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Seasonal to Interannual Climate Variability in the21st and 22nd Century: ENSO & NAO
Overview ENSO NAO ENSO&NAO Summary
ElNiño/Southern Oscillation (ENSO)North Atlantic Oscillation (NAO)ENSO&NAOSummary&Discussion
Overview ENSO NAO ENSO&NAO Summary
Modell & Data:ECHAM5/MPIOM (IPCC runs)
20th century simulations 1900-2000 (20C)A1B scenarios 2001-2100 (21C)A1B scenario stabilisation runs 2101-2200 (22C)--> 3 realisations each
ObservationsRe-Analysis (ERA40, NCEP)
Overview ENSO NAO ENSO&NAO Summary
Coupling Atmosphere and Ocean
ElNinoSea SurfaceTemperature
Southern OscillationSea Level Pressure
Overview ENSO NAO ENSO&NAO Summary
1982 19901986 1994 1998 2002 2006
Nino3.4 IndexSSTa[x=150W:90W, y=5S:5N]
Frequency 2-7yEl Nino period typically last 1y, max. Winter
Overview ENSO NAO ENSO&NAO Summary
Nino3.4 IndexSSTa[x=150W:90W, y=5S:5N]
1982 19901986 1994 1998 2002 2006
Frequency 2-7yEl Nino period typically last 1y, max. WinterLa Nina period >= 1y
Overview ENSO NAO ENSO&NAO Summary
Impact I: DroughtAnnually Averaged 06.1998 – 05.2002
[mm/y][ºC]
-1 1 200 200
Hoerling and Kumar 2003
Overview ENSO NAO ENSO&NAO Summary
Impact II: HurricaneStorm Tracks
(From IRI)
Overview ENSO NAO ENSO&NAO Summary
Impact II: HurricaneStorm Tracks
Others Fields of Impact:Human HealthWater RecourcesNatural HazardsEnergyEcosystemswww.columbia.edu/climate/ENSO/societal
(From IRI)
Overview ENSO NAO ENSO&NAO Summary
Winter (DJF) Nino3.4 index(IPCC runs)
Relative to control simulationMean shift towards higher valuesIncrease in variability (detrendedNino3.4 index)
σ20C=1.62σ21C=1.81σ22C=1.91
Red: ERA40Black/Grey : ECHAM5/MPIOM
20C
21C
22C
Overview ENSO NAO ENSO&NAO Summary
22C
20C
ENSO Impact on Surface Temperature (IPCCruns):
Composites: ENSO+ – ENSO– whereENSO+ (ENSO–) defined as Nino3.4 Index > 1sd (<–1sd)
Fields (Index) relative to the period considered
Fields (Index) detrended prior analysis
5
-5
5
-5
Overview ENSO NAO ENSO&NAO Summary
Positive Phase:Strong Gradient of High & Low Pressure in the North AtlanticEnhanced Storm Activity along„northern“ routeAssociated wet (dry) conditionsand more (less) precipitation in Northern (Southern) Europe
Lahmont-Doherty Earth Observatory
Overview ENSO NAO ENSO&NAO Summary
Negative Phase:Weak Gradient of High & Low Pressure in the North AtlanticEnhanced Storm Activity along„southern“ routeAssociated wet (dry) conditionsand more (less) precipitation in Southern (Northern) Europe
Lahmont-Doherty Earth Observatory
Overview ENSO NAO ENSO&NAO Summary
Winter NAO Index
-2
-1
1
2
0
1880 1900 1920 1940 1960 1980 2000
Overview ENSO NAO ENSO&NAO Summary
Averaged WinterTemperature overNorthern Europe (50ºN-70ºN ;0ºE-60ºE)
1880 1900 1920 1940 1960 1980 2000
-4
-2
2
4
0[°C
]
NAO Impact:Near Surface Temperature
2
1
0
-1
-2
1960 1980 2000
Overview ENSO NAO ENSO&NAO Summary
Appenzeller et al. 2001
-2
-1
1
2
0
Overview ENSO NAO ENSO&NAO Summary
Appenzeller et al. 2001
Other fields of impact:
Ecosystems (Marine,Terrestrial,Freshwater)
Energy...
J. W. Hurrell et al. „The North Atlantic Oscillation:Climatic Significance andEnvironmental Impact“
Overview ENSO NAO ENSO&NAO Summary
Winter NAO index(IPCC runs)
Regressed onto 1. EOF of controlsimulationSlight mean shift towards higherValues
ō22C=0.31Small increase in variability(detrended)
σ20C=1.00σ21C=1.08σ22C=1.13
Red: ERA40Black/Grey : ECHAM5/MPIOM
20C
21C
22C
Overview ENSO NAO ENSO&NAO Summary
Averaged Northern Europe Winter Temperature(IPCC runs)
20C 21C 22C
NAO Index > 1sdNAO Index < –1sd
[ºC] [ºC] [ºC]
Overview ENSO NAO ENSO&NAO Summary
Composites of Geopotential 500hPaElNino – Climatology (IPCC runs)
20C 21C 22C
Contour Levels 10 gpm
Overview ENSO NAO ENSO&NAO Summary
Composites of Geopotential 500hPaLaNina – Climatology (IPCC runs)
20C 21C 22C
Contour Levels 10 gpm
Overview ENSO NAO ENSO&NAO Summary
Winter NAO index(IPCC runs)
20C-0.13<r<-0.01
21C-0.30<r<-0.26
22C-0.46<r<-0.37
Nino3.4 Index > 1sdNino3.4 Index < –1sd
Mueller and Roeckner 2005
Overview ENSO NAO ENSO&NAO Summary
Variability of today‘s ENSO and NAO have a relatively large impact on local climate (even in remote regions)
Mean State and Variability of future ENSO is increased, but relatively modest for the NAO (as suggested by theECHAM5/MPIOM IPCC scenarios)
Variability of existing patterns of impact with respect to ENSO and the NAO are likely to be increased in the21st/22nd century
ENSO and NAO are increasingly correlated in the 21st/22nd
century
Overview ENSO NAO ENSO&NAO Summary
A more precise formulation of the results requires to include several sources of uncertaintiesModel formulation (i.e. multi-model approach)Anthropogenic Greenhouse Gas Forcing (B1 ...)-> EU-Project ENSEMBLESDecadal Climate Variability
Given a high forecast skill of ENSO several seasons aheadand assuming a stronger relationship between ENSO& NAO, what are the implications for long-range (seasonal)forecasting in the sphere of the NAO
The End