The performance of an explicit cloud physics parameterization is examined
with simulations of high southern latitude winter climate using a version of
the Pennsylvania State University/National Center for Atmospheric Research
Mesoscale Model, version 4. The results reveal that there are three moist
physics regimes in the vertical over the elevated interior of Antarctica:
the very cold upper troposphere, the relatively warm middle troposphere and
the cold boundary layer. Deficiencies for these layers include excessive
cloud ice in the upper troposphere, excessive cloud ice in the inversion
layer near the ice surface, overly warm temperatures in the lower
troposphere, overly cold temperatures in the upper troposphere and excessive
downward longwave radiation at the Earth’s surface. Three sensitivity
experiments were performed to investigate possible improvements in the cloud
parameterization. The results indicate that a reduction of the numerous
cloud condensation nuclei, while reducing some errors, appears to be
insufficient to improve the simulation. A reduction in the excessive cloud
ice in the upper troposphere significantly improves the simulation of
upper-tropospheric temperature.