Deep water outflow from the Weddell Sea into the Scotia Sea ( SW Atlantic)
Winter sea-ice thicknesses in the Weddell Sea and their ... · Winter sea-ice thicknesses in the...
Transcript of Winter sea-ice thicknesses in the Weddell Sea and their ... · Winter sea-ice thicknesses in the...
Winter sea-ice thicknesses in the Weddell Sea
and their variability over the past 24 years
Sandra Schwegmann1, Priska Hunkeler1, Stefan
Hendricks1, Peter Lemke1, Christian Haas2, Thomas
Krumpen1, Robert Ricker1
1Alfred Wegener Institute for polar and marine research
2York University
ANT-XXIX/6: the recent winter experiment
ANT-XXIX/6
08.06.-12.08.13
Cape Town – Punta Arenas
Winter experiment
9 drilling stations
- Sea ice thickness
- Freeboard
- Snow depth
Objectives
Regional Sea Ice Thickness Distribution
Thermodynamic & Dynamic Ice Growth
Remote Sensing Validation Data
CryoSat-2 SMOS
Method Development
Improved Resolution (1D ���� 2D)
Objectives
Regional Sea Ice Thickness Distribution
Thermodynamic & Dynamic Ice Growth
CryoSat-2 SMOSComparison to other winter data
Distribution 1992 vs. 2013
Sea ice thickness Snow depth
70
60
50
40
30
20
10
0
Fre
quency 2
013
240220200180160140120100806040200
Sea ice thickness (cm)
110
100
90
80
70
60
50
40
30
20
10
0
Fre
quency 1
992
2013
1992
60
50
40
30
20
10
0
Fre
quency 2
013
1009080706050403020100
Snow depth (cm)
160
140
120
100
80
60
40
20
0
Fre
quency 1
992
2013
1992
• Sea-ice thickness distribution comparable
• Snow depth much higher in 2013
Retro Drilling-GEM comparison
0
20
40
60
80
100
120
140
160
180
200
21. Jun. 26. Jun. 1. Jul. 6. Jul. 11. Jul.
RD TIT
GEM TIT
RD sdev
GEM sdev
RD mode
Gem Mode
Winter - early spring expeditions
ANT-VIII/2
06.09. – 31.10.1989
Weddell Sea, Spring
ANT-X/4
21.05. – 06.08.1992
Weddell Sea, Winter
ANT-XXIII/7
24.08. – 29.10.2006
Western Weddell Sea, Winter-Spring
ANT-XXIX/6
08.06. – 12.08.2013
Weddell Sea, Winter
ANT-XXIX/7
14.08. – 16.10.2013
Western Weddell Sea, Winter-SpringANT-VIII/2Augstein et al., Ber. Polarforsch. 84(1991)
Sea-ice thickness comparison
800
700
600
500
400
300
200
100
0
3.53.02.52.01.51.00.50.0
24
22
20
18
16
14
12
10
8
6
4
2
0
1989
2006
2013 (ANT-29/7)
70
60
50
40
30
20
10
0
Fre
quency 2
013
240220200180160140120100806040200
Sea ice thickness (cm)
110
100
90
80
70
60
50
40
30
20
10
0
Fre
quency 1
992
2013
1992
• Sea-ice thickness distribution comparable between 1989 and 2013
• 2006 shows higher sea-ice thickness
Snow depth comparison
1.41.21.00.80.60.40.20.0
900
800
700
600
500
400
300
200
100
0
50
45
40
35
30
25
20
15
10
5
0
1989
2006
2013 (ANT-29/7)
60
50
40
30
20
10
0
Fre
quency 2
01
3
1009080706050403020100
Snow depth (cm)
160
140
120
100
80
60
40
20
0
Fre
quency 1
992
2013
1992
• Snow depth much higher than in every other year
Freeboard comparison
50
40
30
20
10
0
Fre
quency 2
01
3
-30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30
Freeboard (cm)
60
55
50
45
40
35
30
25
20
15
10
5
0
Fre
quency 1
992
2013 (ANT-29/6)
1992
500
450
400
350
300
250
200
150
100
50
0
Fre
quency 1
989
-0.30 -0.20 -0.10 0.00 0.10 0.20 0.30
Freeboard (m)
14
12
10
8
6
4
2
0
Fre
quency 2
006/2
013
1989
2006
2013 (ANT-29/7)
• Freeboard shifted to lower or more negative values in 2013
• Interesting feature: 2006 shows very low, strongly negative
shifted freeboard despite of less snow and thicker ice compared
to other years!
Sea ice extent variability
Image source: http://nsidc.org/data/seaice_index/
Summary
• Sea ice thicknesses comparable to former winter/spring
experiments
• Snow depth particularly high in 2013
• Freeboard generally more negative with higher snow
coverage
• Exception: 2006
• Comparison with model data
• Analysis: Does the snow save the sea ice
Outlook