El Niño Update [23 Nov 2009]

ENSO Cycle: Recent Evolution, Current Status and Predictions

The following UPDATE is prepared by

Climate Prediction Center / NCEP –  23 November 2009

The latest weekly SST departures are:

• Niño 4   ~  1.5ºC
• Niño 3.4  ~  1.7ºC
• Niño 3 ~ 1.2ºC
• Niño 1+2 ~ 0.5ºC

El Niño Map. [SOURCE: NOAA/ Climate Prediction Center / NCEP]

SST Departures (°C) in the Tropical Pacific During the Last 4 Weeks
During the last 4-weeks, SSTs were at least 1.0°C above average across much of the equatorial Pacific and more than 2.0°C above average between 180°and 140°W. [Expanding across the Tropical Pacific. FEWW ]

[SOURCE: NOAA/ Climate Prediction Center / NCEP]

Global SST Departures (°C)
During the last four weeks, equatorial SSTs were above-average across the Pacific and Indian Oceans. Also, above-average SSTs covered large areas of the Northern Hemisphere subtropics.

[SOURCE: NOAA/ Climate Prediction Center / NCEP]

Weekly SST Departures (°C) for the Last Four Weeks

• During the last four weeks, positive equatorial SST anomalies persisted across the central and eastern Pacific Ocean.
• During the last 30 days, equatorial SST anomalies increased in some regions across the eastern half of the Pacific.

Upper-Ocean Conditions in the Eq. Pacific

• The basin-wide equatorial upper ocean (0-300 m) heat content is greatestprior to and during the early stages of a Pacific warm (El Niño) episode (compare top 2 panels) and leastprior to and during the early stages of a cold(La Niña) episode.
• The slope of the oceanic thermocline is least (greatest) during warm (cold) episodes.
• Recent values of the upper-ocean heat anomalies (positive) and the thermocline slope index (negative) reflect El Niño.

Sub-Surface Temperature Departures (°C) in the Equatorial Pacific

• During late September –mid November 2009, temperature anomalies at thermocline depth increased and expanded eastward across the central and east-central equatorial Pacific, in response to the downwelling phase of an oceanic Kelvin wave.
• The most recent period shows a continued eastward expansion of positive anomalies in the equatorial Pacific near 50 -150m depth.

Tropical OLR and Wind Anomalies During the Last 30 Days

Atmospheric Circulation over the North Pacific & North America During the Last 60 Day

Click image to enlarge.

Intraseasonal Variability

• Intraseasonal variability in the atmosphere (wind and pressure), which is often related to the Madden-Julian Oscillation (MJO), can significantly impact surface and subsurface conditions across the Pacific Ocean.
• Related to this activity
  • significant weakening of the low-level easterly winds usually initiates an eastward-propagating oceanic Kelvin wave.
  • Several Kelvin waves have occurred during the last year (see next slide).

Summary

• El Niño is present across the equatorial Pacific Ocean.
• Sea surface temperatures (SST) are at least 1.0ºC-2.0ºC above-average across much of the central and east-central equatorial Pacific.
• Based on current observations and dynamical model forecasts, El Niño is expected to continue to strengthen and last through at least the Northern Hemisphere winter 2009-10.

Information and images on this page are sourced from Climate Prediction Center/NCEP/NOAA. Edited by FEWW

Related Links:

• UK Flooding
• Speaking of El Niño, OLR Anomalies in Australia
• El Niño Update [16 Nov 2009]

• Recognizing El Niño
• El Niño and La Niña: Tracing the Dance of Ocean and Atmosphere
• TAO Diagrams
• El Niño Forecasts

El Niño Updates:

• El Niño Update [2 Nov 2009]
• El Niño [Main Page and Archive]