The Arctic Sea Ice Cover

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Jean Gray
6 years ago
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1 The Arctic Sea Ice Cover From the Living Earth Interface, Impediment, Integrator Frozen ocean 8-15 million km 2 Size of U.S. Meters thick Floating, moving ice Highly variable Large albedo

2 Climate change! Why important Exploration Economic Military Climate change Canary in a coal mine Amplifier of change

What are the major sea ice questions? How much ice is there? areal extent thickness How much snow is there? How does the ice move? What is its mass balance? Where does the sunlight go?

3 What are the major sea ice questions? How much ice is there? areal extent thickness How much snow is there? How does the ice move? What is its mass balance? Where does the sunlight go? What are its properties? How does it interact with other components? Is Arctic change related to the Arctic Oscillation? Is Arctic change a component of climate change? Are feedbacks critical to Arctic change? Do physical changes greatly impact Arctic ecosystems and society? Which Arctic changes reflect basin-wide, decadal, and long-term processes? How are they coupled? Have Arctic feedbacks amplified these changes? What are the future Arctic change scenarios? Determine the extent of the ice cover Determine the redistribution of the ice cover due to dynamics and thermodynamcs Measure the export of ice from the Arctic basin Determine the snow depth and the ice thickness Assess large-scale Arctic environmental change. Conduct scientific exploration of polar frontiers. Observe polar regions in depth. Understand human-environmental dynamics. Create new connections between science and public. How are these quantities changing?

4 What do we need to measure? Spatial and temporal variability make it difficult Ice extent Thickness distribution Snow depth distribution Ice motion Temperature Mass balance Albedo and transmission Environmental forcing (ocean and atmosphere)

5 What tools do we have? Ice tethered buoys! Archived data Field experiments camps cruises submarines Remote sensing IPS aircraft satellites Models process discrete element large-scale ice GCM

6 What is the ice extent? Satellites March Ice extent is decreasing September

7 How thick is the ice? Submarines Moorings Surface obs Satellites? Changes in summer thickness Comparing and the 1990 s Rothrock et al. show thinning everywhere! Average decrease was 40% from 3 m to under 2 m Tucker et al. show similar results for spring Sea ice is thinning everywhere

How much snow is there? Surface obs Buoys Satellites? 0.05 Average depth (cm) 40 30 20 10 Frequency (%) 0.04 0.03 0.02 0.01 Spring 1998 21,169 points 33.

8 How much snow is there? Surface obs Buoys Satellites? 0.05 Average depth (cm) Frequency (%) Spring ,169 points 33.7 cm mean 19.3 std. dev Snow depth (cm) 0 10/10 11/24 1/8 2/22 4/8 5/23 7/ D t Seasonal evolution and large spatial variability

9 How does the ice move? Variations due to changes in forcing Buoys Satellites

10 What is the mass and heat budget? Surface obs Buoys Manned camp Autonomous buoy Total melt (cm) Change in ice thickness (cm) First year 0.7 to 1.5 m 1.5 to 2.25m above 2.25 m 0 Snow melt Surface melt Bottom melt /10 12/10 2/10 4/10 6/10 8/10 10/10 Date Large variability: spatial and interannual

11 Where does the sunshine go? Surface obs Buoys Seasonal variability, melt ponds are the key.

12 Ice properties impact all parameters What are the ice properties? Surface obs Buoys Satellites

13 How does it interact? Much work to do. Surface obs

Ice tethered systems: ice measurements Ice tethered systems can make major contributions 1. Air temperature 2. Ice temperature 3. Upper ocean temperature 4. Snow depth 5. Ice thickness 6.

14 Ice tethered systems: ice measurements Ice tethered systems can make major contributions 1. Air temperature 2. Ice temperature 3. Upper ocean temperature 4. Snow depth 5. Ice thickness 6. Ice mass balance 7. Surface conditions 8. Solar partitioning 9. Ice position 1. Thermistors 2. Thermistors 3. Thermistors 4. Acoustic sensor 5. Acoustic sensor 6. Acoustic / thermistors 7. Web cams above,below 8. Spectroradiometers 9. GPS

15 Sample ice buoy results Almost as good as being there

16 Spatial variability Snow depth, ice thickness, ice conditions

What good is a point measurement? 0.4 0.3 Surface melt Fraction 0.2 0.1 0.0 0.4 0.3 Bottom melt Fraction 0.

17 What good is a point measurement? Surface melt Fraction Bottom melt Fraction Total melt (cm) Pretty good if you carefully select location

18 Smart motes Snow-ice interface temperature tells all

19 Installation measurement festival Characterize area during buoy installation Explore spatial variability Aerial photographs Snow depth Pond depth Ice thickness Surface types

20 Remember outreach Classroom visits, media outreach, web cams and pages

21 Integration coordination, and synthesis Integration is the key Models 3 levels of coordination and integration Integrate all buoy elements (ice, ocean, atmosphere, biology, geochemistry). Integrate tethered buoys with other components of an Arctic Ocean observing system (satellites, moorings, stations) Coordinate with other studies (process studies, field studies, models) Collaborate with other efforts Synthesize results Ice tethered buoys Field studies Satellites

Summary How much ice is there? areal extent thickness Yes! How much snow is there? Yes! How does the ice move? Yes! What is its mass balance? Yes! Where does the sunlight go?

22 Summary How much ice is there? areal extent thickness Yes! How much snow is there? Yes! How does the ice move? Yes! What is its mass balance? Yes! Where does the sunlight go? Yes! What are its properties? Yes! How does it interact with other components? Yes! Can ice tethered buoys help answer the questions YES!

SEARCH ice mass balance activities Sponsored by NOAA and NSF Ice mass balance buoys Deployments defined by Maximum coverage Models and observations Eight

23 SEARCH ice mass balance activities Sponsored by NOAA and NSF Ice mass balance buoys Deployments defined by Maximum coverage Models and observations Eight buoys this year Expected life 1-3 year Coordinated with moorings Ocean instruments Ice profiling sonar Collaboration with other efforts Location, location, location

Mass balance observations Beaufort Sea o Air temperature ( C) North Pole 0-10 -20-30

8-1.9 Apr 20 2000 Autonomous field experiment in a box 5 Jun 20 Aug 20 Oct 20 2002 Dec

24 Mass balance observations Beaufort Sea o Air temperature ( C) North Pole Snow -50 Ice Depth (cm) o Apr Autonomous field experiment in a box 5 Jun 20 Aug 20 Oct Dec 20 0 Feb Ocean heat flux (W m ) Water temperature ( C) Water

Spectral Albedos. a: dry snow. b: wet new snow. c: melting old snow. a: cold MY ice. b: melting MY ice. d: frozen pond. c: melting FY white ice

Spectral Albedos. a: dry snow. b: wet new snow. c: melting old snow. a: cold MY ice. b: melting MY ice. d: frozen pond. c: melting FY white ice Spectral Albedos a: dry snow b: wet new snow a: cold MY ice c: melting old snow b: melting MY ice d: frozen pond c: melting FY white ice d: melting FY blue ice e: early MY pond e: ageing ponds Extinction