Stefanie Arndt, Stephan Paul, Nicolas Stoll, Christian Haas
Vertical snow structures on Antarctic sea ice
from in-situ and remote sensing measurements
Alfred Wegener Institute Helmholtz Center for Polar and Marine Research
Temporal evolution of surface properties
ocean
Antarctic
snow
ice
iceocean
snow lead
atmosphere
melt pond
Ice and snow
transport (dri3)
Lateral mel6ng Bo9om
mel6ng/ freezing
Internal mel6ng
Ice thickness
Snow depth Snowfall
Flooding Snow-ice forma2on Internal snowmelt
Superimposed ice forma2on
snow
ice
Internal ice layers
Year-round snow cover Seasonal changes in snow properties dominated by
‣ Diurnal thawing and refreezing
‣ Internal snowmelt
winter spring summer autumn winter
Objective: The challenge of scales
Large scale
(Antarctic-wide)
Regional scale (Weddell Sea)
Floe-size scale
(< 2 km)
Investigating seasonal variability of snow properties on different spatial scales
Vertical snow profiling: Local scale
Detailed characterization of the snowpack
๏ Temperature
๏ Density
๏ Salinity
๏ Stratigraphy
๏ Liquid water content
Snow pits SnowMicroPen (SMP)
High-resolution snow penetrometer retrieving essential snow structural parameters by measuring the
bonding force between snow grains
๏ Density
๏ SSA
Variability on small scales - SMP transects
PS111_SIP_3
11 February 2018, seasonal sea ice
๏ Transect length:
23 m
๏ Measurements:
twice every 0.5 m
"
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"
)
"
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"
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"
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PS111_SIP_8 PS111_SIP_7
PS111_SIP_3
PS111_SIP_2
PS111_SIP_17
PS111_SIP_14 PS111_SIP_10
25°W 25°W
30°W 30°W
35°W 35°W
40°W 40°W
45°W 45°W
50°W 50°W
55°W
60°W 20°W
65°W
72°S74°S 74°S
76°S 76°S78°S
0 20 40 60 80 100 Nautical Miles
Snow and ice stations during PS111
Ronne Ice Shelf
Berkner Island
Filchner Ice Shelf
Coats Land
Sea-ice concentration in %
15 50 100
PS111: 19 January - 14 March 2018
© R. Winkelmann
Variability on medium scales - Weddell Sea
Expected strong regional variability between seasonal and perennial sea ice
ANT-29/6: 08 June - 12 August 2013
Perennial sea ice
Seasonal sea ice
Variability on medium scales - Weddell Sea
Expected strong regional variability between seasonal and perennial sea ice
ANT-29/6: 08 June - 12 August 2013
Perennial sea ice
Seasonal sea ice
Increased grain sizes and layering indicate strong seasonality associated with snow metamorphism and thaw- freeze cycles
Snowmelt patterns from passive microwave observations - A pan-Antarctic approach
Method: Analysis of diurnal variations in brightness temperature (passive microwave, 37 GHz, vert. pol.)
Key points
Temporary snowmelt shows a latitudinal dependence Continuous snowmelt is usually 17 days after
temporary snowmelt onset observed
Results indicate four characteristic melt types Temporary Snowmelt
Onset (TeSMO)
Arndt et al., 2016 (JGR)
winter pre-melt
snow
melt autumn/winter
ERS QSCAT ASCAT
Method:
Analysis of
seasonal cycle in radar backscatter (Ku-band at 13.4 GHz, C-band at 5.6 GHz)
Arndt & Haas, in prep.
Snowmelt patterns from active microwave
observations - A perennial sea ice approach
From scatterometer data From passive microwave observations Region Pre-melt Onset Snowmelt Onset Diurnal thawing-
refreezing Onset
Temporary Snowmelt Onset (TeSMO)
Southern Weddell
Sea 27 Nov ± 25 days 16 Dec ± 19 days 19 Dec ± 13 days 21 Dec ± 11 days Northern Weddell
Sea 24 Nov ± 16 days 06 Dec ± 16 days 09 Dec ± 9 days 13 Dec ± 11 days Bellingshausen
Sea 01 Dec ± 29 days 04 Dec ± 27 days 19 Oct ± 20 days 19 Oct ± 28 days Amundsen Sea 24 Nov ± 23 days 06 Dec ± 18 days 02 Dec ± 10 days 05 Dec ± 16 days
Ross Sea 11 Dec ± 18 days 15 Dec ± 17 days 13 Dec ± 8 days 16 Dec ± 10 days All regions 29 Nov ± 10 days 10 Dec ± 12 days 09 Dec ± 5 days 12 Dec ± 8 days
Latitudinal gradient in snowmelt onset dates
๏ north: warm-air advection
๏ south: diminished warm-air advection and stronger heat loss at the snow surface
Mean snowmelt onset dates.
Arndt & Haas, in prep.
Snowmelt patterns from active microwave
observations - A perennial sea ice approach
Vertical snow structures from space
Hypothesis:
Different sensors respond to snow melt processes in different depths within the snow cover
z z z z
T (°C) 0
-15 -15 T (°C) 0
T (°C) 0
-15 -15 T (°C) 0
Pre-melt from scatterometers
Snowmelt from Ku-band
Snowmelt from Ku- and C-band
Snowmelt from scatterometer and PMW observations
time
Vertical snow structures from space
Hypothesis:
Different sensors respond to snow melt processes in different depths within the snow cover
z z z z
T (°C) 0
-15 -15 T (°C) 0
T (°C) 0
-15 -15 T (°C) 0
Pre-melt from scatterometers
Snowmelt from Ku-band
Snowmelt from Ku- and C-band
Snowmelt from scatterometer and PMW observations
time
Using satellite remote sensing sensors with different signal frequencies might allow to describe snowmelt processes in different layers (= vertical structures)
Again: The challenge of scales
Local scale
winter pre-melt snow
melt autumn/winter
Global scale
Again: The challenge of scales
Local scale
winter pre-melt snow
melt autumn/winter
Global scale Regional/ Temporal scale
Modeled snow-ice formation from Snow Buoys
[L. Rossmann et al., DFG SPP 1158 project: SCASI]
Seasonal snow
temperature profiles
[L. Tiemann et al., SPICES, EU project]
Autonomous ice- tethered platforms to study seasonal and regional variabilities of key parameters
