1. Arctic Atmosphere: Weather and Climate Variability Vladimir Alexeev, David Atkinson, Uma Bhatt, Juanxiong He, Vladimir Kattsov, Igor Polyakov, Andrew Roberts, Stephen Vavrus, John Walsh, Xiangdong Zhang Participants:

2. Atmosphere Trends of air temperature changes in cloud cover Shift of circulation pattern Extreme storms Arctic OceanArctic Sea Ice Arctic Climate System Model

3. Synthesis Activities: National and international Collaborations Polar amplification: V. Alexeev, I. Polyakov (IARC); I. Esau, S. Sorokina (U. Bergen, Nansen Center); S. Byam (UAF undergrad student). Rapid Change: X. Zhang (IARC); A. Sorteberg (U. Bergen, Bjerknes Center); J. Zhang (ARSC); R. Gerdes (AWI); J. Comiso (NASA). Sea ice feedback on atmosphere: U. Bhatt (GI); J. Walsh (IARC); J. Miller (ARSC); M. Alexander, J. Scott (NOAA), C. Deser, R. Tomas (NCAR); M. Timlin (U. Illinois). Arctic System Model: J. He, A. Roberts (ARSC, IARC); L. Hinzman, J. E. Walsh (IARC); M. Holland (NCAR); J. Cassano (U. Colorado); R. Döscher (SMHI/Rossby Center); H. Mitsudera (Hokkaido University); A. Sumi (U. Tokyo). Cloudiness: S. Vavrus (U. Wisconsin); V. Alexeev, Clara Deal (IARC); U. Bhatt (GI). Multidecadal variability: I. Polyakov, V. Alexeev, X. Zhang (IARC); U. Bhatt (GI); E. Polyakova (Stanford U.).

4. WinterSummer Trends 1979-2001 Polar amplification: 3D structures in multi-datasets V. Alexeev et al.

5. Temperature trends before ( ) and after 1990 ( ), 100mb, IGRA Polar amplification: Low stratosphere temp increases since 1990 V. Alexeev et al.

6. T, o C Averages: 1980-1990 and 2000-2007 T, o C Difference Circulation changes after 1990, winter Z, km V. Alexeev et al. Lower stratosphere warming and polar vortex shift and weakening

7. EOF1 & EOF2 of North Atlantic Ocean Temperature 0-2000m Displays Trend and MDV EQ 20 40 60 80 I. Polyakov, et al.

8. Trend: Cooling in Major Northward Heat Transport Region=> Slowdown of Atlantic Circulation! MDV: Basin-wide anomaly of single sign. Regressions of SST on PC1 and PC2 Display Very Different Patterns I. Polyakov, et al.

9. In general, GCMs simulate patterns of trends better than patterns of MDV EQ 20 40 60 80 Modeling Observations I. Polyakov, et al.

10. CLT Standard Deviation ANN Total Cloudiness (%) 21st century time series of zonally averaged changes in seasonal and annual total cloud amount (CLT) from 30 o -90 o N, along with (right) the intermodel standard deviation of annual change in CLT by latitude. Data are from a set of 20 GCMs in the CMIP3 archive. Total cloud amount increases in high-latitudes but decrease in low- latitudes and large spread occurs across models in the high-latitudes S. Vavrus et al. 7% 3% 30N 90N 2000 2100

11. Trends in Sea Ice and Clouds (autumn, summer) Years 2000-2049 During RILEs Autumn clouds increase is enhanced when sea ice loss accelerates S. Vavrus et al.

12. U. Bhatt et al.

13. Summer 2007 Rapid changes in Arctic climate and the extreme sea ice loss in 2007

14. Circulation pattern shift and Arctic Rapid change Pattern (ARP) ARP acceleration X. Zhang et al.

15. ARP and the extreme sea ice loss event in summer 2007 ARP Index (All Months Included) X. Zhang et al.

16. Pacific storm tracking and wind extremes Storm genesis with respect to the Pacific Decadal Oscillation (PDO) D. Atkinson, et al.

17. 57 26 25 6 Surge, no winds Nome, AK high magnitude wind/water level events 2002 - 2006 Nome, AK high magnitude wind/water level events 2002 - 2006 Water level surge and local winds analysis, Nome Wind direction is more important than magnitude to cause surge D. Atkinson, et al. direction frequency

18. Arctic Ocean zonal mean (60-90N) salinity and temperature (1980-1999) in different CMIP3 AOGCMs CCC_T47 Evaluation of IPCC climate models in simulating Arctic Ocean V. Kattsov, et al.

19. To synthesize understanding of past and present states and improve decadal to centennial prediction of future Arctic climate and its influence on global climate. To develop a state-of-the-art Regional Arctic system model including high-resolution atmosphere, ocean, sea ice, and land hydrology component. To develop collaboration among universities and International Arctic Research Center ASM (Arctic System model) main science objectives Arctic System Model (ASM) development J. He, et al.

20. ASM Domain (Adapted from John Cassano) Arctic System Model (ASM) development J. He, et al.

21. Arctic System Model (ASM) development A. Roberts, et al.

22. Summary Cloudiness would be increased in the northern high latitudes and Arctic. The increase in autumn cloudiness shows an enhancement when sea ice loss accelerates. Disagreement between datasets is large. Lower stratospheric temperature trend changed from negative to positive around 1990 during the cold season. Polar vortex weakened and shifted toward Siberia. Atmospheric circulation exhibits an radical spatial shift during the latest decade. The finally-formed Arctic Rapid change Pattern (ARP) plays an decisive role in the rapid Arctic climate system changes. A global version of WRF has been implemented into the NCAR’s new version of global climate model CCSM4/CPL7, and one time step integration of WRF with CLM, POP/CICE has been achieved so far. Recently decreased sea ice cover over the Arctic Ocean would have significant feedback on atmosphere, leading to an anomalous subtropical high and reduced precipitation in the northern North Pacific.

23. Challenges and Concerns Uncertainties not only in models but also in data. Science: Rapid change events in the course of gradual changes. internal air-ice-sea interactions vs. external forcing. Collaborations: Vast distance to/from Alaska. Arctic System Model: …………….