NEW DELHI: India has recorded an overall above-normal (107%) southwest monsoon (SWM) rainfall between June and September. The season has kept the Gangetic plain dry while the arid region wet. However, scientists are confused over the factors that drive bountiful monsoon.
Between June 1 and September 27, India got 918 mm rainfall compared to the normal seasonal rainfall of 868.8 mm. The India Meteorological Department (IMD) counts the SWM period between June 1 and September 30. This year, this period marked record depression and low-pressure area events.
However, scientists are confused over the factors that drive bountiful monsoon. “This year, the SWM is bountiful despite the absence of the La Nina factor,” said a scientist, “We are clueless about the factors that drive above normal rainfall.”
The IMD had predicted the emergence of La Nina factor (cooling of equatorial Pacific Ocean) during the second half of the monsoon, but failed. But the El Nino (warming of equatorial Pacific Ocean) factor was at neutral conditions. Last year, the El Nino factor suppressed the monsoon and brought it to the deficit category.
In India, El Nino is synonymous to poor monsoon, and La Nina to bountiful monsoon.
Further, a peculiar pattern of SWM has also been observed. While the Gangetic plain got deficient rainfall, India’s arid region has received excess rainfall. Experts underline the impact of climate change.
Of the 36 meteorological sub-divisions, four sub-divisions recorded deficient rainfall, which include Punjab and Arunachal Pradesh (-29%), followed by Jammu & Kashmir (-26%) and Bihar (-23%). However, arid regions like West Rajasthan received a record 71% followed by Saurashtra and Kutch, which got 69% excess rainfall.
“It is a clear sign of the impact of climate change, which has been shifting the rainfall trend,” said Mahesh Palawat of Skymet Weather.
Curiously, the SWM arrived early, and its departure was quite late. The SWM has started withdrawing from September 23 against the normal date of September 17.