El niño is Spanish for "the boy", and the term El Niño refers to the Christ child, Jesus, because periodic warming in the Pacific near South America is usually noticed around Christmas.
El Niño events tend to begin in early Summer (Northern Spring), mature during Summer and Late Summer (Autumn), then begin to decay in Winter (of the Northern Hemisphere), with the event generally ending in the Spring (or early Summer) of the following year. The greatest impact normally occurs during the Summer period.
El Niño is a band of anomalously warm ocean water temperatures that periodically develop off the Pacific coast of South America.
El Niño is defined by prolonged warming in the Pacific Ocean sea surface temperatures when compared with the average value. The accepted definition is a warming of at least 0.5°C (0.9°F) averaged over the east-central tropical Pacific Ocean. During El Niño years, the trade winds weaken and the central and eastern tropical Pacific warms up. This change in ocean temperature sees a shift in cloudiness and rainfall from the western to the central tropical Pacific Ocean.
Typically, this anomaly happens at irregular intervals of two to seven years, and lasts nine months to two years
ENSO is the oscillation between El Niño and La Niña conditions.
The first signs of an El Niño are:
Rise in surface pressure over the Indian Ocean, Indonesia, and Australia
Fall in air pressure over Tahiti and the rest of the central and eastern Pacific Ocean
Trade winds in the south Pacific weaken or head east
Warm air rises near Peru, causing rain in the northern Peruvian deserts
Warm water spreads from the west Pacific and the Indian Ocean to the east Pacific. It takes the rain with it, causing extensive drought in the western Pacific and rainfall in the normally dry eastern Pacific.
Current Year Situation:
Trade Winds:Westerly wind anomalies are present over the western tropical Pacific, and a reversal of the trade winds (i.e. winds becoming westerly in the equatorial region) in the western Pacific has extended east to the Date Line; this is the first time this has occurred since the 2009–10 El Niño.
During El Niño events there is a sustained weakening of the trade winds.
SST: SST in the last 2 weeks have risen in the Nino 3 and NINO 3.4 regions by about 0.5c..while NINO 4 shows no change.
Report of Bur. of Met (Austrailia) states: "While, due to the changes in the trade winds mentioned above, the Sub Surface Sea temperatures have started rising.This pool of warmer-than-average water reached more than 5 °C above average around 150 m depth in the central Pacific."
If this pool of warmer-than-average sub-surface water rises to the surface in the eastern tropical Pacific this may lead to surface warming and the formation of an El Niño.
SOI: Having peaked at +14 recently, the SOI values have started falling, and averaged -12.6 by 23rd March..--the lowest 30-day value since March 2010— Having fallen thus, we are steading towards a El-Nino situation.
Cloudiness Report From BoM Australia: "Cloudiness near the Date Line has generally been above average from late February.
Cloudiness along the equator, near the Date Line, is an important indicator of ENSO conditions, as it typically increases (negative Outgoing Long-wave Radiation (OLR) anomalies) near and to the east of the Date Line during an El Niño event and decreases (positive OLR anomalies) during a La Niña event."
Indications and current developments show a fast development of the El-Nino...and as per the various models, may reach a full fledged El-Nino status by August 2014.
Vagaries analysing the current developments sees a faster than normal rise in Central Pacific Sea Temperatures. As the sub surface heating has commenced, and is already showing anomally of 5c, may hasten the surface heating by 1/2c
El-Nino threatens to show up by June/July ...