Millennium Post

El Niño climate cycle and poor monsoons

India’s crucial south-west monsoon season is coming to an end. With less than ten days to go in the official wind up of the season, India is all set to witness another year of below-normal rain. All India seasonal rainfall departure will set close to -15 per cent (with slight variance possible). A departure of -15 per cent means rain has been 15 percent below normal. As per India Meteorological Department (IMD), a departure of -15 per cent comes under a broad “normal” rain category that runs from +19 per cent to -19 per cent. However, things aren’t that normal in most of the 16 (out of 36) meteorological subdivisions that to date have recorded “deficient” rain. With a departure of -46 per cent between June 1 and September 20, Eastern Uttar Pradesh tops the list. It is followed by Western Uttar Pradesh at -44 per cent, Punjab at -41 per cent and Haryana at -39 percent.

This year’s monsoon has been dicey and full of ups and downs. Speculations about El Niño affecting India’s monsoon were there since early 2015. But the first blow to the chances of a good monsoon came on April 22 when the IMD issued the first part of Long Range Forecast (LRF) of the monsoon. This suggested that India would get 93 percent of normal rain of 89cm (with a variance of plus-minus 5 percent). On June 2, in the second part of LRF, IMD downgraded their previous forecast. The updated forecast suggested that India would get 88 percent of normal rain during the monsoon period (variance of plus-minus 4 percent). But, to everyone’s surprise, the monsoon’s mood remained very good during the onset phase (i.e., in June). In this month, India received 16 percent of normal rain. Thirteen subdivisions recorded excess rain, 20 recorded normal rain and only 3 recorded deficient rain. 
The performance of rain was impressive in Jammu and Kashmir, Rajasthan, Western Madhya Pradesh and other parts of Central India. This was welcoming news for the citizens, and it even brought back their hopes of a normal monsoon. Already debt-ridden but encouraged by good rain, farmers in drought-prone areas of Maharashtra like Marathwada took fresh loans and invested heavily in their fields in June hoping for a good harvest. The situation was similar in other parts of India too. No one even imagined what was in the offing.

Come the fourth week of June, things started changing. Central India witnessed a big dry spell of the monsoon that lasted for around one month. Such dry and wet spells are regular features during the season. Their intensity, frequency and time of occurrence play a very vital role in monsoon’s performance, which in turn, influences the agricultural productivity. But, the one-month long dry spell that Maharashtra, Gujarat and Madhya Pradesh witnessed was very severe. It severely damaged the Kharif crops and even led to their complete destruction at many places in Marathwada and western Maharashtra (Madhya Maharashtra) where irrigated area is too less. It also kicked off drought conditions and agrarian crisis in these areas, leading to an acute shortage of drinking water and fodder for thousands of cattle. For the first time in the history of Maharashtra, cattle shelters were set up in the month of August in Marathwada. At the end of July, India’s seasonal rain that was 16 percent above normal in June came down to 5 percent below normal. The trend continued in August, due to which the amount of seasonal rain further came down to 11 percent below normal. And on September 20, we are at 14 percent below normal. This is how June’s rain fooled the farmers in suicide-prone areas of Maharashtra. The farmers wouldn’t have gone for early sowing had June’s rain been scanty and in such a case, the loss certainly would have been lesser than what it is right now.

The overall poor performance of the monsoon confirms the influence of suppressing factors like El Niño. But why was June an exception? Where was El Niño in June? Was it absent?

The impact of El Niño was very much present in the month of June! It was trying its best to suppress India’s monsoon, but it was the Madden-Julian Oscillation (MJO) which gave it a “fight”. MJO was discovered by two atmospheric researchers—Roland Madden and Paul Julian in the early 1970s. Simply put, MJO is an atmospheric disturbance that travels around the world in the tropical regions over an average period of 30-60 days. This disturbance propagates eastwards with time and with varying intensity. The most important property of MJO is that it influences the clouds/rain i.e., the process of convection in the areas it travels through. 

It has two “faces”. One face or phase boosts the process of clouds/rain (called the wet phase) while the other one suppresses it (called the dry phase). India’s monsoon gets benefitted whenever there are wet phases over the nation. This is because such a phase helps in the rising motion of moist air, which is necessary for cloud formation. The more intense it is, the more rain that particular region gets. In a sense, it counters the negative effects of El Niño for a certain period. But when a dry phase enters, it suppresses the rainfall and under the prevailing El Niño conditions, the suppression factor is pretty strong. MJO has dipole nature as can be seen from the above image. Over India, there is a wet phase, but over the Pacific there is a dry phase at the same time. This is because the warm, moist air that rises over India diverges and cools at upper levels of the atmosphere. This cool and dry air then sinks over the Pacific causing lack of clouds/rain there.

MJO became active in early June of this year, and the Indian subcontinent was blessed with one such wet phase. It continued its presence till the middle of the month that helped the monsoon onset and also gave bountiful rain. But shortly after this, a strong dry phase entered the subcontinent and maintained its presence till mid-July. This dry phase was likely the strongest one seen over India in the last few years. This was the reason central and other parts of India witnessed such a big dry spell between June-end and July-end. MJO activity has been weak since July due to which the El Niño has maintained its hold over India’s monsoon.

(The author is an independent <g data-gr-id="89">weather</g> forecaster. Views expressed are personal)
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