1 Trade Winds in Equatorial Pacific. 2 ITCZ Location July January ITCZ.

1

Trade Winds in Equatorial Pacific

2

ITCZ Location

July

January

ITCZ

ITCZ

3

Equatorial Divergence vs Subtropical Convergence

upwelling downwelling

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Trade Winds Cause Variations in Sea Surface

Height

ITCZ

ITCZ

SSH

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Meridional Trends in Trade Wind Strength, Sea

Surface Height, and Currents in the

Equatorial Pacific

TradeWind Speed

Surface Current Direction

SSH (cm)

Depth (m)

HPG

westward

eastward

ITCZ

I------Conv------IDivIConI-Div-I---Conv---I

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Zonal (E-W) Trend in Sea

Surface Height

Zonal (east-west) trend in Sea Surface Height

Wind Stress

SSH

Temperature(+ = depth of EUC)

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Equatorial Undercurrent

A

A6

EUC

Velocity (m/s)

Temperature (ºC)

Velocity Cross Sections

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SST in Equatorial Pacific

ºC

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Surface Nitrate Distribution

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Photosynthesis Rates in Surface Ocean

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Cross Sections in

the Equatorial

Pacific

Temp

Salinity

Oxygen

Phosphate

Zonal Vel.

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Effect of El Nino on Anchovy Catch

El Ninos in red

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Array of Buoys Monitored by NOAA for Wind Speed, SST, Salinity, Current Velocities

The best instrumented region of the world’s ocean

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Sea Surface Temperature Changes

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Weakening of Trade Winds during El Nino

Normal

El Nino

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Atmospheric Circulation and

Precipitation Changes during

El Nino

Normal

El Nino

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SST and Chlorophyll during El Nino

El Nino

Normal

9

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Animation of SST Anomalies during El Nino of 1997

• http://www.cdc.noaa.gov/map/clim/sst_olr/old_sst/sst_9798_anim.shtml

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History of Southern Oscillation Index(and correlation with El Nino events)

ENSO Index

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Change in Zonal Atmospheric

Circulation in Equatorial Pacific

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Global Weather Anomalies during El Nino

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Global Weather Anomalies during La Nino

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El Nino Effects on US Temperatures (Winter)

Warmer in northern midwest and cooler in south

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El Nino Effects on US Precipitation (Winter)

Wetter in southeast US

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El Nino Effects on Jet Stream

position and US Weather

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Currently El Nino Conditions (Nov 2009)

SST anomaly is currently 1-4ºC warmer than normal (avg.= 1.5ºC).