JAN LENAERTS SNOWDRIFT CLIMATE Snowdrift climate of Greenland and Antarctica Jan Lenaerts Michiel...
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JAN LENAERTS SNOWDRIFT CLIMATE Snowdrift climate of Greenland and Antarctica Jan Lenaerts Michiel van den Broeke Institute for Marine and Atmospheric Research, Utrecht University, Netherlands
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Transcript of JAN LENAERTS SNOWDRIFT CLIMATE Snowdrift climate of Greenland and Antarctica Jan Lenaerts Michiel...
JAN LENAERTS
SNOWDRIFT CLIMATE
Snowdrift climate of Greenland and Antarctica
Jan LenaertsMichiel van den Broeke
Institute for Marine and Atmospheric Research, Utrecht University, Netherlands
JAN LENAERTS
SNOWDRIFT CLIMATE
Goals
SMB = PR - RU - SUs - SUds - ERds
DECEMBER 8, 2011 2AGU FALL MEETING 2011
INTR
OD
UC
TIO
N
surface mass balance
Snowdrift sublimationSnowdrift erosion
Regional climate model (RACMO2)
+Snowdrift routine
JAN LENAERTS
SNOWDRIFT CLIMATE
DOMAIN GREENLAND ANTARCTICAHORIZONTAL RESOLUTION
11 KM 27 KM
SIMULATION PERIOD 1960-2010 1979-2010
LATERAL FORCING
ERA-40 / ERA-INTERIM
ERA-INTERIM
Methodology
3AGU FALL MEETING 2011DECEMBER 8, 2011
METH
OD
S
JAN LENAERTS
SNOWDRIFT CLIMATE
Spatial variability
DECEMBER 8, 2011 4AGU FALL MEETING 2011
GrIS AIS
SUds (Gt y-1)
24 171
% of snowfall
3 6
% of ablation
8 74
ERds (Gt y-1)
1 4
RES
ULT
S I
JAN LENAERTS
SNOWDRIFT CLIMATE
AGU FALL MEETING 2011 5
Interannual variability
DECEMBER 8, 2011
GREENLAND
RES
ULT
S I
I
JAN LENAERTS
SNOWDRIFT CLIMATE
Seasonal variability
DECEMBER 8, 2011 6AGU FALL MEETING 2011
ANTARCTICA
Summer: SUs and Melt // Winter: only SUds
Annual cycle in SUds related to wind speed and surface snow conditions
RES
ULT
S I
II
JAN LENAERTS
SNOWDRIFT CLIMATE
AGU FALL MEETING 2011 7
Wind climate
DECEMBER 8, 2011
EV
ALU
ATIO
N I
115 quality-controlled AWS stations
JAN LENAERTS
SNOWDRIFT CLIMATE
AGU FALL MEETING 2011 8
Wind climate (II)
DECEMBER 8, 2011
Entire ice sheet Without “rough” areas
• Horizontal resolution is crucial• Extreme wind speeds are underestimated
EV
ALU
ATIO
N I
I
JAN LENAERTS
SNOWDRIFT CLIMATE
Wind climate (III)
DECEMBER 8, 2011 9AGU FALL MEETING 2011
EV
ALU
ATIO
N I
II
JAN LENAERTS
SNOWDRIFT CLIMATE
AGU FALL MEETING 2011 10
Snowdrift frequency
DECEMBER 8, 2011
In-situ stations
EV
ALU
ATIO
N I
VNeumayer station, DML, East Antarctica
JAN LENAERTS
SNOWDRIFT CLIMATE
AGU FALL MEETING 2011 11
Snowdrift frequency (II)
DECEMBER 8, 2011
Palm et al., 2011
Laser altimetry + DEM -> depth of snowdrift layer
Only strong events (> 20 m) and non-cloudy conditions
EV
ALU
ATIO
N V
JAN LENAERTS
SNOWDRIFT CLIMATE
Ablation areas
DECEMBER 8, 2011 AGU FALL MEETING 2011 12
EV
ALU
ATIO
N V
I
Snowdrift (partly) explains presence and location of ablation areas
JAN LENAERTS
SNOWDRIFT CLIMATE
• First attempt of describing snowdrift climate on large ice sheets
• Model evaluation focuses on wind speed climate and snowdrift frequency (in-situ and from space)
• Snowdrift sublimation is a significant contributor to the ice sheet SMB, mainly on Antarctica and in winter
• Snowdrift erosion is locally important• Snowdrift increases near-surface
humidity and impacts top snow layer characteristics
Conclusions
DECEMBER 8, 2011 AGU FALL MEETING 2011 13
CO
NC
LU
SIO
NS
