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

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

Physical properties: bridge watch Hourly observations ASPECT protocol Ice type,thickness,fraction Mean thickness = 46 cm Mean concentration ~ 0.8

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

Physical properties: surveys 6 August 9 August

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

Physical properties: snowpits Selected snowpits Vertical profiles of temperature density grain size grain type Mean density = .25 g cm-3

Physical properties: ice cores Profiles of - T,S, nb - structure - crystallography - d O18 About 30 sites Date: 28 July Event 21 Lat. 66o 21'.6 S Long. 70o 43'.1 W Thickness: 33 cm Granular: 58% Columnar: 42%

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”

Optical properties TR-6 Robert 6 August 2001 Mean transmittance - PAR: 0.0082 - UV-B: 0.0034

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 Enlarged Area August 2001 November 2001

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

Time series: ice growth Lots of snow, 130 cm Little change at bottom What if? Negative freeboard => flooding => ice growth Air Snow Ice Ocean

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 => sunny, cloudy Decrease in transmittance => increase in snowdepth

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 < 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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