El Niño Southern Oscillation (ENSO) the Madden Julian Oscillation
and
Climate Forecasting
Dr. Wassila M. Thiaw Team Lead
International Desks Climate Prediction Center
National Oceanic and Atmospheric Administration
Acknowledgement: CPC ENSO Monitoring Team
What is ENSO?
ENSO Definition
• El Nino Southern Oscillation – Global coupled ocean-
atmosphere phenomenon that occurs in the tropical Pacific
• El Nino: The Little Boy, or Christ Child in Spanish, name given by fishermen off the coast of South America in the 1600s, with the appearance of episodic very warm water in the Pacific Ocean around December
• Ocean signature: El Niño, La Niña
– Major temperature fluctuations in surface waters
• Atmospheric signature: the Southern Oscillation (SO)
– Fluctuations in the air pressure difference between Tahiti and Darwin
• Ocean signature – atmospheric signature = ENSO
The ENSO Cycle
• Naturally occurring phenomenon
• Equatorial Pacific fluctuates between warmer-than-average (El Niño ) and colder-than-average (La Niña) conditions
• The changes in sea surface temperatures (SSTs) affect the
distribution of tropical rainfall and atmospheric circulation features (Southern Oscillation)
• Changes in intensity and position of jet streams (winds) and storm activity occur at higher latitudes.
• ENSO is associated with global impacts as a result of these adjustments in the tropical and extratropical circulation.
Sea Surface Temperature: Major Features
Atlantic Warm Pool
Pacific Warm Pool Equatorial Cold Tongues
Sea Surface Temperatures:
El Niño vs. La Niña
Equatorial cold
tongue is weaker than
average or absent during El Niño,
resulting in positive SST
anomalies
Equatorial cold
tongue is stronger than
average during La Niña,
resulting in
negative SST
anomalies
Precipitation:
El Niño vs. La Niña
Enhanced
rainfall occurs over warmer- than-average waters during El Niño.
Reduced
rainfall occurs over colder- than-average waters during La Niña.
El Nińo
La Nińa
SST Animation: 1997-1998
Normal
Normal Conditions:Winds and sea surface temperature are coupled: SSTs determine winds and vice versa
(1) The ocean thermocline is sloped upward towards the eastern Pacific. Easterly trade-winds help push warm water to the western Pacific and upwell cold water in the eastern Pacific Ocean.
(2) Warm water heats the atmosphere and makes it rise, so low- level trade winds blow towards warm water to fill the gap. Subsiding air occurs in the eastern basin.
Warm Cold
Pacific Ocean 3-D Schematic
Thermocline: Area of steep temperature difference between the shallower and the deeper waters of the ocean
El Nińo La Nińa Normal
The ENSO Cycle
El Nińo La Nińa
Low-Level Winds &
Thermocline Depth:
La Niña: stronger-than-average easterlies lead to a deeper
(shallower)-than-average thermocline in the western (eastern) eq. Pacific.
El Niño: weaker-than-average easterlies lead to a deeper
(shallower)-than-average thermocline in the eastern (western) eq. Pacific.
La Niña
• Thermocline becomes more shallow and the cold water upwelling increases in the eastern Pacific. .
• Easterly trade winds strengthen
• Convection becomes stronger over the far western Pacific Ocean/
Indonesia and more
suppressed in the central Pacific.
Warm Cold
El Niño
Warm
• Thermocline deepens and the cold water upwelling decreases in the eastern Pacific.
• Easterly trade winds weaken
• Convection shifts eastward over the central and/or eastern Pacific Ocean. Convection
becomes suppressed over the far western Pacific/ Indonesia.
Cold
Typical Evolution of the ENSO Cycle
• Irregular cycle with alternating periods of warm (El Niño) and cold (La Niña) conditions
• Events tend to occur every 2-7 years
• Strongest El Niño episodes appear to occur, on average, every 10-15 years
• Generally episodes form during the spring or summer, peak during the winter, and decay the following spring (invert
seasons for the Southern Hemisphere).
• La Niña episodes can last multiple years (1-3 years). Less common for El Niño, which last up to ~18months.
• Transitions from El Niño to La Niña tend to be more rapid
Pacific Ocean Recent Evolution - 2015
Measure of El Niño
The Equatorial Pacific Ocean is at the center of the ENSO phenomenon.
Nino 1+2: 10S – Eq; 80W – 90W Nino 3: 5S – 5N; 90W – 150W Nino 4: 5S – 5N; 150W – 160E Nino 3.4 5S – 5N; 120W – 170W
Pacific Ocean Recent Evolution - 2018
Measure of El Niño
Niño 4 0.3ᵒC Niño 3.4 0.2ᵒC Niño 3 0.2ᵒC
Niño 1+2 -1.0ᵒC
Measure of El Niño
Oceanic Nino Index (ONI), 1950 - Present
NOAA’s CPC primary index used to monitor ENSO Calculation: Running three-month average of SST anomalies in the Niño 3.4 region (5N-5S, 120W- 170W) are compared to a 30-year average
updated every 5 years. ONI is the observed difference from the average temperature.
Warm (red) and cold (blue) periods based on a threshold of +/- 0.5 degree C for the Oceanic Niño Index (ONI) periods updated every 5 years.
Periods of below and above normal SSTs are colored in blue and red when the threshold is met for a minimum of 5 consecutive overlapping seasons. The ONI is one measure of the El Niño-Southern Oscillation
Much of the predictability of the climate system
comes from sea surface temperature (SST) anomalies Especially in the tropics.
Why Monitor and Predict ENSO?
ENSO Teleconnections
EXAMPLE:
Eastward expansion of warm sea surface
temperatures during El Niño can result in an anomalous eastward shift of rainfall
(convection).
Enhanced thunderstorm activity in the central
Pacific will perturb the upper-level flow
resulting in suppression of rainfall over Indonesia Sustained warming of water over
the large tropical Pacific Ocean can lead to much above average rainfall in the tropical Pacific that in turn can influence the global circulation and rainfall in remote areas.
ENSO Teleconnections Oct-Dec - Precipitation
Gridded precipitation anomalies
(CPC Unified Precipitation associated with the standardized Nino 3.4 index From 1948 – 2010.
Linearity: regression anomalies show sign of El Nino reverse for La Nina
Nino 3.4 region:
equatorial Pacific 5N-5S; 120W – 165 W
ENSO Teleconnections Jul-Sep - Precipitation
Gridded precipitation anomalies
(CPC Unified Precipitation associated with the standardized Nino 3.4 index From 1948 – 2010.
Linearity: regression anomalies show sign of El Nino reverse for La Nina
Nino 3.4 region:
equatorial Pacific 5N-5S; 120W – 165 W
22
Skill in SST Anomaly Predictions
Predictions archived since 1997. The CFS shows a substantial increase in skill over the previous NCEP operational forecast model (CMP14) and comparable skill to operational statistical forecast models (CCA, CA, CONS, and MARKOV).
NOAA Official Probability ENSO Outlook
ENSO-neutral is favored through July-September 2018, with El Niño favored thereafter.
Chances for El Niño are near 65% during Northern Hemisphere winter 2018-19.
14 June 2018
ENSO Alert System: Types of Alerts
An El Niño or La Niña Watch:
Issued when the environment in the equatorial Pacific basin is favorable for the development of El Niño or La Niña conditions within the next six (6) months.
An El Niño or La Niña Advisory:
Issued when El Niño or La Niña conditions in the equatorial Pacific basin are observed and expected to continue.
Final El Niño or La Niña Advisory:
Issued after El Niño or La Niña conditions have ended.
No Alert:
The ENSO Alert System will not be active when El Niño or La Niña conditions are not observed or expected to develop in the
equatorial Pacific basin.
What triggers an ENSO Advisory?
El Niño conditions: one-month positive SST anomaly of +0.5 or greater in the Niño- 3.4 region and an expectation that the 3-month ONI threshold will be met.
La Niña conditions: one-month negative SST anomaly of −0.5 or less in the Niño- 3.4 region and an expectation that the 3-month ONI threshold will be met.
AND
An atmospheric response typically associated with El Niño/ La Niña over the equatorial Pacific Ocean.
The ENSO Alert System is based on El Niño and La Niña “conditions” that allows the NOAA Climate Prediction Center to be able to issue watches/
advisories in real-time.
Summary
• ENSO is a naturally occurring phenomenon
• Equatorial Pacific fluctuates between warmer-than-average (El Niño ) and colder-than-average (La Niña) conditions
• The changes in sea surface temperatures (SSTs) affect the
distribution of tropical rainfall and atmospheric circulation features (Southern Oscillation)
• Changes in intensity and position of jet streams (winds) and storm activity occur at higher latitudes.
• ENSO is associated with impacts on global rainfall as a result of these adjustments in the tropical and extratropical circulation.
CPC ENSO Updates
ENSO Alert System Status: Not Active.
http://www.cpc.ncep.noaa.gov/products/analysi s_monitoring/enso_advisory/ensodisc.pdf
The CPC weekly ENSO briefing is updated and posted on this web site:
http://www.cpc.noaa.gov/products/analysis_mon itoring/lanina/enso_evolution-status-fcsts-we
b.pdf
Monthly and Seasonal Climate Forecats
• Forecasts released by the 8th of each month
• All models have the same horizontal resolution 1.0◦ X 1.0◦
• Hindcasts are from 1982 - 2010
Models Initial Conditions Members
CFSv2 (NCEP) 1st to the 8th of month 32
CCMs (Canada) 1st of each month 20
GFDL 1st of each month 10
GFDL-FLOR 1st of each month 24
NASA /5dy 4mb / lstdy 7mb 11
NCAR 1st of each month 10
NMME Combined 107
North America Multimodel Model Ensemble Overview
http://www.cpc.ncep.noaa.gov/products/international/nmme/ensm/index.shtml
Regionalized NMME Forecasts
Deterministic Probabilistic
• Bias-corrected ensemble mean
anomalies: anomalies are calculated using model’s climatology
• MME uses equal weighting for each model
• Skill measures: AC; RMSE
• For each year, tercile (A, N, B)
thresholds determined from 28 years of the hindcasts of individual models
• Forecast mbers assigned to terciles; # of mbers in each class counted
• Historical skill used to calibrate probability forecasts.
Deterministic vs. Probabilistic Forecast
The Madden Julian Oscillation (MJO)
MJO Characteristics
The MJO is an intraseasonal wave originating in the Tropics
The MJO results in changes in atmospheric and oceanic conditions
• Lower- and upper-level wind
• Cloudiness and tropical rainfall
• Sea level Pressure
• Sea surface temperature (SST)
• Ocean surface evaporation
• Ocean chlorophyll
Typical period of the MJO cycle is approximately 30-60 days
Acts on a global spatial scale
Coherent eastward propagation (EH 5 m/s and WH 15 m/s)
Madden and Julian, 1971; 1972; Zhang, 2005; Hendon and Salby, 1994
Green areas
Increased rainfall
Enhanced phase of the MJO
Brown areas
Decreased rainfall
Suppressed phase of the MJO
Composite of the MJO Lifecycle
Tropical Rainfall
MJO Index
The axes (RMM1 and RMM2) represent daily values of the PCs from two modes
The triangular areas indicate the location of the MJO enhanced convective phase
Counter-clockwise motion is indicative of eastward propagation. Large dot most recent day.
Distance from center proportional to strength
Line colors distinguish different months Weak
MJO
Strong MJO
Wheeler and Hendon, 2004
--EOF analysis (OLR, 850 and 200 hPa zonal wind) --Index uses information from first two modes
MJO Impacts – Tropical Rainfall Hotspots
Boreal Summer
Boreal Winter Boreal Summer
CPC MJO Weekly Update
--Review of weekly changes in the MJO --Includes some of the monitoring and prediction products described here
--Provides an assessment in compact form
--Anticipated evolution and impacts of the MJO during the next 1-2 weeks
--Released every Monday ~ 4 PM ET
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjoupdate.pdf
Global Tropics Hazards and Benefits Outlook
• State of the MJO
• Much emphasis is given to the state of the MJO and its projected phases on the Wheeler-Hendon diagram at the moment of the forecasts.
• Refer to the MJO monitoring and prediction tools to determine if an active MJO is present
http
://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO /CLIVAR/clivar_wh.shtml
#
Sub-seasonal Forecasts
• MJO is present and projected to remain active through the outlook period:
– MJO based rainfall anomaly composites for guidelines as to where to draw wet or dry polygons
• NWP outputs to ensure consistency between the rainfall anomaly MJO composites and the NWP guidance
• High confidence in the forecasts when the MJO composites are in strong agreement with the NWP.
• If there are discrepancies, a careful look at the NWP outputs is warranted and use of intuition and experience will guide the forecaster’s decision.
Sub-seasonal Forecasts
Week1 and Week 2 Outlook
CPC International Desks Resources
Main website
http://www.cpc.ncep.noaa.gov/products/international/index.shtml Africa
http://www.cpc.ncep.noaa.gov/products/international/africa/africa.shtml Central Asia
http://www.cpc.ncep.noaa.gov/products/international/casia/casia.shtml Central America
http://www.cpc.ncep.noaa.gov/products/international/camerica/camerica.shtml South Asia
http://www.cpc.ncep.noaa.gov/products/international/sasia/sasia.shtml NMME Monthly and Seasonal Forecasts
http://www.cpc.ncep.noaa.gov/products/international/nmme/nmme.shtml NCEP GFS and GEFS Weather and Sub-seaonal Forecasts
http://www.cpc.ncep.noaa.gov/products/international/cpci/data/africa_region.shtml
Summary
• CPC is the government agency with mandate to provide access to real time climate forecasts for the U.S. from week-2 to monthly and seasonal time scales
• CPC’s International Desks provide access to global weather and climate forecasts in support of the U.S. mission abroad.
• Activities include climate monitoring and forecasting to support hazards outlooks for food security, and maintaining the website
• Work underway to expand portfolio to include climate and health
