The autumn-winter atmospheric response to the projected autumn Arctic sea ice free conditions

1. The autumn-winter atmospheric response to the projected autumn Arctic sea ice free conditions Lingling SUO, Yongqi GAO, Dong Guo, Jiping Liu, Huijun Wang, and Ola M. JOHANNESSEN

2. Motivation Large Uncertanties ! thewinteratmospherecirculaitonresponse to theautumnseaice retreat • Negative AO patterns • Francis et al., 2009; Liu et al., 2012; Cohen et al., 2012; Li and Wang, 2013 • Positive AO patterns • Screen et al., 2013a • Not classical AO patterns • Blüthgen et al., 2012; Screen et al., 2013a; Screen et al., 2013a Note:Liuetal, 2012 and Screen etal, 2013a obtainedthecontraryresults by theutilizationofthe same model and different ensembles. Implyingtheimportanceoftheinternalvariability!

3. Strongsnowstorms and coldness hit Europe! Possbile link between Arctic seaicereteat and thewinterclimate (snowcover, coldness ……) in northernhemisphereproposed by previous studies (Liuetal, 2012; Yang and Christensen, 2012; Francis and Vavrus, 2012; etal);

4. Blue Arctic couldappearearlierthanexpected What’stheimpactontheclimate? Not clear… More intense and easierdetectableresponse?

5. Approach: • UsingAtmosphere global climatemodel : • Control simulations (CONT) (300 one-year-lastingmembers ) usingthe 100 yearmean in pre-performed present daysimulation by BCM as boundaryconditions to forcethemodel. • Sensitivityexperiments (SENS) (300 one-year-lastingmembers ) withseaiceremoval and futureprojected SST associatedwith Arctic seaicefree as boundaryconditions during autumn in Arctic. In other regions during thewholeyear and in Arctic during theotherseasons, theboundaryconditionsarethe same as thecontrol run. The differencesbetweencontrol and sensitibityexperimentsarecaused by autumnextremeseaiceconditions and associated SST in Arctic. • Using ERA Interim for comparisonwiththemodelresults.

6. Dailiyseaice area variation in Control (CONT) and sensitivity (SENS) experiment

7. seaiceconcentrationchanges between SENS and CONT Sep-Octmean Nov Dec

8. Modelvalidation Control ERAI Winter SLP Winter precipitation Winter SAT 300 ensembles mean 1979-2000mean Figure. 2

9. Similarpatterns in Oct and Nov. Oct-Novmeanpatternsareshown. The significantresponsebasicllyocculythemid-high latitudes.

10. Similarpatterns in Oct and Nov. Oct-Novmeanpatternsareshown. The significantresponsebasicllyocculythemid-high latitudes.

11. Monthlyvariationofthezonalmeanresponse

12. Fractionalsignificant signals, No robust negative or positive AO patterns. Significantresponse in thecontinential region occupytheEurope

13. Fractionalsignificant signals, No robust negative or positive AO patterns. Significantresponse in thecontinential region occupytheEurope

14. SLP anomalies (shaded) and 500hPa wavefluxanomaliy (vector)

17. Conclusion The autumn Arctic seaicefreecancausesignificantlocalwarming, atmosphericprecipitable water increase and total precipitationincrease during theautumn. The SLP over the Arctic Ocean shows negative anomalieswhiletherearethree positive anomalycenters over thenorthwest America, theEurope and thenorthofthe East Asia. Whichlooks more like 2-3 zonalwavespatternratherthantheclassical AO pattern. The autumnatmosphericresponsecan not persist during themiddle and late winterseason. The significantwinter SLP response is much more local. The robust SLP responsebasicllyoccupytheEurope. The late winterlow SLP anomaly over the East Europecould bring the intense snowfalllocally and thewarming over themid-Asia.

18. OngoingWork • In order to comparewiththeinternalvariability • The signal to noise ratio oftheatmosphericresponse • For specificresponseinterested, thedensitydistributionof 300 members in CONT and SENS. For example, the SLP and snowfall over the East Europe.

19. Future Plan • Parallelexperimentsusingocean-atmosphereoupledmodel have done. • Whataretheatmosphericresponseswhentheocean-atmosphereinteraction is included?

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