El Nino has been in the news recently as the National Oceanic & Atmospheric Administration (NOAA), in its latest (April 2015) findings, has predicted a 70% chance of 2015 being an El Nino year.
What is El Nino?
* El Nino refers to a complex series of climatic changes caused by the presence of warmer than average sea surface temperatures in the Pacific Ocean off the coast of Ecuador and Peru.
* This abnormal warming leads to increased evaporation and concentrated cloud formation activity around South America, causing heavy rains there.
* The other end of tropical Pacific Ocean – Indonesia, Papua New Guinea and Australia – is deprived of rain-bearing winds, resulting in low rainfall and drought. These effects may spread to India and its surrounding regions as well.
Why is it called ‘El Nino’ and how long does it last?
*In Spanish, El Nino means ‘Little Boy’ or ‘Boy (Christ) Child’. Fishermen off the Pacific coast in Southern America started using this name as this phenomenon occurred during the month of December (around the time of Christmas) roughly every 2 – 7 years.
* However, El Nino begins to form around the months of June and August. It reaches its peak strength between December and April and it weakens between May and July of the following year.
What is the impact of El Nino on various countries?
* Due to El Nino, the coast of Northern Peru and Ecuador experiences warm and wet climate in the months of April – October. In extreme cases, this could lead to floods. Similarly, the southern part of Brazil and northern Argentina experience rainfall in spring.
* The impact of El Nino is far stronger in South America than in North America.
* In North America, most El Nino winters are moderate in western Canada and in parts of the northern United States and are wet near the southern states from Texas to Florida.
Is this year going to be an El Nino year?
* As per the NOAA prediction in April 2015, there is 70% chance of 2015 being an El Nino year. Do note that the NOAA has predicted a weak El Nino this year.
The recent warming of ocean waters near the International Date Line and along the Equator has prompted NOAA to say that we now have a very weak El Nino event.
The latest sea-surface temperature data does show some “dramatic warming” within the last several weeks along the West Coast of South America and westward along the Equator to the International Date Line.
Since late March, it seems that readings have climbed to at least several degrees above normal near the South American West Coast. There are a few spots with temperatures over 3 degrees above average levels.
The Australian Bureau of Meteorology says this recent warming may signal another El Nino event. They say, “There is about a 50 percent chance of El Nino developing in the coming months, which is twice the normal likelihood.”
If this warm water phenomenon hangs on into the summer season, the tropical storm and hurricane season in the Atlantic Ocean will likely be less than the normal 11 named systems. However, there have been hurricanes, and a few strong ones, during an El Nino year.
As mentioned earlier, this El Nino is relatively weak at this point. During this type of pattern, there is more ‘wind shear’ to the region. With wind shear, the speed and direction of the wind changes between different altitudes which often inhibits the hurricane formation.
Several hurricane forecasters are predicting for a very quiet Atlantic hurricane season in 2015. They believe it could be the season with the least activity since the mid-20th century. By contrast, a hurricane cycle prediction company states that El Nino will fade in August and this season may be the most dangerous in at least 3 years.
Global Weather Oscillations says that “3 hurricane or strong tropical storm landfalls are likely along the United States coast.” They also state that “the next 3 seasons will be the most dangerous in 10 years.”
Whether the Atlantic and Caribbean area will see a quiet or active season, the Pacific Ocean usually reports more tropical storms and hurricanes during an El Nino year.
That doesn’t mean more hurricanes everywhere, though: While El Niño tends to boost activity in the Pacific Ocean, it clamps down on storm formation in the tropical Atlantic. That link has at least one hurricane forecaster calling for a very quiet Atlantic hurricane season this year — possibly the quietest since the mid-20th century.
While El Niño is a cyclical climate phenomenon in the Pacific Ocean — marked by warmer ocean temperatures in the tropics and a weakening of the usual easterly trade winds — it can impact weather around the globe.
The most recent El Niño observations and climate model projections suggest the front of current event possibly forecasters are cautious.
Extending climate predictability beyond El Nino
Tropical Pacific climate variations and their global weather impacts may be predicted much further in advance than previously thought, according to research by an international team of climate scientists from the USA, Australia, and Japan.
The source of this predictability lies in the tight interactions between the ocean and the atmosphere and among the Atlantic, the Pacific and the Indian Oceans. Such long-term tropical climate forecasts are useful to the public and policy makers.
At present computer simulations can predict the occurrence of an El Niño event at best three seasons in advance. Climate modeling centers worldwide generate and disseminate these forecasts on an operational basis.
Scientists have assumed that the skill and reliability of such tropical climate forecasts drop rapidly for lead times longer than one year.
The new findings of predictable climate variations up to three years in advance are based on a series of hindcast computer modeling experiments, which included observed ocean temperature and salinity data. The results are presented in the April 21, 2015, online issue of Nature Communications.
Source | News Agencies