability during the analysis period (1951-2003). For the analysis, we have followed the in¬terpolation method proposed by Shepard. Standard quality-controls were performed before carrying out the interpolation analysis. Comparison with similar global gridded rainfall datasets revealed that the pre¬sent rainfall analysis is better in accurate representation of spatial rainfall variation. Using this gridded rainfall dataset, an analysis was made to identify the break and active periods during the southwest monsoon season (June–September). Break (active) periods during the monsoon season were iden¬tified as those in which the standardized daily rainfall anomaly averaged over Central India (21-27°N, 72¬85°E) is less than –1.0 (more than 1.0). The break peri¬ods thus identified for the period 1951-2003 were comparable with those identified by earlier studies. Contrary to a recent study, no evidence was found for any statistically significant trends in the number of break or active days during the period 1951-2003. This gridded rainfall dataset is available for non¬commercial applications.