At 109% LPA, 2020 monsoon saw third highest rains after 1994 and 2019

Vibha Sharma
Tribune News Service
New Delhi, October 1

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With 109 per cent of the Long Period Average (LPA), the 2020 monsoon registered third highest rains after 112 per cent LPA (1994) and 110 per cent LPA (2019), the IMD said on Thursday.

The southwest monsoon, which ended its four-month run officially yesterday, received 95.8 cm between June 1 and September 30 against the long period average of 88.0 cm based on data of 1961-2010 (109% of the LPA)

Considering the recent years since 1990, the all India seasonal rainfall this year was third highest, as per the IMD’s end of season report.

This also makes 2019 and 2020 two consecutive years with above normal monsoon rainfall after 1958 (110% of LPA) and 1959 (114% of LPA). The year also saw an over-active August with back to back low pressure systems over the north Bay of Bengal.

Of 36 meteorological subdivisions, two received large excess, 13 received excess and 16 subdivisions received normal monsoon rainfall. Of the five subdivisions that received deficient rains are Nagaland, Manipur, Mizoram and Tripura (-32%), West Uttar Pradesh (-37%), Uttarakhand (-20%), Himachal Pradesh (-26%), Jammu & Kashmir and Ladakh (-34%)

As on October 1, monsoon has withdrawn from Punjab, western Himalayan region, Haryana, Chandigarh, Delhi and many parts of Rajasthan and some parts of Uttar Pradesh.

The withdrawal line is currently passing through Lakhimpur Kheri, Shahjhanpur, Alwar, Nagaur.

Meanwhile, according to a study by the Wadia Institute of Himalayan Geology (WIHG) global climatic events like the Roman Warm Period, Medieval Climate Anomaly, and the Little Ice Age may have had significant impacts on India’s landscape, vegetation, and socio-economic growth, with abrupt shifts in the Indian monsoon coinciding with these climatic events.

The study carried out with lake sediments from Rewalsar Lake, a freshwater lake from Mandi district of Himachal Pradesh, could resolve the long debate among scientists about whether such events were local or global.

Sediments from this lake preserve signature that can be used as proxies to understand monsoon variability in the past, says an official statement by the DST.

The study shows wet monsoon conditions in the north-western Himalaya between 1200 and 550 BCE. This condition prevailed till 450 AD, coinciding with the Roman Warm Period (RWP).

It was followed by reduced precipitation and a weak ISM till 950 AD and then strengthened during the Medieval Climate Anomaly (MCA) between 950 and 1350 AD. During the Little Ice Age, there was a pronounced reduction in monsoon precipitation, as per the DST.

Graphics

*Monsoon withdrew from western parts of Northwest on September 28 against normal date September 17, a delay of around 11 days.

August saw back to back  low pressure systems over the north Bay of Bengal .

Arabian Sea was very active with strong winds reaching up to 50-60 kmph in lower levels for a few days in the month.

*Five low pressure systems formed during August 2020 which caused higher than normal rainfall over central and western part of India.

*Total number of low pressure days in August was 28 against normal of about 17