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| Titel |
The effect of more realistic forcings and boundary conditions on the geometry and volume of the Greenland ice sheet compared with EISMINT-3 |
| VerfasserIn |
E. J. Stone, D. J. Lunt, P. J. Valdes |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250021718
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| Zusammenfassung |
| Ice thickness and bedrock topography are essential boundary conditions for the numerical
modelling of the evolution of the Greenland ice sheet. The datasets currently in use by the
majority of Greenland ice sheet modelling studies are over a decade old and based on data
collected from the 1970s (Letreguilly et al., 1991). An up-to-date and more accurate dataset
of ice thickness in conjunction with a Digital Elevation Model of the Greenland bedrock
topography has subsequently been produced (Bamber et al., 2001). Significant differences
have been found between these two sets of data which have considerable impacts on the ice
sheet dynamics of numerical models and therefore the resultant ice sheet geometry and
volume.
In addition to these boundary conditions, ice sheet models are sensitive to the
temperature and precipitation used to force the surface mass balance model. We compare
results using the forcings applied in the EISMINT-3 exercise with more realistic,
present-day temperatures derived from the AVHRR APP-x satellite dataset and ERA-40
precipitation.
The GLIMMER ice sheet model was run offline using both sets of boundary conditions
and forcings until equilibrium was reached. When only the bedrock topography and ice sheet
thickness are varied the new dataset (Bamber et al., 2001) results in an increase in ice
sheet volume of 13% compared with the older (Letreguilly et al., 1991) dataset.
Furthermore, when the temperature forcing is varied the recent temperature dataset
gives an ice volume 6.5% larger than the dataset used in EISMINT-3. This work
highlights the need to assess carefully future and past Greenland ice sheet modelling
results in terms of the forcings and boundary conditions applied as well as tuning
of the model in terms of lapse rate corrections and Positive Degree Day factors. |
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