Initially, monsoon in India commenced with an El Nino scare and practically affected the entire season. Throughout the monsoon season this year, the Pacific Ocean remained consistently warm but not good enough to be termed as El Nino.
As have been explained earlier, El Nino is an abnormal warming of surface ocean waters in the equatorial Pacific, which occurs every two to five years.
Such an event is generally characterized by occurrence of normal tropical storms and Hurricanes in Eastern Pacific and decrease in storms in the Atlantic, Gulf of Mexico and the Arabian Sea. Higher the temperature, lower the pressure, which in turn changes the wind pattern and impacts rainfall figures. All El Niño’s are not the same, nor does the atmosphere always react in the same way from one El-Nino to another.
El Nino has a strong connection with Indian Southwest Monsoon
El Nino is closely associated to Monsoon in India, which is often weaker during occurrence of such a phenomenon. During an El Nino, monsoon never witnesses excess rainfall baring few exceptions. A poor Monsoon in India seemed the order of the day till February and as we entered mid-April, these observations were turning out to be more accurate. Other meteorological agencies across the world also strongly pointed towards the likelihood of an El Niño weather pattern this year.
El Nino leads to warming of sea surface temperature (SST) above 0.5oC. From the 21st to 25th of May, the surface temperature remained constantly at 0.6oC. This could be attributed to poor performance of Monsoon in India with rain deficiency at 43% till 12th of July. Thereafter, conditions relaxed and rain deficiency came down to 22% by end of July as the surface temperature in the equatorial Pacific came down to 0oC and even further to -1 oC.
The month of July received 10% below normal rainfall while August was 9.2% below normal. As of now, September has received 19% above normal rainfall but it is likely to decline and end up with a surplus of 10% only.
Equatorial Pacific is divided into four parts Nino 3, Nino 4, Nino 3.4, Nino 1+ 2, for Meteorological analysis. Any occurrence over Nino 3.4 is the most relevant for Monsoon in India. The Pacific Ocean is now showing a rise in temperatures, here’s a look at the surface temperatures since August-
| Date (2014) | Nino 3 | Nino 4 | Nino 3.4 | Nino 1+ 2 |
| August 4 | 0.2oC | 0.3oC | - 0.1oC | 0.6oC |
| August 11 | 0.4oC | 0.5oC | 0.0oC | 1.2oC |
| August 18 | 0.5oC | 0.4oC | 0.0oC | 1.2oC |
| August 25 | 0.5oC | 0.4oC | 0.3oC | 1.4oC |
| September 2 | 0.4oC | 0.5oC | 0.4oC | 0.8oC |
| September 16 | 0.4oC | 0.7oC | 0.5oC | 0.7oC |
| September 22 | 0.4oC | 0.8oC | 0.5oC | 0.7oC |
This could be the last update by Skymet on El Nino index, as far as Indian monsoon is concerned.
- The table above shows persistent warming of the Ocean waters giving rise to neutral conditions.
- Positive equatorial sea surface temperature (SST) anomalies continue across most of the Pacific Ocean.
- As reiterated by Skymet, El Nino is still evolving. As per latest updates, the chances of El Nino occurring this year still stands at 60-65%, peaking during fall and winter in the Northern Hemisphere.
Rainfall Figures from June to September
The figure above depicts total rainfall from June to September over Equatorial Pacific Ocean, Equatorial Indian Ocean and the Indian Subcontinent. We can clearly see that rain in the Indian Ocean was confined to the eastern half, substantiating poor monsoon in India. Rain in the western part accounts for good monsoon in India and vice versa.
