The 2020 summer monsoon has completed half of its four-month season in the Indian subcontinent. Usually, by this time, one gets a clear sense of whether it has performed according to its usual pattern or has slipped. These two months — June and July — are also critical for agriculture that defines the livelihoods of close to 50 per cent of Indians.
1. The rainfall has yet been 0.6 per cent above the long period average (LPA). But there is variation on rainfall between regions. The eastern and northeastern regions have received 11.6 per cent excess rainfall over the LPA figure. But northwest India has 19.7 per cent deficit rainfall in comparison to the LPA figure.
2. The monsoon has not followed its normal pattern in July, after a wet June. India received 9.8 per cent less than normal rainfall in July.
3. The monsoon seemed to have entered into a deficit scenario in June and July, though not officially, as even up to a 19 per cent deficit from normal rainfall is considered ‘normal’ by definition.
All four regions — northwest, east and northeast, central and south peninsular — reported above normal rainfall in June, in the range of three to 30 per cent. In July, two regions reported deficit rainfall — northwest (deficit by 28.5 per cent) and central (deficit by 20.3 per cent).
4. By July 22, nearly 70 per cent of India’s 684 districts reported normal, excess or large excess rainfall. These districts reported rainfall above the LPA figure, in the range of 19-60 per cent.
However, these districts experiencing ‘above normal’ rainfall were mostly in five states — Tamil Nadu, Karnataka, Uttar Pradesh, Bihar and Madhya Pradesh.
5. Nearly 15 per cent of districts in India reported large excess rainfall or above 60 per cent excess from the LPA figure. This is five times the number in 2019 and the highest in the last six years. Fifty-two per cent of these districts are in four states — Tamil Nadu, Karnataka, UP and Bihar.
6. But 27 per cent of India’s districts reported deficit monsoon by the mid-season. These districts — 185 in number and mostly from Gujarat, Rajasthan, MP, UP, and Jammu and Kashmir — received up to 59 per cent less rainfall than the normal figure.
7. RK Jenamani, senior scientist, National Weather Forecasting Centre, said, “July 2020 has been a big dampener, with the total absence of any low-pressure systems (LPS) forming over the Bay of Bengal. LPSs are major rain-bearing systems. Their presence keeps the monsoon at its day-to-day scale intact, with the monsoon trough zone. Due to the LPS’ absence, the eastern end of the monsoon trough has a tendency to move towards the foothills of the Himalayas more frequently in July.”
This also explains the deficit rainfall in the core zones of the monsoon in July. In 2002, a drought year, there were very less LPSs during the first two months of the monsoon season.
8. July accounts for the highest rainfall during the monsoon season. Usually, 33 per cent of the total rainfall of the season falls in July. This also makes this month critical for agriculture as the paddy crop cycle has evolved according to this rainfall pattern.
9. A deficit in July rainfall has historically been associated with an overall deficit monsoon and severe droughts. Farmers transplant paddy crops during July and these need regular showers to survive. This year is also important from the agriculture perspective as rice acreage (net sown area) has increased by 17.3 per cent over the last year.
10. Deficits in the monsoon in July have caused six of India’s worst droughts between 1877 and 2005, according to an analysis of India Meteorological Department rainfall data by the Indian Institute of Tropical Meteorology (IITM), Pune.
IITM scientists studied overall monsoon outcomes for rainfall above or below normal for June, July as well as both, using data since 1871, in 2013. If there was a deficit in July, chances of overall deficiency soared to more than 90 per cent, they found. The study also found that with deficit rainfall in June, chances of a deficit in the overall monsoon were around 77 per cent.