1. Sensitivity of atmospheric near-land temperature in Northern Europe to SST Andrey Vlasenko, Armin Köhl, Detlef Stammer University Hamburg

2. Goals To identify sensitivities of predictable elements over northern Europe, such as air temperature or precipitation, on parameters in the North Atlantic and the Arctic, such as 1. ) SST done 2. ) sea surface salinity to be done 3. ) sea ice thickness and concentration to be done

3. The Model CESAM = PLASIM(atmosphere) + MITgcm(ocean). The Driver Program CESAM Initialize Atmosphere and Ocean The Main Loop Postprocessiong Interpolator RESULT MITgcm MITgcm ocean(1 step) PLASIM PLASIM Atmosphere (10 steps) Interpolator

4. The Adjoint Model TAF AD(CESAM) = CESAM AD* * S. Blessing, T. Kaminski, F. Lunkeit, I. Matei, R. Giering, A. Köhl, M. Scholze, K. Fraedrich, and D. Stammer. Testing variational estimation of process parameters and initial conditions of an Earth System Model. TellusA, 2014 The adjoint model was obtained as a result of collaboration of Fastopt and University of Hamburg.

5. Plan of the Experiment 1.Spin up the climate model CESAM, until the proper climatology is established 2.Develop such cost functional that a) measures the atmospheric near-land temperature in Europe b)gives the gradient with minimum numerical noise during the adjoin computations 3.Using TAF AD tool, obtain the adjoint of CESAM 4.Investigate the dependence of the sensitivity with respect to NAO phase

6. The Experiment

7. Results 1. Near land temperature sensitivity to SST, negative NAO 2. Near land temperature sensitivity to SST, positive NAO 1 2

8. Results 1. Near land temperature (NLT) sensitivity to SST, negative NAO

9. . Sensitivity of NLT to SST after 24 h, NAO-

10. Sensitivity of NLT to SST after 48 h, NAO-

11. Sensitivity of NLT to SST after 62 h, NAO-

12. Sensitivity of NLT to SST after 100 h, NAO-

13. Results 2. NLT sensitivity to SST, NAO+

14. Sensitivity of NLT to SST after 24 h, NAO+

15. Sensitivity of NLT to SST after 48 h, NAO+

16. Sensitivity of NLT to SST after 62 h, NAO+

17. Sensitivity of NLT to SST after 100 h, NAO+

18. Results Contribution of sensible heat fraction in sensitivity of NLT to SST

19. Sensible heat fraction after 24 h, NAO+

20. Sensible heat fraction after 48 h, NAO+

21. Sensible heat fraction after 62 h, NAO+

22. Sensible heat fraction after 100 h, NAO+

23. Comparison with the results of A. Czasa and C Frankignoul* SST regression maps showing the tripole (in K, gray shading, dashed contours for negative) and the North Atlantic horseshoe patterns (thick contours, every 0.1 K, dashed for negative). * A. Czasa and C Frankignoul: Observed Impact of Atlantic SST Anomalies on the North Atlantic Oscillation. J. Cli. (15) 2002.

24. Conclusions 1. The sensitivity of atmosphere to SST in a framework of Coupled model can be estimated. 2.It was shown that SST affects the atmosphere in Europe mainly via changes in flux of latent heat. 3. Correlation between a. complete sensitivity patterns, obtained for negative and positive NAO equals 0.63 b. Sensitive heat fraction, obtained for negative and positive NAO equals 0.74 2.It was shown that sensitivity pattern is dependent on pressure fluctuations. 3. Optimal patterns resemble the regression patterns SST/NAO, suggesting that SST most efficiently affects the atmospheric circulation by triggering an NAO type response.

25. Thank you

26. 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