El Niño Monitoring and Prediction in JMA

1. El Niño Monitoring and Prediction in JMA Contents 1. What is El Niño ? 2. Evolution of 2002/03 El Nino 3. Current system for monitoring and prediction of El Niño in JMA 4. Current El Niño condition and outlook

2. What is El Nino ?

3. What is “El Niño” ? 　“The Boy” in Spanish = “The Chist child” ⇔“La Niña” = “The girl“ in Spanish （１）warm current each year around Christmas along the coast of Ecuador and Peru ： lasting only a few weeks to a month or more （２）condition warmer than normal in the eastern equatorial Pacific at intervals of several years: lasting about 12-18 months El Nino 1997/98 November 1997

4. Mean Sea Surface Temperature in equatorial Pacific January July April October • West > East throughout year, almost constant in West • Autumn = Annual minimun in East => Largest difference • Largely increase and reach peak in Spring

5. Mixed Layer (warm) Deep Water (cool) Upwelling Normal condition of the equatorial Pacific Low sea level pressure ascending motion High sea level pressure decending motion SST contribute to tropical rainfall and convective activity Walker Circulation Active Convection Warm water Westerly Easterly = Trade wind Heavy rain Equator Least rain Colder water up from deeper level to replace surface water Thermocline Deepest in the west Slopes upward the surface farther east From : NOAA homepage

6. SST in El Niño vs Normal Ｂ：Normal (November) Ａ：El Niño (November 1997) band of warm water were observed along the eq. Cooler water in East Ａ－Ｂ:Anomaly El Niño : Warmer than normal in the eastern equatorial Pacific

7. SST in La Nina vs Normal Ｂ：Normal (November) Ａ：La Niña (November 1988) Similar pattern as normal warmer than normal in west , cooler in east Ａ－Ｂ:Anomaly La Niña: Cooler than normal in the eastern equatorial Pacific

8. El Niño La Niña El Niño Monitoring Area （4S-4N,150W-90W） JMA’s definition The departure of the monitoring area SST from the1961-1990 average with five months running mean ・ above +0.5 C for six months or longer : El Niño ・ beneath –0.5 C for six months or longer : La Niña

9. El Nino Monitoring Area (Region B) （4S-4N,150W-90W） Sea Surface Temperature deviation from 1961-1990 mean （℃） 3 3 3 1982/83 La Nina 0 0 0 -3 -3 -3 1980 1985 （℃） El Nino 1995 1990 （℃） 1997/98 2000 El Nino / La Nina: ・develop every 2～7 years ・last for 12 months ～half a year 2005

10. Clearest sign = inverse relationship between of Psea at TAHITI and DARWIN DARWIN TAHITI Sea surface pressure anomaly at Darwin and Tahiti Sea surface pressure Southern Oscillation = Large-scale fluctuations in air pressure occurring between the western and eastern tropical Pacific High pressure at one site is almost always concurrent with low at other site Standeng wave Sea-saw = mass of air oscillation back and forth across the date line in tropics Pattern reverse every few years

11. Atmosphere Fluctuation in SST during ElNino and LaNina are accompanied by SO SOI ( Southern Oscillation Index ) : Trade Wind Strong weak Ocean Region B SST deviation from 1961-1990 mean warm cool El Nino Southern Oscillation (ENSO) Negative SO = D>T positive rB. Positive SO = D<T negative rB. = Oppsite phase El Nino and SO are deferent manifestation of single phenomenon

12. Atmosphere - ocean condition of El Nino Normal El Nino EQ From : NOAA homepage Weaken trade wind El Nino Walker Circulation is displaced Active convection area move eastward Warm water move eastward Upwelling weaken, gradient of thermocline reduced SST increase in the east

13. Outgoing Long-wave Radiation (OLR) El Nino (Nov. 1997) Small (large) value = active (inactive) convective activity Normal (1979-2000) Active Inactive

14. 850hPa Wind Weak Trade wind

15. Subsurface temperature along EQ in El Nino Subsurface temperature Normal Nov.97 Anomaly Sea surface temperature

16. Subsurface temperature along EQ in El Nino Anomaly Temperature Early stage (Jan97) Mature stage (Nov97) Latter stage (May98) Thermocline is where contour is crowed(green) Themocline is deeper than normal in western and central eq. Pacific = deep pool of warm ocean Depth of themocline reduce in western and central eq. Pacific and increase in East subsurface temp. increase in central and eastern Pacific Depth of themocline and subsurface temp. reduce throughout most of eq.

17. OHC (Ocean Heat Content) • = vertically averaged temperature in the top 260 m => depth of thermocline OHC anomaly OHC

18. Ocean and Atmosphere in Normal vs El Nino

19. Mature Stage of 1997/98 El Niño animation Sea Surface Temperature Ocean Temperature along Equator Ocean Subsurface changes lead to El Niño evolution

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39. EQ El Nino impact to the world climate • Tropics（Directly） • Eastward shift of convective precipitation • → Dry condition in the west and flood in the west • Indian monsoon precipitation less than normal (northern summer) Normal El Nino • Mid-latitude （Indirectly）

40. NO DATA NO DATA NO DATA Climate characteristics in ENSO Warm Events HotColdWet Dry World Climate in El Nino (December - February) （12 event in 1951～1996） Comvective precipitation area move eastward = Dryer in the central eq. Pacific, wetter in the western eq. Pacific Warm in almost the tropical region

41. Climate characteristics in ENSO Warm Events HotColdWet Dry World Climate in El Nino (June - August) （12 event in 1951～1996） Drier than normal in west and wetter in the central. Indian monsoon is weak increased heat over central and eastern eq. Pacific affect atmosphere circulation in subtropics and mid-latitude (ex. jet-stream move southward in boreal summer)

42. How does El Nino influence the climate in your country ?

43. El Niño and Climate in Japan Late End of theRainy Season (June - July) Cool Summer Warm Winter

44. Evolution of El Nino 2002/03

45. 4 seasons Time Series of Region A and Region B SST anomaly +1.4 C Nov. 02 • Compared with past events • 2002/03 El Nino: • Moderate in RegionB • Highest in Region A +1.2 C Nov. 02

46. SST anomaly in equatorial Pacific • Mar 2002 … negative anomalies were found in east and temporally positive anomalies off South America • Late May 2002… due to MJO (strong westerly wind), SST anomaly in East increase (> +1C appeared) • Nov 2002 … positive anomalies > +1C was widely found in the center and east. • Mar 2003 … negative anomalies appear in east and positive anomaly shrink in central. Mar.02 Nov.02 Mar.03

47. Subsurface Temperature anomaly Mar.02 • Mar 2002 …positive anomalies (occurred by MJO in Dec.01) reached coast of South America • July, August, October 2002… MJO induced eastward propagation of Kelvin wave. SST anomaly in East increase • Nov 2002 … negative anomalies spread in west and contrast between E and W was distinct. • Mar 2003 … positive anomalies shrank in east and negative anomalies partly appeared. Nov.02 Mar.03

48. OLR anomaly December. 2002 90W 120E 180 Consistent with ongoing El Nino Drier than normal : Indonesia, northern and eastern Australia Wetter than normal : central equatorial Pacific, southeast South America Only for 2 months

49. 2002/03 El Nino evolution along the equator (time-longitude cross section) OHC Anomaly SST Anomaly time mature

50. E W Madden-Julian Oscillation (MJO) • Tropical Intraseasonal Oscillation (20N-20S max.:EQ) • These fluctuations in tropical rainfall often go through an entire cycle in 30-60 days • => Assiciated global –scale, zonally oriented circulation cell propagated eastward • Convergence at low level • Easterly ot Westerly sometimes contribute to El Nino Africa Indonesia America Schematic diagram of lon-time structure of MJO