Numerical Simulation of the January and July Global Climate with a Two-Level Atmospheric Model

Abstract
The global distributions of selected climatic variables simulated by numerical integration of a two-level atmospheric general circulation model for January and July are presented in comparison with the corresponding observed climatological fields. The model has reproduced the observed large-scale patterns of sea-level pressure, lower tropospheric temperature and circulation with reasonable accuracy, although there are a number of systematic errors. In particular, the intensity of the semipermanent low-pressure centers in January in the Northern Hemisphere is overestimated, and the 400 mb temperature is too high in the tropics. Accompanying these errors are overestimates of the meridional temperature gradient and zonal westerlies in the mid-latitudes of the winter hemisphere. Although their global patterns resemble those observed, systematic amplitude errors are also present in the simulations of precipitation and evaporation (both of which the model overestimates by nearly a factor of 2 in Januar... Abstract The global distributions of selected climatic variables simulated by numerical integration of a two-level atmospheric general circulation model for January and July are presented in comparison with the corresponding observed climatological fields. The model has reproduced the observed large-scale patterns of sea-level pressure, lower tropospheric temperature and circulation with reasonable accuracy, although there are a number of systematic errors. In particular, the intensity of the semipermanent low-pressure centers in January in the Northern Hemisphere is overestimated, and the 400 mb temperature is too high in the tropics. Accompanying these errors are overestimates of the meridional temperature gradient and zonal westerlies in the mid-latitudes of the winter hemisphere. Although their global patterns resemble those observed, systematic amplitude errors are also present in the simulations of precipitation and evaporation (both of which the model overestimates by nearly a factor of 2 in Januar...