El Nino - Southern Oscillation

“normal” or “neutral” Equatorial trade winds blow westward Water “piles up” in western Pacific Ocean Water is warmer in western Pacific Ocean Upwelling of colder water in eastern Pacific Ocean Normal precip patterns

What is the jet stream? Current of air flowing 150 to 300 mph High in troposphere (about 10 km) Over the boundary between 2 air masses. Usually blows from west to east. Aircraft can use or avoid a jet stream.

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What causes the jet stream? The temperature difference between 2 air masses. The greater the temp. diff., the faster the jet stream. Seasons (temp. diff.) can cause jet stream to shift position. Also the ENSO.

El Nino Tradewinds slow and/or stop Warm water covers more of equator No upwelling in eastern Pacific Ocean (collapse of fishing industry in Peru) Global change in weather patterns

NOAA / PMEL / TAO Project Office / El Niño Theme Page What are La Niña, El Niño and Normal Conditions in the tropical Pacific Ocean? See What is La Nina? Go to the El Niño Theme Page oar.pmel.taogroup@noaa.gov Disclaimer | Privacy Policy La Niña is characterized by unusually cold ocean temperatures in the equatorial Pacific. El Niño is characterized by unusually warm ocean temperatues in the Equatorial Pacific Ocean. These are graphics of the Reynolds Sea Surface Temperature (SST) analysis from the National Center for Environmental Prediction (NCEP) for the entire Pacific Ocean (70N to 70S). Also see plots of the Sea Surface Temperature Anomalies (the amount that the temperature differs from the normal value for the month). Also available is a graph of sea surface temperature for the entire Pacific Ocean. Graphics are provided by the TAO project and created by Dai McClurg. You can also see animations of the Reynolds SST and TAO buoy SST from the TAO realtime data page.

El Niño effect during December through February. El Nino Dec - Feb

La Nina Increased velocity of westward tradewinds Colder water along more of equator (eastern end) Global change in weather patterns

La Niña effect during December through February.

La Niña effect during June through August.

How to forecast the ENSO cycle? Need info about SST, ocean temperatures at depth and winds.

Array of TAO/TRITON Approx 70 moorings w/ about 400 buoys Completed Dec 1994 after 10 years 17 ships on 83 cruises from 6 countries (multi-national) In Oct 1999, Japan assumed responsibility for western Pacific moorings (TRITON)

TAO/TRITON Tropical Atmosphere & Ocean Motivated by 1982-83 El Nino event

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What is the Tropical Atmosphere-Ocean Moored Buoys of the Tropical Atmosphere-Ocean Array                                                               What is the Tropical Atmosphere-Ocean

Data from TAO/TRITON Wind velocity SST (sea surface temperatures) Air temp 10 sub-surface temp’s to depth of 500 meters

Put the TAO/TRITON data into a computer model Now can forecast path of storm track

                                                           Note that the location of the jetstream is influenced by the location of the convection, e.g. the main mean jetstream for La Niña starts to the left of the normal scenario. These are the teleconnections to our mid-latitude weather.

Benefits of accurate ENSO forecasts (hopefully, with predictions up to one year)

Drought forecasts Preparation for wildfires Cultivation of drought-tolerant crops Plan food distribution in developing countries

Forecast of Excessive Precipitation Preparation for extremes: hurricanes, tornadoes, etc Preparation for local flooding: mudslides Mosquito control in malarial zones Planting of wet-tolerant crops

Forecast of change in ocean temperatures Predict profitable fishery sites Monitor health of coral reef ecosystems

Economic benefits from forecasts Adjust the production of weather-related goods: vehicles, clothing, shelter Adapt use of recreational facilities: skiing, snowboarding, boating Prepare for fluctuations in consumption of home-heating fuels

Review What is ENSO?

ENSO The El Nino-Southern Oscillation Cycle During normal years, equatorial trades blow west Ocean is 0.5 m higher & warmer in western Pacific Upwelling currents in eastern Pacific 20 – 30 cm annual precip in San Diego (8 to 12 inches)

b. Normal scenario                                                                   

What happens during El Nino?

a. El Niño                                                                  

What happens during La Nina?

                                                                  

                 Note that the location of the jetstream is influenced by the location of the convection, e.g. the main mean jetstream for La Niña starts to the left of the normal scenario. These are the teleconnections to our mid-latitude weather.

For more info about ENSO search NOAA For more info about ENSO

The end