Indian Summer Monsoon

One of the most important yet least understood variability in the Indian Summer Monsoon (ISM) is the Intraseasonal Variability (ISV). Characterised by the occurrence of active and break periods, ISV can lead to extensive dry and wet spells as recently evident in the drought of July 2002 and flooding in July 2005. Whereas droughts result in a reduced agricultural output, famine and a reduced economic growth rate, flooding causes loss of life and property. The climatology of ISM and the ISV are examined using two observed datasets, viz. a gridded All India Daily Rainfall (AIDRF) dataset for a 105-year period prepared by the Indian Met Deparatment (IMD) and a 26-year Merged Analysis of Precipitation (CMAP) provided by Climate Predication Centre (CDC). Using two versions of U.K Met office (UKMO) Hadley centre model (HadCM3), the mean monsoon variability and ISV are simulated. The first, without heat flux adjustments (HFA) is the standard model. The second, with HFA compensates for bias in equatorial Indo-Pacific Sea Surface Temperatures (SSTs). ISM under global warming scenario is examined under the umbrella of Intergovernmental Panel of Climate Change (IPCC) assessment reports.