Friday, 17 May, 2024
By: Anshul Vipat
While such unsual rains in October is considered normal, there is a definite change in pattern which needs to be looked into
This erratic rainfall in October has happened for the third time in a row
On paper, the monsoon rains in North India were supposed to cease two weeks ago, as the average date of monsoon’s complete withdrawal from the region falls on September 30. But this time the rains overstayed their welcome in North and Northwest India spilling over into the second week of October now. And while it has brought down the temperature in the national capital, bringing cheers to the citizens, it has created havoc in certain places flooding fields and soaking standing crops, leading to grain loss.
Rainy October
According to the data collected by the India Meteorological Department (IMD), Uttar Pradesh has collectively recorded 145.3 mm of rainfall in the first 12 days of October, registering surplus rains of a whopping 657 percent. Delhi, on the other hand was over welcomed by the rain showers recording 128.2 mm of rain so far this month — its highest October precipitation in 66 years! Its wettest October in recorded history was seen back in 1954, when it registered an all-time high rainfall worth 238.3 mm. The city did not receive any rain in October 2020, 2018 and 2017 and logged 47.3 mm of rainfall in October 2019.
Some states in northwest India, which were reeling under severe deficits, witnessed a complete reversal in a matter of days. A deeper dig into IMD data shows that between October 1-7, eight states across the country received large excess rainfall (more than 60 percent excess) and four received excess rainfall (20 to 59 per cent excess). Three states - Haryana (577 percent), Uttarakhand (538 percent), Uttar Pradesh (698 percent) and as many as 213 districts (30 percent) received large excess rainfall in the period, while 75 (11 percent) received excess rainfall. India as a whole received 33 percent more rainfall than normal for the period.
According to the weather department, the excess rainfall is a result of the interaction of monsoon winds, moving east to west, with the western disturbance wind system. Such interactions happen several times during the monsoon season. While such interactions are normal, there is a definite change in pattern which needs to be looked into.
The changing monsoon pattern
IMD stops recording monsoon data on September 30. Any rainfall after this date is counted as ‘post-monsoon rainfall’. However, this erratic rainfall in October has happened for the third time in a row. A similar rainfall stretch into October had also happened in 2021 and the year before that. In 2021, nearly half of all districts in the country received 20-60 percent excess rainfall in the first week of October. Country-wide excess of rainfall in October 2021 stood at 23 per cent.
Source: Indian Meteorological Department
Then there's more to it. The southwest winds which causes rainfall generally recedes from North India by September 17. This year, it began receding on September 30. Last year, this took place on October 25 and was the seventh-most delayed monsoon withdrawal between 1975 and 2021. In 2020, it commenced on September 28 and withdrew on October 28. In 2019, monsoon withdrawal commenced on October 6 and withdrew by October 15.
The La Lina effect
Monsoon in India is has been impacted by two factors - La Nina and negative Indian Ocean Dipol. The former refers to large-scale cooling of the ocean surface temperatures in the central and eastern equatorial Pacific Ocean coupled with changes in changes in the tropical atmospheric circulation which affects climate patterns in different parts of the world. Negative Indian Ocean Dipol happens when waters near the eastern Indian Ocean are warmer than normal. India is seeing an extended spell of the La Nina, called a ‘triple dip’ La Nina which is a phenomenon lasting across three winter seasons in the northern hemisphere. This is only the third time since 1950 that a triple dip La Nina has been observed. This, in part, is why for the third year in a row, India is seeing surplus rain.
Monsoon which delivers over 70 percent of the country's rainfall is considered the lifeline of India's agriculture-dependent economy. The monsoon impacts inflation, jobs, and industrial demand. Good farm output keeps a lid on food inflation. It is significant at the time when country is battling record breaking retail inflation which has galloped to a retail inflation has galloped to a six-month high at 7.8 percent.
