Tropical Pacific Oceanic Conditions during 2004-2006

1
Tropical Pacific Oceanic Conditions during
2004-2006
John Janowiak Climate Prediction Center/NCEP/NWS
OCO Annual Review - May 11, 2006
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SST Evolution
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Evolution of Equatorial Pacific SST Anomalies

• Departures increased substantially in the central
  equatorial Pacific during July 2004.
• The warmth in the central equatorial Pacific
  expanded eastward during July-October 2004.
• The warmth in the equatorial Pacific persisted
  during November-December 2004.
• Cooling occurred east of the date line during
  February.
• Warming occurred in the eastern equatorial
  Pacific during April through early May .

July 2004
Time
June 2005
Longitude
4
Evolution of Equatorial Pacific SST Anomalies
5
Evolution of Equatorial Pacific SST Anomalies
6
Evolution of Equatorial Pacific SST Anomalies
Nov 2005
Feb 2006
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SST Index
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Oceanic Niño Index (ONI)

• Three-month running-mean of SST anomalies over
  the Niño 3.4 region
• Used to place current conditions in historical
  perspective
• NOAA operational definitions of El Niño and La
  Niña are keyed to the index.

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NOAA Operational Definitions for El Niño and La
Niña
El Niño conditions positive ONI gt
0.5C. La Niña conditions negative ONI lt
-0.5C. For historical record, episode is
classified as a full-fledged El Niño or La Niña
episode when thresholds have been exceeded for at
least 5 consecutive months.
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Recent ONI Values
0.5
0.8
0.4
0.2
0.2
0.2
0.3
0.4
0.7
0.8
0.9
0.9
0.9
0.6
0.5
0.3
0.4
0.5
0.3
0.2
0.0
0.0
-0.2
-0.4
-0.7
-0.8
-0.7
-0.4?
     
11
.
.
.
.
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(5N-5S)

• MJO active
• Precip. anoms
• restricted to west
• of date line

13
active
MJO
inactive
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This was a mid-Pacific event thus the OLR
index (160oE-160oW) near-neutral
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Summary

• A weak El Niño event occurred during mid-2004
  thru early 2005,
• accompanied by active MJO
• The event was limited mostly to the mid-Pacific
• Transition to cooler-than-normal SST by Nov 2005
• Weak La Niña conditions during Nov 2005 Mar 2006