Xiangdong Zhang, Jeremy Krieger, Paula Moreira , and Soumik Basu

1. Chukchi/Beaufort Seas Surface Wind Climatology, Variability, and Extremes from Reanalysis Data: 1979-2009 Xiangdong Zhang, Jeremy Krieger, Paula Moreira, and SoumikBasu IARC and ARSC, University of Alaska Fairbanks Jing Zhang, and Steve Stegall NOAA-ISET Center, North Carolina A&T State University Martha Shulski High Plains Regional Climate Center, University of Nebraska-Lincoln

2. Outlines • Large scale control • ~ 20-25% of variance • provide background information to mesoscale model • Synoptic and mesoscale features beyond the large-scale control • rapid changes in wind speed and direction • Regional data analysis results

3. Dynamic control of the large-scale surface wind Aleutian low Beaufort high Siberian high Icelandic low

4. Dynamic control of the large-scale surface wind Arctic Oscillation shows a large fluctuations and an upward trend from 1970s to 90s. Thompson and Wallace (1998) Large-scale modulation: Beaufort high intensifies/weakens, and shifts with AO fluctuation. Positive AO Negative AO

5. Dynamic control of the large-scale surface wind Differences of Surface Air Temperature and Wind Stress Between Positive and Negative AO Xiangdong Zhang et al. (2003)

6. Arctic Oscillation largely impacts sea ice and ocean Differences of Sea Ice Properties Between Positive and Negative AO Concentration and Velocity Thickness Zhang et al. (2003)

7. Atmospheric circulation pattern has shifted (climate systems became more unstable) • Arctic Rapid change Pattern (ARP) ARP

8. Dynamic control of surface wind has changed

9. Swift phase change of ARP accelerated climate change and resulted in the extreme event of sea ice cover loss in summer 2007 ARP Index (All Months Included)

10. Extreme sea ice loss in summer 2007 is a result of multiyear polarity • and swift phase change of ARP, not a single-time, random event • The ARP phase change reversed wind pattern and reduced sea ice cover • The ARP phase change enhanced Pacific warm air and warm water inflow • The enlarged open water enhance albedo feedback • The previously warmed ocean retains the decreased sea ice • The enlarged open water enhance albedo feedback The ARP associated atmospheric and oceanic heat transport reduced sea ice and enlarged open water

11. Wind has tremendous local features beyond large-scale Dynamic control Single synoptic weather system can brings large impact on ocean and sea ice

12. Wind has tremendous local features beyond large-scale Dynamic control Large differences can occur in difference locations no matter how close they are

13. Wind has tremendous local features beyond large-scale Dynamic control Large differences can occur in difference locations no matter how close they are

14. Regional analysis of wind field • Data: North American Regional Reanalysis (NARR) from 1979-2009 with 32 km grid spacing, and 8 times daily. • Parameters to be analyzed: • Climatology of wind speeds; • Climatology of 95th percentile wind; • Climatology of wind directions.

15. Monthly climatology of wind speeds Obvious seasonality over the Beaufort/Chukchi seas; Minimum wind speeds occur in May; Maximum wind speeds occur in September and October (~7-8 m/s or greater).

16. Monthly climatology of 95th percentile of wind speeds Similar seasonality to the averaged wind speeds; Minimum wind speeds occur in May; Maximum wind speeds occur in September and October (~14-15 m/s or greater).

17. Monthly climatology of wind speed variances Obvious seasonality over the Beaufort/Chukchi seas; The largest variance occur in October.

18. Monthly climatology of 95th percentile wind speed variances Obvious seasonality over the Beaufort/Chukchi seas; The largest variance occur in October.

19. Monthly climatology of frequency of NE wind NE wind dominates over the Beaufort/Chukchi seas; The largest frequency occurs in winter and spring (larger than 60%).

20. Monthly climatology of frequency of SE wind SE wind mainly occurs over the northwest Beaufort Sea and Chukchi Sea; The largest frequency occurs in early summer.

21. Monthly climatology of frequency of SW wind SW wind mainly occurs over the north Beaufort Sea and Canada Basin; The largest frequency occurs in late summer.

22. Monthly climatology of frequency of NW wind NW wind mainly occurs over the north of the Canadian Archipelago, and Siberian coast of the Chukchi Sea; The largest frequency occurs in winter (over 60%).

23. Monthly climatology of frequency of NW wind NW wind mainly occurs over the north of the Canadian Archipelago, and Siberian coast of the Chukchi Sea; The largest frequency occurs in winter (over 60%).

24. Linear trends of wind speeds Wind speed generally has increased in the Beaufort and Chukchi seas throughout most of the year; The largest increase has occurred in September and October (90% significant level in the hatching area).

25. Linear trends of the 95th percentile wind speeds Similarly, wind speed generally has increased in the Beaufort and Chukchi seas throughout most of the year; The largest increase has occurred in September and October (90% significant level in the hatching area).

26. Linear trends of wind speed time series The wind speed had large fluctuations year by year in the Beaufort and Chukchi seas; The largest increase has occurred from July to October.

27. Linear trends of the 95th percentile wind speed time series Similarly, the wind speed considerably fluctuated in the Beaufort and Chukchi seas throughout the year; The largest increase has occurred from July to October.

28. Diurnal cycle of surface wind speeds Strong seasonality occurs for the diurnal cycle of wind speeds; Wind speeds have larger diurnal cycle in March and April over ocean, and from April through September over land.

29. Extreme/strong wind event induced by intense mesoscale system JAMSTEC ship, 2009

30. Summary • Atmospheric circulation plays a dynamic controlling role in surface wind variability and changes; • Surface wind has strong local and mesoscale features beyond the large-scale circulation control; • The monthly averaged and the 95th percentile of 8 hourly surface wind speeds present a large seasonality with a minimum in May and a maximum in September and October; • The monthly averaged and the 95th percentile of 8 hourly surface wind speeds has considerable increased in September and October during the last 30 years; • Wind speeds show clear diurnal cycle in March and April over ocean and from April through September over land.