A Model Study of the Role of High-Latitude Topography in the Climatic Response to Orbital Insolation Anomalies

Abstract

The response of a combined global zonal-averaged energy balance model and a continental ice-sheet model to insulation anomalies produced by orbital perturbations is examined. Although the role of ice sheet dynamics is included in the model, this paper focuses mostly on the response of the atmosphere?hydrosphere to the perturbations. The model, developed from that of Suarez and Held (1979), explicitly incorporates surface topography, surface energy balances, snow and sea-ice budgets and variable static stability. The ice-sheet model is based on a power-law rheology. It is found that the presence of a high-latitude plateau significantly increases the sensitivity of the climate to the insolation perturbation. The sensitivity is maximized when the elevation of the summer snowline is near the elevation of the plateau, as appears to be the case with Baffin Island today. There appears to be a rapid response of the seasonal cycle to an insolation anomaly through albedo?temperature feedback, and with the appearance of perennial snow on the plateau a much slower response coming from additional feedback processes associated with elevation of the growing ice-sheet surface. The sensitivity to high-latitude topography depends on model assumptions relating land and ocean atmospheric temperature profiles and on the assumptions of zonal symmetry and uniform cloudiness.