Indian monsoons strengthened over past 15 years: MIT Study
The heightened monsoon activity has reversed a 50-year drying period during which the monsoon season brought relatively little rain to northern and central India.
A study conducted by the Massachusetts Institute of Technology (MIT) revealed that the Indian summer monsoons have strengthened in the last 15 years over north central India.
The study was published in July 2017 in the journal Nature Climate Change.
Key highlights of the study
• The heightened monsoon activity has reversed a 50-year drying period during which the monsoon season brought relatively little rain to northern and central India.
• The researchers have found that, since 2002, this drying trend has given way to a much wetter pattern, with stronger monsoons supplying much-needed rain, along with powerful, damaging floods, to the populous north central region of India. A shift in India's land and sea temperatures may partially explain this increase in monsoon rainfall.
• The researchers note that starting in 2002, nearly the entire Indian subcontinent has experienced very strong warming, reaching between 0.1 and 1 degree Celsius per year. Meanwhile, a rise in temperatures over the Indian Ocean has slowed significantly.
• The sharp gradient in temperatures, high over land and low over surrounding waters, is most suitable for stronger monsoons.
• The team tracked India's average daily monsoon rainfall from 1950 to the present day, using six global precipitation datasets, each of which aggregate measurements from the thousands of rain gauges in India, as well as measurements of rainfall and temperature from satellites monitoring land and sea surfaces.
• Between 1950 and 2002, they found that north central India experienced a decrease in daily rainfall average, of 0.18 millimeters per decade, during the monsoon season.
• To their surprise, the researchers discovered that since 2002, precipitation in the region has revived, increasing daily rainfall average by 1.34 millimeters per decade.
• The researchers also noted a brief drying period during the 2015 monsoon season that caused widespread droughts throughout the subcontinent. They attribute this blip in the trend to a severe El Nino season causing a shift in atmospheric circulation, leading to decreased rainfall in India and elsewhere.
• The team believes the current strong monsoon trend is a result of higher land temperatures in combination with lower ocean temperatures. However, it is still not clear what is causing India to heat up while its oceans cool down.