 |
| Titel |
High-resolution modelling of the seasonal evolution of surface water storage on the Greenland Ice Sheet |
| VerfasserIn |
N. S. Arnold, A. F. Banwell, I. C. Willis |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1994-0416
|
| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 8, no. 4 ; Nr. 8, no. 4 (2014-07-04), S.1149-1160 |
| Datensatznummer |
250116239
|
| Publikation (Nr.) |
 copernicus.org/tc-8-1149-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| Seasonal meltwater lakes on the Greenland Ice Sheet form when surface runoff
is temporarily trapped in surface topographic depressions. The development
of such lakes affects both the surface energy balance and dynamics of the
ice sheet. Although areal extents, depths and lifespan of lakes can be
inferred from satellite imagery, such observational studies have a limited
temporal resolution. Here, we adopt a modelling-based strategy to estimate
the seasonal evolution of surface water storage for the ~ 3600 km2 Paakitsoq region of W. Greenland. We use a high-resolution time-dependent surface mass balance model to calculate surface melt, a
supraglacial water routing model to calculate lake filling and a prescribed
water-volume-based threshold to predict rapid lake drainage events. This
threshold assumes that drainage will occur through a fracture if V = Fa ⋅ H, where V
is lake volume, H is the local ice thickness and Fa
is the potential fracture area. The model shows good agreement between
modelled lake locations and volumes and those observed in nine Landsat 7 ETM
images from 2001, 2002 and 2005. We use the model to investigate the lake
water volume required to trigger drainage, and the impact that varying this
threshold volume has on the proportion of meltwater that is stored in
surface lakes and enters the subglacial drainage system. Model performance
is maximised with values of Fa between 4000 and 7500 m2. For these
thresholds, lakes transiently store < 40% of available meltwater
at the beginning of the melt season, decreasing to ~ 5 to
10% by the middle of the melt season; over the course of a melt season,
40 to 50% of total meltwater production enters the subglacial drainage
system through moulins at the bottom of drained lakes. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|