Contents 1. What is El Niño ? 2. Evolution of 2002/03 El Nino
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Transcript of Contents 1. What is El Niño ? 2. Evolution of 2002/03 El Nino
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
El Niño Monitoring and Prediction in JMA
El Niño Monitoring and Prediction in JMA
What is El Nino ?
November 1997November 1997
El Nino 1997/98
What is “El Niño” ?
(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
⇔ “ La Niña” = “The girl“ in Spanish
“ The Boy” in Spanish = “The Chist child”
Mean Sea Surface Temperature in equatorial Pacific
January
April
July
October
1. West > East throughout year, almost constant in West
2. Autumn = Annual minimun in East => Largest difference
3. Largely increase and reach peak in Spring
Normal condition of the equatorial Pacific
Easterly= Trade wind
Active Convection
Thermocline
Mixed Layer(warm)Deep Water(cool)
Upwelling
From : NOAA homepage
Equator
Warm water
Walker Circulation
SST contribute to tropical rainfall and convective
activity
Westerly
Low sea level pressure ascending motion
High sea level pressure decending motion
Colder water up from deeper level to replace surface water
Slopes upward the surface farther east
Deepest in the west
Heavy rain
Least rain
B: Normal (November)A: El Niño (November 1997)
A-B :Anomaly
SST in El Niño vs NormalSST in El Niño vs Normal
El Niño :
Warmer than normal in the eastern equatorial Pacific
band of warm water were
observed along the eq. Cooler water in East
B: Normal (November)A: La Niña (November 1988)
A-B :Anomaly
SST in La Nina vs NormalSST in La Nina vs Normal
La Niña :
Cooler than normal in the eastern equatorial Pacific
Similar pattern as normal warmer than normal in west , cooler in east
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
El Niño La Niña
Sea Surface Temperature deviation from 1961-1990 mean
1980
1990
2000
1985
1995
0
-3
3
0
-3
3
0
-3
3
(℃)
(℃)
(℃)
El Nino Monitoring Area (Region B)
( 4S-4N,150W-90W )
El Nino
La Nina
2005
1997/98
1982/83
El Nino / La Nina:・ develop every 2 ~7 years・ last for 12 months ~ half a year
Southern Oscillation
= Large-scale fluctuations in air pressure occurring between the western and eastern tropical Pacific
Sea
surf
ace
pres
sure
Sea surface pressure anomaly at Darwin and Tahiti
DARWIN TAHITI
Clearest sign = inverse relationship between of Psea at TAHITI and DARWIN
Standeng wave
Sea-saw = mass of air oscillation back and forth across the date line in t
ropics
Pattern reverse every few
years
High pressure at one site is almost always concurrent with low at
other site
SOI ( Southern Oscillation Index ) : Trade Wind
Strong
weak
AtmosphereAtmosphere
warm
cool
OceanOcean Region B SST deviation from 1961-1990 mean
El Nino Southern Oscillation (ENSO)
Fluctuation in SST during ElNino and LaNina are accompanied by S
O
Negative SO = D>T positive rB. Positive SO = D<T negative rB. = Oppsite phase
El Nino and SO are deferent manifestation of single phen
omenon
Atmosphere - ocean condition of El Nino
Weaken trade wind
Warm water move eastward
SST increase in the east
Active convection area move eastward
From : NOAA homepage
Normal El Nino
EQ
El Nino Walker Circulation is displaced
Upwelling weaken, gradient of thermocline reduced
Outgoing Long-wave Radiation (OLR)
El Nino (Nov. 1997)
Normal (1979-2000)
ActiveInactive
Small (large) value = active (inactive) convective activity
850hPa Wind
Weak Trade wind
Subsurface temperature along EQ in El Nino
Nov.97
Normal
Anomaly
Sea surface temperature Subsurface temperature
Subsurface temperature along EQ in El NinoTemperature
Early stage (Jan97)
Mature stage (Nov97)
Latter stage (May98)
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 c
entral and eastern Pacific
Depth of themocline and subsurface temp. reduce thr
oughout most of eq.
Thermocline is where contour is crowed (green)Anomaly
OHC anomaly
OHC (Ocean Heat Content)
= vertically averaged temperature in the top 260 m => depth of thermoclineOHC
Ocean and Atmosphere in Normal vs El Nino
Normal El Nino
SST Warm in West Cool in East
Increase in East
convective precipitation
western Pacific
Move to central Pacific
Trade wind Strong (easterly)
weak
Walker Circulation
Over western Pacific
Displaced eastward
Warm water Deep in West Move eastward
Thermocline Slant from East to West
Reduced gradient
Mature Stage of 1997/98 El NiñoNiño
Sea Surface Temperature
Ocean Temperature along Equator
Ocean Subsurface changes lead to El Niño evolutionNiño evolution
animation
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•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)
•Mid-latitude ( Indirectly )
El Nino impact to the world climate
EQ
Normal El Nino
Climate characteristics in ENSO Warm Events
Hot Cold Wet Dry
NO DATA
NO DATA
NO
DATA
World Climate in El Nino (December - February)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
( 12 event in 1951 ~ 1996 )World Climate in El Nino (June - August)World Climate in El Nino (June - August)
Climate characteristics in ENSO Warm Events Hot Cold Wet Dry
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 su
btropics and mid-latitude (ex. jet-stream move southward in boreal summer)
How does El Nino influence the climate in your country ?
El Niño and Climate in JapanEl Niño and Climate in Japan
0% 20% 40% 60% 80% 100%Oki nawa
Kyushu
Shi koku
Chugoku
Kantou
Touhoku
Earl y
Normal
Late
0% 20% 40% 60% 80% 100%
Oki nawa
Wast J apan
East J apan
North J apanLowNormalHi gh
Late End of the Rainy Season (June - July)
Cool Summer
Warm Winter
Evolution of El Nino 2002/03
Time Series of Region A and Region B SST anomaly
+1.4 CNov. 02
+1.2 CNov. 02
Compared with past events
2002/03 El Nino:
• Moderate in RegionB
•Highest in Region A
4 seasons
Mar.02
Nov.02
Mar.03
SST anomaly in equatorial PacificSST 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
Subsurface Temperature anomalySubsurface Temperature anomaly
•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.
Consistent with ongoing El Nino
Drier than normal : Indonesia, northern and eastern Australia
Wetter than normal : central equatorial Pacific, southeast South America
OLR anomalyOLR anomaly
December. 2002180120E 90W
Only for 2 months
time
2002/03 El Nino evolution along the equator
OHC Anomaly SST Anomaly
(time-longitude cross section)
mature
Africa Indonesia America
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
Schematic diagram of lon-time structure of MJO
time
2002/03 El Nino evolution along the equator
OHC Anomaly
(time-longitude cross section)
Westerly burst associated with MJO induced eastward propagation of
Kelvin wave
U850 Anomaly
2002/03 (SON) composite (SON)
SST anomaly
OHC anomaly
SST: 72,76,82,86,91,97
OHC: 86,91,93,97
El Nino 2002/03 vs Composite map
2002/03 warmer in Central and cooler than Eastern
Current system for monitoring and prediction of El Niño in JMA
Ocean DataAssimilation
System (ODAS)
Coupled AtmosphereOcean General Circulation
Model
Ocean Initial Cond. NINO.3 SST Anomaly
SST XBT TAO/TRITON
Sea Surface Height
Wind Stress Heat and Water Fluxes
Model Output Statistics(MOS)
Analysis of latestatmosphere-ocean
conditions
Official SST Forecast
・ El Nino Monitoring Report ・ “ El Nino Monitoring and Outlook” (WMO/DDB & TCC) ・ Climate Monitoring Report・ Monthly Ocean Report
JMA EL NIÑO MONITORING AND PREDICTION SYSTEM
Observation
El Niño
Monitoring
El Niño
PredictionPublic Announcement
Atmos. Initial Cond.Argo
DynamicalSeasonalForecast
Atmospheric GCM
Ocean GCM
Coupled
GCM
New E l Niño Forecast Model (JMA-CGCM02)
Flux Adjustment One Day Coupling
Ocean Data Assimilation System
Initiali- zation
Data Assimilation System
7 Months Forecast
MOS Corrected NINO3 SSTA
・ T42L40・ Arakawa-Schubert・ SiB
・ 2.5 x 0.5 ~ 2.0 L21・ Bryan-Cox type・ Closure Mixing
T213 L40
Observed Temp, Salinity, Sea Level Height
IAU (Incremental Analysis Update)
LAF, 6 initials
3 DVAR
Since July 2003
Assimilated data
Run twice a month
( 1988Feb-2000Jan, 96exps. )ACC RMSE
ReginB(NINO3)
ReginD(NINO.WEST)
Cgcm02 is higher than Cgcm01 especially up to 5-9 months
Cgcm02 is smaller than Cgcm01
Skill of Region B is better than that of Region D
Predictor: Initial B SST OHC (6S, Eq,6N) Zonal Wind Stress (Eq) SST (Eq) Forecast B SST OHC (6S, Eq,6N) Zonal Wind Stress (Eq) SST (Eq) Lead time Calendar month
Predictand: Regin B (Nino 3) SST
MOS: Stepwise Regression Analysis
②OHC (160E,6N)
① B SST
Choose 11/73 predictor
Gravest contributor
A C
C
Lead Time ( month)
RM
SE
()
℃
ACC (CGCM) ACC (MOS)
RMSE (CGCM) RMSE (MOS)
Region B SST Skill ACC
MOS remain above 0.8 until 9 months lead time
RMSE
MOS reduce and remain 0.5C up to 8 months lead time
Calculated from 96 hindcast
experiments (1988- )
Before & after MOS correction
El Nino product on TCC Homepage
El NiEl Niñño Information of JMAo Information of JMA
• WMO Distributed Data Bases (http://ddb.kishou.go.jp)
• Tokyo Climate Center HP (http://okdk.kishou.go.jp)
Main changes :Addition of Summary
Enhancement of Atmosphere ComponentOLR Index (OLR-DL, U200-CP, U850-CP)200hPa velocity potential anomaly850hPa zonal wind anomaly
Renewal of TCC Homepage !Renewal of TCC Homepage ! December 2003 December 2003 ~~
We recommend JMA El Nino Product, because ...
ADIOS A EL NIÑO, HOLA A LA NIÑA
May 19, 2003 — On the heels of El Niño’s departure the world could soon be facing the return of La Niña say scientists at NOAA. Based on current sea surface temperatures and recent atmospheric and oceanic trends in the tropical Pacific, it is likely that La Niña will develop over the next few months…….
Press release of NOAA
After that, how did the equatorial Pacific SST Anomalies change ?
•During May to June, a temporary cooling was found in the east.
• In the late September to October, positive anomalies appeared across the central and eastern equatorial Pacific.
NO La Nina !!Shall we get El Nino products
from many sources ?
El Nino 2002/03
Current Diagnosis and Outlook
Sea Surface Temperature (October 2003)Current Diagnosis
RegionB
+0.2 (S) => +0.6(O)
Sub Surface Temperature (October 2003)Current Diagnosis
El Nino Outlook (Nov. 2003 – May 2003)
The Region B (Nino 3) SST is likely to be around normal in this autumn and winter.
It will possibly be slightly warmer than normal afterwards until May 2004.
SummarySummary
• El Nino Southern Oscillation (ENSO) is a interannual climate variation of the ocean-atmosphere system in the tropical Pacific.
• Each El Nino/La Nina event is different.
• Would you check the El Nino product of TCC Homepage, always or sometime ?
Thank you
Monthly El Niño Monitoring Report
Ocean Data Assimilation System
El Niño Forecasting model(Atmosphere and Ocean Coupled Model)
Global Ocean Surface and Subsurface Data
Long- range Forecast of Japan
Every day
Twice a month
JMA EL NIÑO MONITORING AND PREDICTION SYSTEMJMA EL NIÑO MONITORING AND PREDICTION SYSTEM
Subsurface observation Subsurface observation datadata (( September.2003September.2003 ))
:70 buoys
Observation is insufficient
Data Assimilation
SST Monitoring in Regions A-D
Region A: 4N-4S, 160E-150W
Region B: 4N-4S, 150W-90W
Region C: EQ-10S, 90W-80W
Region D: 14N-EQ,, 130E-150E