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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