[1] Changes in indices of climate extremes are studied on the basis of daily series of temperature and precipitation observations from 116 meteorological stations in central and south Asia. Averaged over all stations, the indices of temperature extremes indicate warming of both the cold tail and the warm tail of the distributions of daily minimum and maximum temperature between 1961 and 2000. For precipitation, most regional indices of wet extremes show little change in this period as a result of low spatial trend coherence with mixed positive and negative station trends. Relative to the changes in the total amounts, there is a slight indication of disproportionate changes in the precipitation extremes. Stations with near-complete data for the longer period of 1901-2000 suggest that the recent trends in extremes of minimum temperature are consistent with long-term trends, whereas the recent trends in extremes of maximum temperature are part of multidecadal climate variability.

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Agriculture (arguably the backbone of India's economy) is highly dependent on the spatial and temporal distribution of monsoon rainfall. This paper presents an analysis of crop-climate relationships for India, using historic production statistics for major crops (rice, wheat, sorghum, groundnut and sugarcane) and for aggregate food grain, cereal, pulses and oilseed production. Correlation analysis provides an indication of the influence of monsoon rainfall and some of its potential predictors (Pacific and Indian Ocean sea-surface temperatures, Darwin sea-level pressure) on crop production. All-India annual total production (except sorghum and sugarcane), and production in the monsoon (except sorghum) and post-monsoon seasons (except rice and sorghum) were significantly correlated to all-India summer monsoon rainfall. Monsoon season crops (except sorghum) were strongly associated with the three potential monsoon predictors. Results using state-level crop production statistics and subdivisional monsoon rainfall were generally consistent with the all-India results, but demonstrated some surprising spatial variations. Whereas the impact of subdivisional monsoon rainfall is strong in most of the country, the influence of concurrent predictors related to El Niño-southern oscillation and the Indian Ocean sea-surface temperatures at a long lead time seem greatest in the western to central peninsula.

Hourly rainfall data recorded at 72 Self Recording Raingauge Stations (SRRG) for the period 1969-2006 are utilized to study the characteristic features of hourly rainfall and diurnal variations of rainfall in India. Temporal changes in the short duration (less than 12 h) rainfall extremes are examined. Time distribution of a heavy rain spell of 24 h duration, which is an important component in water resources management and flood control studies, is analysed. Different aspects of hourly rainfall such as, average number of rain hours in a year, empirical probability distribution functions have also been examined. Analysis indicates, many stations in India have recorded more than 10 cm of rainfall in an hour's duration. Such stations are located along the west coast, foothills of Himalayas and along the tracks of monsoon disturbances. Extreme rainfall events of various duration (3-12 h) show increasing trends, significant at 5% level, at many stations located in central India and peninsular India except for southern part of west coast. Time distribution of hourly rainfall shows that, on average, 25% of the daily rainfall can be received in just 3 h, while 80% can occur in 12 h during the heavy rain spells of 24-h duration.

Temporal changes in the extreme rainfall and temperature characteristics of major river basins on a daily time scale are examined using high-resolution gridded daily rainfall and temperature data sets. Trend analysis is carried out to examine the temporal changes in the frequency, area covered and intensity of the extreme rainfall and temperature events. Rainfall of 10 cm during southwest monsoon season (JJAS), maximum temperature of 40 ∘ C during summer season (MAM) and minimum temperature of 10 ∘ C during the winter season (DJF) have been used as the thresholds to define the extreme weather events of rainfall and temperature data in these river basins. Analysis indicates that during monsoon season zero rainfall days are increasing in all the river basins except some parts of the Krishna and Peninsular river basins. River basins located in the central parts of India show significant increase in the area covered by the heavy rainfall episodes and their intensity. Substantial rise in the monthly maximum temperatures is seen in the Krishna, Peninsular and West Coast river basins. Frequency, area coverage and intensity of hot days during summer season are increasing significantly in the Krishna and Peninsular river basins, while no substantial change has been observed for cold days during winter season in any river basins of the study.