Enter March and Spring season is knocking the door. The season has a unique relation with El Niño. With Monsoon season not far away, meteorologists across the world starts tapping Nino indices as early as in January. But then comes the spring. You must be wondering about what is so special about the season and its co-relation with the world's most deadliest oceanic phenomenon.
Well in the world of meteorology, we call this season a 'Spring barrier'. A term used for ENSO predictions, it is the time when El Niño reading go for a toss. The reading which we get during this period are considered to be superficial and are not close to the real figures.
Normally, the result derived by the weather models is better and best when closest to the period of forecast. However, this is not true for ENSO forecast during the spring.
According to Skymet Weather, Spring season marks the shifting of sun from Southern Hemisphere to Northern Hemisphere. The sun crosses the Equator around March 20, which is known as 'Spring Equinox'. With this, water starts heating up with sun drawing closer. As per weathermen, rise in the sea surface temperatures reduces its gradient during this phase. This leads to weaker coupling between ocean and atmosphere. Therefore, the weather models find it harder to make an accurate forecast for El Niño conditions.
Reading the meteorological conditions and subsequent predictability of numerical models is lowest during the spring. Accordingly, ENSO signal go low and noise for the model is high As a result, predictability suffers and accuracy drops.
After the spring season is over, the ability of models to predict sharpens and rises substantially as by then sun has moved northwards, bringing down the temperatures once again.
Often El Niño and La Niña, which is of 12 months duration, generally peak during the winter months and decay thereafter during the spring. Spring is a transition time when the Nino Oceanic index inches towards neutral. However we must say that there are no definite answers or explanations as to why spring barrier exists.
Image Credit: NDTV
Any information taken from here should be credited to skymetweather.com