El nino and la nina

About a decade ago I showed that this phenomenon amplifies the climate variability everywhere it strikes, including Australia.

El nino and la nina

Warmer water near the surface of the ocean, heated by the sun, is blown to the west by the trade winds. Warmer water "piles up" in the west Pacific the sea surface is about one and one half feet higher at Indonesia than at Ecuador as cooler water rises from deep in the ocean in the east Pacific to replace the water that was moved away by the winds.

The sea surface temperature is about 8 degrees C higher in the west, with cooler temperatures in the east Pacific due to upwelling of colder water from deep in the ocean. Rainfall develops much more frequently in rising air over warm water so normal rainfall amounts are higher over the west Pacific and the east Pacific area is relatively dry.

This leads to warmer water temperatures in the eastern and, especially, central Pacific because upwelling is reduced. As the pool of warmer water moves eastward, the areas of best rainfall development also move to the east, with associated flooding in Peru and drought in Indonesia and Australia.

The eastward displacement of this heat source the warmest water results in large changes in the global atmospheric circulation, which in turn forces changes in weather in regions far removed from the tropical Pacific. However, this interval has varied from 2 to 7 years. They typically last 9 to 18 months.

As warmer water near the surface of the ocean is blown to the west, cooler water rises from deep in the ocean in the east Pacific to replace water that was moved away. The colder water cools the overlying air which hampers the formation of clouds and tropical thunderstorms in central and eastern areas of the Pacific Ocean.

This suppression of rain-producing clouds leads to dry conditions from near the International Date Line east to South America. They tend to develop from March to June and reach peak intensity during the December to April period, weakening from May to July.

The Southern Oscillation is the see-saw pattern of reversing surface air pressure between the eastern and western tropical Pacific. When the surface pressure is high in the eastern tropical Pacific it is low in the western tropical Pacific, and vice-versa.

The reduction in the pressure gradient is accompanied by a weakening of the low-latitude easterly trades. These stations are used because of their long data records.

El nino and la nina

What does ENSO-neutral mean? During ENSO-neutral periods the ocean temperatures, tropical rainfall patterns, and atmospheric winds over the equatorial Pacific Ocean are near the long-term average. The winds in the western Pacific are very weak see the arrows pointing in the direction the wind is blowing towardsand the winds in the eastern Pacific are blowing towards the west towards Indonesia.

The bottom panel of the December plot shows anomalies the way the sea surface temperature and wind differ from a normal December. In Decemberthe warm water red in the top panel of the December plot has spread from the western Pacific Ocean towards the east in the direction of South Americathe "cold tongue" green color in the top panel of the December plot has weakened, and the winds in the western Pacific, usually weak and towards the west, are blowing strongly towards the east, pushing the warm water eastward.

This results in an exceptionally stormy winter and increased precipitation across California and the southern U. Also, there is an enhanced flow of marine air into western North America, along with a reduced northerly flow of cold air from Canada to the United States.

These conditions result in a milder than normal winter across the northern states. Large portions of central North America experience increased storminess, increased precipitation, and an increased frequency of significant cold-air outbreaks, while the southern states experiences less storminess and precipitation.

Equatorial Pacific sea surface temperature anomalies do not always directly correlate with typical ENSO conditions, particularly if other environmental indices such as the Pacific Decadal Oscillation offset these conditions.

One significant effect associated with this pattern is cooler than average temperatures over the southeast United States. This pattern also increases the transport of moisture from the Gulf of Mexico, which results in wetter than normal conditions over the Gulf Coast states.

As a result, the Deep South experiences drier and warmer conditions than would normally be expected.El Niño and La Niña are the warm and cool phases of ENSO (pronounced “en-so”).

ENSO is the most influential natural climate pattern on Earth. ENSO swings back and forth every few years. El Niño and La Niña affect both the ocean and the atmosphere. Periods of weaker- or stronger-than-average easterly trade winds initiate El Niño and La Niña.

El Niño and La Niña are the warm and cool phases of a recurring climate pattern across the tropical Pacific—the El Niño-Southern Oscillation, or “ENSO” for short.

The pattern can shift back and forth irregularly every two to seven years, and each phase triggers predictable disruptions of temperature, precipitation, and winds. Dec 12,  · SST Niño Regions - Graphical depiction of the regions (i.e. "NINO Boxes") most commonly used in the diagnosis and forecast of El Nino.

Other El Niño Links - Links to the most informative El Niño/La Niña links on the web. El Niño–Southern Oscillation (ENSO) is an irregularly periodic variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean, affecting climate of much of the tropics and subtropics.

The warming phase of the sea temperature is known as . Mar 05,  · Well I’m not a weather / climate guru or geek, but I always thought that “El Nino” originated off the coast of Peru, when all the rookery birds starved, along with the coastal fishing communities, because the bait fishes took off for cooler waters.

El Niño and La Niña are the warm and cool phases of a recurring climate pattern across the tropical Pacific—the El Niño-Southern Oscillation, or “ENSO” for short.

El Niño–Southern Oscillation - Wikipedia