A research group of Noah Diffenbaugh and Deepti Singh of the Stanford Woods Institute for the Environment, Bala Rajaratnam, assistant professor of statistics and environmental earth system science has revealed changes in rainfall pattern during Monsoon in India in recent decades. These changes could have major implications on agriculture and water resource management in the country.
The researchers have compared peak monsoon rainfall patterns during two time periods: from 1951 to 1980, and from 1981 to 2011. The team looked specifically at rainfall during the months of July and August, which is the peak of the Southwest monsoon in India. The analysis focused on central India, which is the core of the monsoon region and has extremely high population densities. Here are some facts from the study:
Increase in frequency of extreme wet and dry spells during Monsoon in India
The study reveals that the intensity of extremely wet spells and the number of extremely dry spells during the South Asian monsoon season have both been increasing in recent decades.
Increase in intensity of wet spells and dry spells
The paper reveals that the intensity of rainfall during wet spells between 1981-2011 was significantly higher than 1950-1980. At the same time, dry spells had become 27 per cent more frequent during the latter period, which had twice as many years with three or more dry spells as the former.
Decline in average total monsoon rain
It has been discovered that although the average total rainfall during the monsoon season has declined, the variability of rainfall during the peak monsoon months has increased. In particular, the researchers observed increases in the intensity of wet spells and in the frequency of dry spells.
Change in atmosphere
The team also found changes in the atmosphere – such as winds and moisture –that are likely to be responsible for the changes in wet and dry spells. Diffenbaugh, also an associate professor of environmental Earth system science said that the next step is to investigate what might be causing the changes in the atmosphere.
These revelations have been published in the 28th April issue of the journal Nature Climate Change and are the result of a new collaboration between climate scientists and statisticians that focused on utilizing statistical methods for analyzing rare geophysical events.
Photograph by Stanford School of Earth Sciences
