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| Titel |
Estimating the glacial melt water contribution to the fresh water budget from salinity and δ¹⁸O measurements in Godthåbsfjord |
| VerfasserIn |
Antje Fitzner, Dirk van As, Jørgen Bendtsen, Dorthe Dahl-Jensen, Xavier Fettweis, John Mortensen, Søren Rysgaard |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250071975
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| Zusammenfassung |
| The mass loss of the Greenland ice sheet increases due to changes in the surface mass balance
and accelerated ice discharge through numerous outlet glaciers at the margins. The melt has
global and local consequences. Globally the sea level rises and locally the increased fresh
water inflow affects fishery and transportation.
In this study we focus on the fjord system near Nuuk in West Greenland, Godthåbsfjord.
Godthåbsfjord is a unique fjord with its length of about 300Â km and a shallow sill at the
fjord entrance that protects the fjord system. There are several tidewater glaciers terminating
into the fjord and two land-terminating glaciers along the fjord contributing to the fresh water
content in the fjord. The largest tidewater glacier is Kangiata Nunåta Sermia. The freshwater
originates primarily from three processes: surface melt, ice berg calving and basal
melt.
Observations and climate models can give estimates for calving and surface melt. Basal melt,
however, cannot be observed directly. Even though mass loss by basal melting is neglected on
the global scale, it plays an important role in the small regional environment like fjords and
the glaciers itself. Warmer ocean temperatures increase basal melt, and resulting
lubrication accelerates tidewater glaciers. Overall, the freshwater content in the fjord
increases.
Salinity measurements taken in the fjord between 2007 and 2011 show a seasonal
variability originating from the variation in fresh water inflow. Based on salinity records only,
it is not possible to distinguish between the different fresh water sources like precipitation
and melt. Hence, δ18O measurements are used in addition to salinity records to
determine the origin of the fresh water because of the different δ18O signatures of
run-off and glacial melt water. The resulting fresh water inflow and the glacial melt
contribution are compared to independent estimates and regional climate model
output. |
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