Two primary factors are observed for monsoon performance, which are Indian Ocean Dipole (IOD) and El Nino.
As per the CPC ENSO discussion of February 2019 Pacific climate has finally entered El Nino. In 2018 the position of Pacific sea was neutral. At present weak El Nino conditions are present and expected to continue as per “Pacific ENSO Applications Climate Centre”.
The above image shows the year of El Nino and La Nina. In the last shows the increasing trend of El Nino with value +0.8. (Image source: PEAC Center)
Following observations provided by “Pacific ENSO Applications Climate Centre” suggest weak El Nino condition during February.
- Above Average Sea Surface Temperature across most of the equatorial Pacific Ocean.
- Nino 4 region remained above average with a value of +0.8 degree Celsius in early February.
- Positive sub surface temperature anomalies increased in the last two weeks of February in association with a downwelling kelvin wave which contributed to above average temperature in the central Pacific.
- Compared to January the region of date line experienced more equatorial convection while anomalies remained weak over Indonesia.
Bureau of Meteorology Australian Government expecting 70 % chances of prevailing El Nino.
Though Indian Ocean Dipole also has influence over Indian Monsoon performance. But Indian Ocean Dipole will be neutral as the models.
Prediction of performance of Indian Monsoon is difficult. But above situation suggest below normal rainfall in the coming monsoon season.
The Oceanic Nino Index (ONI) value in Nino 3.4 region is crucial in declaring El Nino event. The ONI value between -0.5 to +0.5 is normal. If more than +0.5 is El Nino and below -0.5 is La Nina. At present value is +0.8.