1. The Arctic Climate Paquita Zuidema, RSMAS/MPO, MSC 118, Feb, 29, 2008

2. SHEBA Surface Heat Budget of the Arctic

3. Early May ~ 76N, 165 W

4. WHY ? GCMs indicate Arctic highly responsive to increasing greenhouse gases (e.g. IPCC) Clouds strongly influence the arctic surface and atmosphere, primarily through radiative interactions Factors controlling arctic cloudiness not well known Observational evidence may support predictions: (Serreze et al. 2000)

5. Characterization and Radiative Impact of a Springtime Arctic Mixed-Phase Cloudy Boundary Layer observed during SHEBA Paquita Zuidema University of Colorado/ NOAA Environmental Technology Laboratory, Boulder, CO

6. annual Increased Spring And Summer Cloudiness 1982-1999 AVHRR data (Wang&Key, 2003) Persistent springtime cloud cover may advance snowmelt onset date (e.g., modeling study of Zhang 1996) spring summer

7. Surface-based Instrumentation: May 1-8 time series dBZ 35 GHz cloud radar ice cloud properties depolarization lidar-determined liquid cloud base Microwave radiometer-derived liquid water paths 4X daily soundings. Near-surface T ~ -20 C, inversion T ~-10 C -5-45 -20 1 2345678 day z -30C 4 1 8 2 4 6 8 km 100 g/m^2 day -10C lidar cloud base

8. May 4 Cloud Particle Imager data …pristine ice particles from upper cloud...super-cooled drizzle

9. Most common ice particle habit: aggregate (below liquid cloud base) number areamass spheres aggregates, small&big

10. May 6. Intrieri et al., 2002 Depolarization ratio ice water Liquid/ice discrimination based on: depolarization ratio value backscattered intensity gradient Monthly-averaged percentages of Vertical columns containing liquid (grey bars) Nov Aug LIQUID FIRST

11. Aircraft path Lidar cloud base Temperature inversion Cloud radar reflectivity time Height (km ) 1 2 dBZ 0 -50 May 4 24:00 22:0023:00 UTC Liquid Characterization

12. How do clouds impact the surface ? J noon = 60 o Clouds decrease surface SW by 55 W m -2,increase LW by 49 W m -2 Surface albedo=0.86; most SW reflected back Clouds warm the surface, relative to clear skies with same T& T & RH, by time-mean 41 W m -2* (little impact at TOA) Can warm 1m of ice by 1.8 K/day, or melt 1 cm of 0C ice per day, barring any other mechanisms !

13. Local ice production more evident when boundary layer is deeper and LWPs are higher May 3 counter-example – variable aerosol entrainment ? Quick replenishment of liquid: longer-time-scale variability in cloud optical depth related to boundary layer depth changes

15. 29 Aug 1980

16. Change in annual mean temperature (°C): 1956-2005

17. Global temperature anomalies in 2005 relative to 1951-1980

18. [from G. Juday, UAF]

20. Record Arctic sea ice minima: 2002- 2005

21. 29 Aug 1980

22. 25 Aug 2005

23. 6 Sep 2006

25. Submarine- measured sea ice thickness

26. Satellite data tells us sea-level heights, since 1992 a rise of about 2 cm

27. Impact of 1 meter (3 feet) sea level rise on FL

28. How do clouds impact the surface ? J noon = 60 o Clouds decrease surface SW by 55 W m -2,increase LW by 49 W m -2 Surface albedo=0.86; most SW reflected back Clouds warm the surface, relative to clear skies with same T& T & RH, by time-mean 41 W m -2* (little impact at TOA) Can warm 1m of ice by 1.8 K/day, or melt 1 cm of 0C ice per day, barring any other mechanisms !

30. Cumulative volume changes of glaciers (ACIA, 2005) North America Scandinavia Russia No. Hemis.

31. Extent of summer melt on Greenland

32. Now some future model projections…

33. Permafrost (CCSM) Sept. sea-ice (CCSM) Sept. sea-ice (Observed) (Holland, Lawrence)

34. Projected changes of temperature: 2070- 2090

35. Projected changes of Arctic sea ice

36. IPCC models: Arctic sea ice coverage, 1950- 2100

37. IPCC models: Projected Arctic (60-90ºN) change of surface air temperature relative to 1980-2000

39. What are we doing about it (as scientists) ?

40. 8 years of data from the North Slope of Alaska DOE/ARM site

42. Great websites with real-time data, historical fotos: http://www.arctic.noaa.gov/ http://nsidc.org http://nsidc.org/cryosphere/glance http://nsidc.org/data/seaice-index/

43. Thank you ! Paquita Zuidema, RSMAS/MPO, MSC118

44. First some pure observations…