presented by andrew wittenberg geophysical fluid dynamics laboratory 17 october 2012
DESCRIPTION
Tropical Climate Change and ENSO. Presented by Andrew Wittenberg Geophysical Fluid Dynamics Laboratory 17 October 2012. NOAA GOES-11 5 Oct 2011 1800 UTC. The Tropics: Firebox of the global circulation. Thompson Higher Education. 2. Projected surface temperature changes. - PowerPoint PPT PresentationTRANSCRIPT
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Geophysical Fluid Dynamics Laboratory
Presented byAndrew Wittenberg
Geophysical Fluid Dynamics Laboratory17 October 2012
Tropical Climate Change and ENSO
NOAAGOES-11
5 Oct 20111800 UTC
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Geophysical Fluid Dynamics Laboratory
The Tropics: Firebox of the global circulation
2
ThompsonHigher Education
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Geophysical Fluid Dynamics Laboratory
Projected surface temperature changes
3
Strongest warmingover land &
equatorial Pacific
More warmingin calm areas,
and wherewinds weaken
Feedbacks fromlow clouds &
ocean advection
Vecchi et al. (2008)Vecchi & Wittenberg
(2010)Collins et al. (2010)
Xie et al. (2010)
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Geophysical Fluid Dynamics Laboratory
Projected water vapor changes
4
Warming pumpswater vapor intothe atmosphere
Vecchi & Wittenberg (2010)
Collins et al. (2010)Xie et al. (2010)
Tropics today:~40 kg of water vapor
2050: +4 kg
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Geophysical Fluid Dynamics Laboratory
Projected rainfall changes
5
Broadly:“the wet get wetter,the dry get drier”.
Over tropicaloceans:
“the warmerget wetter”.
Held & Soden (2006)Vecchi & Wittenberg (2010)
DiNezio et al. (2010)Xie et al. (2010)
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Geophysical Fluid Dynamics Laboratory
Projected tropospheric temperature changes
6
Increasedstatic stabilityof atmosphere
Helps expandHadley Cell
Weakensconvective
mass fluxes &trade winds
Held & Soden (2006)Vecchi et al. (2006)
Frierson et al. (2007)Collins et al. (2010)
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Geophysical Fluid Dynamics Laboratory
Projected upper-ocean temperature changes
7
Tropical oceanmore stratified
Stronger,shallower, and
flatter equatorialthermocline
DiNezio et al.(JC 2009, EOS 2010)Collins et al. (2010)
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Geophysical Fluid Dynamics Laboratory
Earth's dominant interannual climate fluctuation
8
NOAA/CPC
El Niño
Normal
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Geophysical Fluid Dynamics Laboratory
Projected ENSO changes (CMIP3/AR4)
9
correl(SST trend of 1%/yr, SST.PC1 of PICTRL)10S-10N, 120E-80W
Yamaguchi & Noda (JMSJ 2006)
std(S
LP.P
C1
of
SR
ES.A
2 (
20
51
-21
00
))/
std(S
LP.P
C1
of
20
C3
M)
30
S-3
0N
, 3
0E-6
0W
van O
ldenborg
h e
t al. (
OS 2
00
5)
CM2.1
Weak/ambiguousnear-term
anthropogenicimpacts on ENSO
Intrinsicmodulation
Reviews:
Meehl et al.(IPCC-AR4 2007)
Guilyardi et al.(BAMS 2009)
Vecchi & Wittenberg (WIREs CC 2010)
Collins et al.(Nature Geosci. 2010)
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Geophysical Fluid Dynamics Laboratory
Intrinsic modulation of ENSO: Observed
10
Vecchi & Wittenberg(WIREs CC 2010)
Historical SSTA (ERSST.v3)
Palmyra corals(Cobb et al.,
Nature 2003)
Multiproxy reconstructions:Emile-Geay et al.(2011abc, subm.)
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Geophysical Fluid Dynamics Laboratory
Intrinsic modulation of ENSO: Simulated
11
Wittenberg (GRL 2009)
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Geophysical Fluid Dynamics Laboratory
The most extreme ENSO epochs
12
Wittenberg et al.(in prep.)
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Geophysical Fluid Dynamics Laboratory
Initial conditions for “perfect” reforecasts
13
Wittenberg et al.(in prep.)
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Geophysical Fluid Dynamics Laboratory
40 “perfect” reforecasts – best possible skill
14
Wittenberg et al.(in prep.)
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Geophysical Fluid Dynamics Laboratory
1860: Spread of 100yr NINO3 SST spectra
15
286 ppmv
Wittenberg (2009)
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Geophysical Fluid Dynamics Laboratory
1990: Stronger annual cycle & ENSO
16
353 ppmv
Wittenberg (2009)
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Geophysical Fluid Dynamics Laboratory
2xCO2: A perfect climate for ENSO?
17
572 ppmv
Wittenberg (2009)
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Geophysical Fluid Dynamics Laboratory
4xCO2: Stronger annual cycle, weaker ENSO
18
1144 ppmv
Wittenberg (2009)
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Geophysical Fluid Dynamics Laboratory
Competing changes in ENSO feedbacks
19
1. Amplifiers - stronger rainfall & wind stress responses to SSTAs - stronger thermocline, shallower mixed layer - weaker replenishment of surface waters from below
2. Dampers - stronger evaporative & cloud-shading responses - weaker upwelling -> surface less connected to thermocline - smaller dynamic warm pool -> less room for warming
3. Ambiguous effects - stronger intraseasonal wind variability
Guilyardi et al. (BAMS 2009); Vecchi & Wittenberg (WIREs CC 2010)Collins et al. (Nature Geosci. 2010); DiNezio et al. (JC 2009; EOS 2010; JC 2011 subm.)
Ongoing activities with CLIVAR Working Groups,D. Battisti, A. Atwood, M. Cane, C. Karamperidou, F.-F. Jin, J. Brown, F. Graham
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Geophysical Fluid Dynamics Laboratory
Summary
20
1. Projections of tropical climate change - tropics moisten, stratify, expand - circulation weakens; ocean thermocline shoals & flattens - SST: calm(er) get warmer; ocean advection changes - rainfall: wet get wetter; warmer get wetter - distinct from El Niño
2. Is ENSO changing? - diverse projections - competing feedbacks + optima + model biases -> uncertainty
3. Risk of intrinsic ENSO modulation - ENSO capable of wide swings in behavior on its own - interannual predictability only, except after a big event