Coupled Ocean-Atmosphere Response to North Tropical Atlantic SST by pengtt

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									Coupled Ocean-Atmosphere Response to
   North Tropical Atlantic SST: Tropical
         Atlantic Dipole, NAO and ENSO
                   Lixin Wu
      Physical Oceanography Laboratory
          Ocean University of China
                Qingdao, China

 Collaborators: Feng He and Zhengyu Liu
              Center For Climatic Research,
              University of Wisconsin-Madison
Motivations




 Questions:
 (1)Are there anythings remaining elusive?
 (2)Are there anythings missing in this diagram
Atlantic-Tropical Pacific Teleconnection in
Recent Water-Hosing Experiments:
Dong and Sutton 2002         Zhang and Delworth 2005




 cooling


                warming
Questions:
Is tropical Atlantic dipole an internal
 dynamic mode?
How does the tropical Atlantic affect
 the extratropical North Atlantic,
 particular in different seasons?
How does the North Atlantic SST
 affect the tropical Pacific?
Outline
 Motivations
 Model and Experiments
 Tropical Atlantic Response
 Extratropical North Atlantic Response
 Tropical Pacific Response
 Summary and Conclusions
Model and Experiments

     Fast Ocean Atmosphere Model
               (FOAM)
 Atmosphere:
     CCM2 (dynamics) + CCM3 (physics)
     R15+19 levels (FOAM1.5)

 Ocean:
     MOM-like
     2.8ox1.4o x32 levels
Model Tropical
Climatology

    JJA




   DJF




   Annual
Coupled Modeling exploring:
Tropical Atlantic Response
MAM Wind and Heat Flux and SST   JAS Wind and Flux and SST
IV Approach   PC Approach
Forcing in the South Atlantic
                                MAM SST, Wind and Flux
Suggestions:
The tropical dipole mode is an
 internal coupled mode, with a
 maximum in Spring season
The coupled ocean-atmosphere
 interaction in the tropical Atlantic is
 controlled by the WES feedback and
 seasonal migration of the mean ITCZ
Extratropical North Atlantic Response
         Horseshoe

FMA              JJA
FMA              JJA




       Tripole

 OND
OND              FMA
                 FMA
FMA       MJJ
 FMA




   Z500
   Z500
OND       JFM
OND
North Tropical Atlantic can

 In late winter, force an NAO-like reponse in
  the extratropical Atlantic, and a dipole SST in
  the extratropics.
 In summer, force a northward Rossby
  wavetrain to Europe and a horseshoe-like SST
  pattern
 In the fall to next winter, force a NAO-like
  reponse (the sign as the previous winter) and
  a dipole
Tropical Pacific Response
FMA




JJA




OND
SST, surface wind, heat flux averaged over <10S,10N>
                                F
                          FMA
SST, SLP,wind,heat flux




 Z500, Precip.
Predictability


                 FM




                 JJA




                 OND
South Atlantic Forcing



                         FMA




                         JJA




                         OND
  Summary
Tropical Atlantic O/A interaction is regulated
 by WES feedback and seasonal migration of
 the ITCZ. The tropical Atlantic dipole is an
 internal dynamic mode, but occurs only in
 spring season.
Tropical Atlantic SST plays an important role
 in modulating extratropical Atlantic climate.
 NTA SST(late winter)->NAO->NTA SST(summer)
  ->horseshoe(summer and fall)
 ->NAO(next winter) ->extratropical dipole
The tropical north Atlantic SST can force a
 dipole-like SST in the eastern tropical Pacific,
 that can subsequently evolve into an ENSO-
 like pattern.
    Thank you

Physical Oceanography Lab.
 Ocean University of China
      Tsingdao, China

								
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