Southern Globec: Snow and Ice Studies

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Southern Globec Snow and Ice Studies
photo D. Costa
D. Martinson, R. Smith, D. Perovich, B. Elder, S.
Stammerjohn, K. Claffey Chris Fritsen, Jeramie
Memmot, Sarah Marshal, Angela Gibson, Shonna
Dovel
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Snow and Ice measurements

• Snow and ice varies spatially and evolves
  temporally
• Interested in ice cover as a
• habitant
• barrier
• Snow and ice physical properties
• Snow and ice optical properties
• Time series - buoys

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Physical properties bridge watch

• Hourly observations
• ASPECT protocol
• Ice type,thickness,fraction
• Mean thickness 46 cm
• Mean concentration 0.8

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Physical properties surveys

• Measured every meter
• snow depth
• ice thickness
• freeboard
• flooded layer
• interface temperature
• Selected sites
• snowpits
• ice cores

Robert 6 August 2001 Snow depth Mean 23 cm
Standard deviation 9 Range 7 - 69 cm Ice
thickness Mean 71 cm Standard deviation
50 Range 30 - 280 cm 67 flooded
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Physical properties surveys
6 August
9 August
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Physical properties surveys

• Summary of 400 holes
• Snow depth Mean / median 16 / 11 Standard
  deviation 11
• Ice thickness Mean / median 62 / 44
• Standard deviation 44
• Freeboard Mean/median -0.9/ 0.0
• Standard deviation 9.5

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Physical properties snowpits

• Selected snowpits
• Vertical profiles of temperature density
• grain size
• grain type
• Mean density .25 g cm-3

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Physical properties ice cores

• Profiles of
• - T,S, nb
• - structure
• - crystallography
• - d O18
• About 30 sites

Date 28 JulyEvent 21Lat. 66o 21'.6 SLong. 70o
43'.1 WThickness 33 cmGranular 58Columnar
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Optical properties

• Fernando
• 11 August (1300)
• Snow depth 28 cm
• 8 cm of new snow
• 20 cm of slush.
• Ice thickness 44 cm
• Peak 490 nm
• Ice is clean

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Optical properties

• TR-6 Robert
• 6 August 2001
• Mean transmittance
• - PAR 0.0082
• - UV-B 0.0034

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Time series buoys

• 4 buoys
• 2 simple
• barometric pressure
• position
• air temperature
• 2 complex, have in addition
• snow depth
• ice thickness
• ice temperature
• ocean temperature
• spectral irradiance

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Time series buoys

• Robert
• 6 August 2001
• Latitude 68o 04
• Longitude 70o 13
• 20oC changes common
• Major snowfall
• Little change at ice bottom

Air
Snow
Water
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Time series ice growth

• Lots of snow, 130 cm
• Little change at bottom
• What if?
• Negative freeboard
• gt flooding
• gt ice growth

Air
Snow
Ice
Ocean
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Time series light levels

• 3 irradiance sensors
• Above ice, below ice, in ocean
• Each sensor had 4 wavelengths (412, 442,
  491, and 555 nm)
• Steady increase in incident
• Peaks, valleys gt sunny, cloudy
• Decrease in transmittance gt increase in
  snowdepth

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Summary

• Ice is a mess!
• Granular ice common
• Flooding and freezeback
• Surface growth of ice
• Mean snow depth 16 cm
• Mean ice thickness 62 cm
• Light transmittance lt 1
• Peak of 2-5 at 490 nm
• Time series
• 1 m of snowfall
• 60 cm of snow-ice?
• Steady increase in incident
• Not in transmittance

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Web page, CD-ROM
Coming soon