SIO 210: ENSO conclusionDec. 2, 2004

• Interannual variability (end of this lecture + next)– Tropical Pacific: El Nino/Southern Oscillation– Southern Ocean imprint of ENSO– Tropical Atlantic: dipole mode

This powerpoint was prepared for purposes of this lecture and course only. It contains graphics from copyrighted books and journals. Please do not use without acknowledgment of these sources.

ENSO: normal and La Nina conditions

http://www.pmel.noaa.gov/tao/elnino/nino_normal.html

ENSO: El Nino conditions

http://www.pmel.noaa.gov/tao/elnino/nino_normal.html

Map to show location of Tahiti and Darwin

TahitiDarwin

Walker cell: low pressure at Darwin, high pressure at Tahiti Southern Oscillation Index: Tahiti SLP minus Darwin SLP

Southern Oscilllation index (NCEP)

During El Nino:

SOI is low:

Tahiti minus Darwin is low, meaning that the pressure difference between them is reduced.

Therefore the trade winds are weaker during ENSO.

Note that Darwin and Tahiti anomalies are out of phase

El Ninos: low SOI

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/bulletin/index.html

ENSO indices: based on SST.

Most commonly used is the Nino3

or Nino3,4

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/bulletin

SOI and 110°W temperature as of this week

SST imagery - today’s image

Normal conditions in the tropical Pacific

El Nino conditions in the tropical pacific

Tropical Pacific this week

TAO Project Office PMEL/NOAA

Temperature - mean and anomalies along the equator

November 2002: El Nino November 2004: weak El Nino

Time series: SST at equator

El Nino

La Nina

SST and zonal wind anomalies, equator

SST and dynamic height anomalies, equator

El Nino-La Nina surface height

(NASA altimetry)

http://topex-www.jpl.nasa.gov/science/el-nino.html

ENSO sea surface height anomaly

http://www.osdpd.noaa.gov/

La Nina sea surface height anomaly

http://www.osdpd.noaa.gov/

This month’s surface height

(altimetry):El Nino is

not developing strongly

http://topex-www.jpl.nasa.gov/science/el-nino.html

Sea level pressure and anomalies NCEP October 2004

SST anomalies October 2004 NCEP

SST anomalies time series NCEP

ENSO - long time series of Nino3 index

Very long time series of ENSO: Kim Cobb et al. Based on corals.

Tool: Sea surface temperature pattern associated with El Nino/Southern Oscillation

Correlation of SST record at each location with the Southern Oscillation Index

ENSO (SOI) SST and SLP patterns

SOI surface zonal wind and “clouds”

ENSO global precipitation

effects

USA impacts of El Nino and La Nina: temperature

USA impacts of El Nino and La Nina: precipitation

Compare with SW US monsoon: monsoon is pretty much the same pattern as

ENSO

ENSOENSO

monsoonmonsoon

El Nino - where are we right now?

• An El Nino event is building, and predictions of this winter’s conditions in N. America are related to it.

El NinoWe are in a weak El Nino pattern now.

NOAA Climate Prediction Center winter 2004-2005 patterns prediction:

Figure 5. Seasonal U. S. temperature (left) and precipitation (right) outlooks for December 2004-February 2005. Outlooks prepared in mid-September 2004 reflect a blend of ENSO-related impacts and long-term trends.

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/

warm dry

coolwet

El Nino

Great websites:http://www.pmel.noaa.gov/tao/elnino/nino-home.html

http://topex-www.jpl.nasa.gov/science/el-nino.html