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El Niño Southern Oscillation (ENSO) the Madden Julian Oscillation and Climate Forecasting

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.

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El Niño Southern Oscillation (ENSO) the Madden Julian Oscillation and Climate Forecasting

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  1. El Niño Southern Oscillation (ENSO)the Madden Julian OscillationandClimate Forecasting Dr. Wassila M. Thiaw Team Lead International Desks Climate Prediction Center National Oceanic and Atmospheric Administration Acknowledgement: CPC ENSO Monitoring Team

  2. What is ENSO?

  3. 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

  4. 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.

  5. Sea Surface Temperature: Major Features Atlantic Warm Pool Pacific Warm Pool Equatorial Cold Tongues

  6. Sea Surface Temperatures:El Niño vs. La Niña Equatorial cold tongue is stronger than average during La Niña, resulting in negative SST anomalies Equatorial cold tongue is weaker than average or absent during El Niño, resulting in positive SST anomalies

  7. Precipitation:El Niño vs. La Niña Enhanced rainfall occurs over warmer-than-average waters during El Niño. El Nińo Reduced rainfall occurs over colder-than-average waters during La Niña. La Nińa

  8. SST Animation: 1997-1998

  9. Pacific Ocean 3-D Schematic 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. Warm Cold (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. Thermocline: Area of steep temperature difference between the shallower and the deeper waters of the ocean

  10. The ENSO Cycle Normal El NińoLa Nińa

  11. Low-Level Winds & Thermocline Depth: El NińoLa Nińa El Niño: weaker-than-average easterlies lead to a deeper (shallower)-than-average thermocline in the eastern (western) eq. Pacific. La Niña: stronger-than-average easterlies lead to a deeper (shallower)-than-average thermocline in the western (eastern) eq. Pacific.

  12. La Niña • Convection becomes stronger over the far western Pacific Ocean/ Indonesia and more suppressed in the central Pacific. Warm Cold • Thermocline becomes more shallow and the cold water upwelling increases in the eastern Pacific. . • Easterly trade winds strengthen

  13. El Niño • Convection shifts eastward over the central and/or eastern Pacific Ocean. Convection becomes suppressed over the far western Pacific/ Indonesia. Warm Cold • Thermocline deepens and the cold water upwelling decreases in the eastern Pacific. • Easterly trade winds weaken

  14. 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

  15. Measure of El Niño Pacific Ocean Recent Evolution - 2015 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

  16. Measure of El Niño Pacific Ocean Recent Evolution - 2018 Niño 4 0.3ᵒC Niño 3.4 0.2ᵒC Niño 3 0.2ᵒC Niño 1+2 -1.0ᵒC

  17. 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

  18. Why Monitor and Predict ENSO? Much of the predictability of the climate system comes from sea surface temperature (SST) anomalies Especially in the tropics.

  19. 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.

  20. 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

  21. 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). 22

  23. NOAA Official Probability ENSO Outlook 14 June 2018 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.

  24. 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.

  25. What triggers an ENSO Advisory? The ENSO Alert System is based onEl Niño and La Niña “conditions” that allows the NOAA Climate Prediction Center to be able to issue watches/ advisories in real-time. 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.

  26. 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.

  27. CPC ENSO Updates ENSO Alert System Status: Not Active.  http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.pdfThe CPC weekly ENSO briefing is updated and posted on this web site:http://www.cpc.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

  28. Monthly and Seasonal Climate Forecats

  29. North America Multimodel Model Ensemble Overview • 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

  30. Regionalized NMME Forecasts http://www.cpc.ncep.noaa.gov/products/international/nmme/ensm/index.shtml

  31. Deterministic vs. Probabilistic Forecast 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 mbersin each class counted • Historical skill used to calibrate probability forecasts.

  32. The Madden Julian Oscillation (MJO)

  33. 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

  34. Composite of the MJO Lifecycle Tropical Rainfall Green areas Increased rainfall Enhanced phase of the MJO Brown areas Decreased rainfall Suppressed phase of the MJO

  35. 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 --EOF analysis (OLR, 850 and 200 hPa zonal wind) --Index uses information from first two modes Wheeler and Hendon, 2004

  36. MJO Impacts – Tropical Rainfall Hotspots Boreal Summer Boreal Winter Boreal Summer

  37. CPC MJO Weekly Update http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjoupdate.pdf --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

  38. Global Tropics Hazards and Benefits Outlook

  39. Sub-seasonal Forecasts • 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#

  40. 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.

  41. Week1 and Week 2 Outlook

  42. 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

  43. 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

  44. Thank youwassila.thiaw@noaa.gov

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