 |
| Titel |
Influence of ablation-related processes in the build-up of simulated Northern Hemisphere ice sheets during the last glacial cycle |
| VerfasserIn |
S. Charbit, C. Dumas, M. Kageyama, D. M. Roche, C. Ritz |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1994-0416
|
| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 7, no. 2 ; Nr. 7, no. 2 (2013-04-18), S.681-698 |
| Datensatznummer |
250017959
|
| Publikation (Nr.) |
 copernicus.org/tc-7-681-2013.pdf |
|
|
|
|
|
| Zusammenfassung |
| Since the original formulation of the positive-degree-day (PDD) method,
different PDD calibrations have been proposed in the literature in response
to the increasing number of observations. Although these formulations
generally provide a satisfactory description of the present-day Greenland
geometry, they have not all been tested for paleo ice sheets. Using the
climate-ice sheet model CLIMBER-GRISLI coupled with different PDD models, we
evaluate how the parameterisation of the ablation may affect the evolution
of Northern Hemisphere ice sheets in the transient simulations of the last
glacial cycle. Results from fully coupled simulations are compared to
time-slice experiments carried out at different key periods of the last
glacial period. We find large differences in the simulated ice sheets
according to the chosen PDD model. These differences occur as soon as the
onset of glaciation, therefore affecting the subsequent evolution of the ice
system. To further investigate how the PDD method controls this evolution,
special attention is given to the role of each PDD parameter. We show that
glacial inception is critically dependent on the representation of the
impact of the temperature variability from the daily to the inter-annual
time scale, whose effect is modulated by the refreezing scheme. Finally, an
additional set of sensitivity experiments has been carried out to assess the
relative importance of melt processes with respect to initial ice sheet
configuration in the construction and the evolution of past Northern
Hemisphere ice sheets. Our analysis reveals that the impacts of the initial
ice sheet condition may range from quite negligible to explaining about half
of the LGM ice volume depending on the representation of stochastic
temperature variations which remain the main driver of the evolution of the
ice system. The main findings of this paper underline the need for
conducting studies with high resolution climate models coupled to detailed
snow models to better constrain the temporal and spatial variations of the
PDD parameters. The development of such approaches could improve the
calibration of the PDD formulation which is still widely used in climate-ice
sheet studies. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|