Climatic response to ice-age conditions. - Part 1: The atmospheric circulation

In part 1 (of a series of two papers) we present a simulation of the atmospheric state under ice-age conditions (18000 years before present) using the T21 Atmospheric General Circulation Model (AGCM), originally developed at the European Centre for Medium-Range Weather Forecasts. Results will be presented for the near—surface climatology (2m—temperature,10m—wind, and precipitation) for January and July. The model’s response to ice-age boundary conditions was quite consistent with paleogeological data and with AGCM—experiments of other authors. Although, the change in the mean climatic state of the atmosphere from modem to glacial conditions was statistically significant, the basic structure of the atmospheric circulation was not altered substantially. We conclude that the simulated atmospheric surface climatology can define the upper boundary conditions for a global ocean model reasonably well (part 2 of this series)