New Delhi: The India Meteorological Department (IMD) released a new benchmark number on Thursday based on data from 1971 to 2020, showing a minor drop in monsoon rainfall and overall annual precipitation in the nation over time. Certain regions, like as northeast India, had a more rapid reduction, which can be ascribed to climate change.
The new ‘rainfall normal’ value for the southwest (summer) monsoon, based on 1971-2020 data, is 87 cm, compared to the previous normal figure of 88 cm, based on 1961-2010 data. Until 2018, the IMD used 89cm as the ‘normal’ rainfall standard for the monsoon season, based on a 50-year average from 1951 to 2000.
The change is part of a routine update of typical rainfall data. The new rainfall normal was calculated using data from 4,132 rain gauge sites around the country, covering 703 districts.
Despite the fact that IMD director general M Mohapatra ascribed the decline in average normal rainfall to “natural multi-decadal epochal variability of dry and wet epochs” of allIndia rainfall, he did not rule out the potential of climate change’s influence.
“Presently the southwest monsoon is passing through a dry epoch which started in the decade of 1971-80. The decadal average of all India SW monsoon rainfall for the decade 2011-20 is -3.8% (minus 3.8%) from the long-term mean. The next decade i.e. 2021-30 is expected to come closer to neutral and southwest monsoon would enter into the wet epoch from the decade 2031-40,” said Mohapatra in an indication that the wet spell may increase the rainfall in future.
On a daily, weekly, monthly, seasonal, and yearly basis, the Met department monitors rainfall in districts, states, subdivisions, homogenous areas, and India as a whole. It generates rainfall summaries as well as percentage deviations from the average.
“This rainfall normal is prepared based on the data for the period of 50 years and is updated periodically once in every decade by incorporating the latest data from raingauge stations. The new updated rainfall normal has been prepared based on data of 1971-2020 and will replace the existing rainfall normal based on 1961- 2010 with effect from the southwest monsoon season 2022,” said Mohapatra.
Based on a 50-year analysis, the IMD discovered that the Gujarat region receives the most rainfall, accounting for 96 percent of annual rainfall, while Tamil Nadu receives the most rainfall, accounting for 48 percent of annual rainfall in the northeast monsoon season (October-December), followed by 36 percent in the southwest monsoon season.