Northern Hemisphere ice sheets and planetary waves: a strong feedback mechanism

Abstract

We carried out a statistical analysis orihe relation between the net mass balance of high-latitude glaciers and 500 mb height deviations of the seasonal mean atmosphere. Mass-balance series of 23 glaciers and ice caps were used, ranging in length from 8 to`30 yr. Considering the sample as a whole, it appeared that the only significant predictor for mass balance variations is- the summer anomaly of the 500 mb height. Except for a few individual glaciers, correlations with mean vorticity and meridional wind component turned out to be insignificant. To investigate,the potential feedback between ice-age ice sheets and planetary waves, we used a stationary two-layer atmospheric model to calculate the response to the CLIMAP (1976) ice-sheet topography for 18,000YBP. Combining the result with the statistical analysis reveals that the feedback is important: the planetary wave pattern forced by the ice sheets leads to deviations of the equilibrium-line altitude of about 500 in.