El Nino Southern Oscillation. What’s this? “Normal” or “Neutral” Equatorial trade winds...

El Nino Southern Oscillation

What’s this?

“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 precipitation 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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US National Weather Monday

Monday US Jet Stream Forecast

US National Weather Wednesday

Wednesday US Jet Stream Forecast

What causes the jet stream?

• The temperature difference between 2 air masses

• The greater the temperature difference, the faster the jet stream

• Seasons can cause the jet stream to shift position. Also 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?

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.

See What is La Nina?Go to the El Niño Theme Page oar.pmel.taogroup@noaa.gov Disclaimer | Privacy Policy

                                El Niño effect during December through February.

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.

 Back:  El Niño

How to forecast the ENSO cycle?

Need info about SST, ocean temperatures at depth, and winds

Array of TAO/TRITON

• Approximately 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

Array configuration

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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 temperatures to a 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?

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.

Search NOAA

For more info about ENSO

The end