Diametric changes in trends and patterns of extreme rainfall over India from pre-1950 to post-1950

Abstract

Spatially aggregated extreme rainfall over India shows an increasing trend over the last 50 years of the 20th century, while fine-resolution analysis reveals a spatially nonuniform trend. Analysis of 104 years (1901-2004) extreme precipitation over India at 1° resolution, using Extreme Value Theory, reveals that post-1950 extreme rainfall characteristics (intensity, duration, and frequency) and their trends are significantly different from those of before 1950, with spatial nonuniformity. Majority of the locations in India have post-1950 trends of extremes with a different sign as compared to pre-1950. Further investigations with statistical change point analysis reveal that fraction of grid points having post-1975 changes is maximum. Majority of the urbanized areas have post-1975 change points, while the same is not true for nonurban areas. As urbanization has intensified during 1971-1981 in India, these results indicate the possible impacts of urbanization on extreme rainfall trends and patterns. Key Points Post 1950 extreme trends of Indian Monsoon are different from before 1950 Maximum changes in extremes have occurred after 1975, with urbanization Urbanization does not always result in increase of rainfall everywhere in India ©2013. American Geophysical Union. All Rights Reserved.