Sensitivity of an energy balance climate model with predicted snowfall rates

Abstract

To cite this article: Kenneth P. Bowman (1985) ABSTRACT A two-level zonally-averaged seasonal energy balance model with separate land and ocean temperatures and an explicit surface energy budget is used to study the effects of the snowfall rate on the extent of snow cover and ice sheets. Sensitivity experiments are performed both with and without ice sheets and with two different snowfall parameterizations. When snowfall rates are prescribed independent of latitude, higher snowfall rates increase the area of snow cover but reduce the sensitivity of the snow line to changes of the solar constant. To eliminate arbitrary assumptions about the snowfall rate. a relationship between the atmospheric transports of water vapour and sensible heat is derived and tested against observations. The relationship obtained is used to predict the meriodional transport of water vapour in the model, from which the precipitation and snowfall are calculated. The response of the hydrologic cycle to changes of the solar constant is qualitatively similar to that found in general circulation models. The snow line is more sensitive with the predicted precipitation than with the prescribed precipitation because the predicted precipitation rate increases toward the equator. When ice sheets are included, they are larger than permanent snow cover under the same conditions because the cold surface temperatures at high elevations on the ice sheet inhibit melting. Feedback effects of the ice sheets are small, in part because they are limited to 300/0 of a latitude circle in this model.