Influence of wind patterns on mass balance and ice sheet evolution during the LGM in North America
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We evaluated the influence of changed wind patterns on the growth of the North American ice sheet during the last glacial, specifically during the Last Glacial Maximum (LGM). For this we simulated the evolution of ice sheets in North America using a 3D ice sheet model (ANICE). Wind was implemented in the model using a two dimensional wind field, either a static Present-Day (PD) wind field or an adjusted wind field, which is an interpolation between a PD wind field and an LGM wind field. The interpolation was based on the global temperature. For the wind fields we used seven different models from the PMIP3 experiment. We also evaluated the use of either 700 hPa or 850 hPa wind fields and compared all our results with a reconstructed geological data-based modelled ice sheet. We found that the PD-wind runs - the runs where only PD wind fields are used - produced a significantly larger LGM ice sheet volume-wise than the adjusted-wind runs, but that their shape and volume was still rather different than those of the comparison ice sheet. The ice sheets from the adjusted-wind runs also differed significantly from the comparison ice sheet, but with suggested adjustments to ANICE’s wind implementation these differences might be eliminated. There wasn’t much difference in shape between the 700 hPa and the 850 hPa runs, except that at 700 hPa the ice volume was larger on average than at 850 hPa. This larger volume came closer to that of the comparison ice sheet, therefore it looks like using 700 hPa instead of 850 hPa wind fields might work better.