GEOPHYSICAL MONOGRAPH SERIES, VOL. 196, PP. 153-168, 2012
Extreme Events and Trends in the Indian Summer Monsoon
The extreme events and trends in low-pressure systems (LPSs), rainfall, and surface air temperature over the Indian monsoon
region are examined in this study using long records of daily data. A review of recent studies on the extreme events over
India is presented, and results from new and extended analyses are also included. The number of days when LPSs exist (or LPS
days) has an increasing trend during 1930–2003. In recent years, the LPS days of depressions have shown a decreasing trend,
while the lows and cyclonic storms have shown increasing trends. The moderate rainfall events over central India (CI) and
Western Ghats have decreased during 1951–2004, while heavy and very heavy rainfall events have increased during this period.
This has resulted in a decreasing trend in the seasonal mean rainfall and an increasing trend in the seasonal variance of
daily rainfall over the two regions. The daily mean surface air temperature and the daily maximum temperature both have increasing
trends in their respective seasonal means over CI during 1969–2005. The very high temperature events of both daily mean and
daily maximum have increasing trends, while the moderate events show decreasing trends.
Citation: Krishnamurthy, V. (2012), Extreme events and trends in the Indian summer monsoon, in Extreme Events and Natural Hazards: The Complexity Perspective, Geophys. Monogr. Ser., vol. 196, edited by