CT1/CT3 Meeting 22-23 April 2013 Hamburg

Predictability associated with the Atlantic ocean SST variability

G. Gastineau, J. Garcia-Serrano, C. Frankignoul

Introduction

• Atlantic ocean SST variability : AMO + North Atlantic Horseshoe

• Are both pattern related? What are their influence on the European/American climate?

Data and methods

Data : • Atmosphere : 20CR-NOAA reanalysis (56 members)• SST : HadISST

Global warming influence removed :• SST : Regression over the global mean SST time series

removed • Atmosphere : detrend

Global SST warming

Atlantic Multidecadal Oscillation

AMO = low pass (10-yr) filtered North Atlantic SST

AMO-proj = SST filtered with a ¼ ½ ¼ filtered projected onto AMO spatial pattern

Climatic impact of AMO

Maximum covariance analysis

North Atlantic Horseshoe

Such mode is found in all ensemble members (at least for OND)

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Climate impact of NAH

Links horseshoe - AMO

AMO-projAMO-std

Non-stationarityMoving correlation between NAH and AMO using 20-yr window :

Moving correlation between NAH and NAO in NDJ using 20-yr window :

Ongoing work

• Remove remote influence of Indo-Pacific variability

• Explain the non-stationary in the AMO-NAH links

• Compare the relative influence of SST to that of snow cover and sea ice cover.

• Focus also on the summer impacts of AMO

The research leading to these results has received funding from the European Union 7th Framework Programme (FP7 2007-2013), under grant agreement n.308299NACLIM www.naclim.eu