Km. Hines et al., COMBINED GLOBAL CLIMATE MODEL AND MESOSCALE MODEL SIMULATIONS OF ANTARCTIC CLIMATE, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 102(D12), 1997, pp. 13747-13760
Simulations of high southern latitudes with the high-resolution, limit
ed-area Penn State/NCAR mesoscale model, version 4 (MM4), examine the
impact of a moist physics parameterization and the success of a one-wa
y nesting inside the global NCAR community climate model, version 2 (C
CM2). Discretization is by 100 km resolution in the horizontal and 15
or 16 levels in the vertical. Initial and boundary conditions for the
simulations are provided by analyses of the European Centre for Medium
-Range Weather Forecasts or CCM2 simulations. Comparisons of dry and m
oist simulations of an austral winter month, June 1988, are used to ex
amine the role of clouds in the regional meteorology A cloud-free MM4
simulation with boundary conditions provided by CCM2 run 422 indicates
that the one-way nesting of the mesoscale model can produce significa
nt differences in the model output, including an improvement in the lo
cation of one longwave trough, reduced cold bias, and a more detailed
surface wind field. The improved location of the longwave trough over
the Atlantic Ocean is hypothesized to result from blocking induced by
the reduced cold bias. The nested simulation is sensitive to the forci
ng at the horizontal boundaries. Consequently, proper location of trou
ghs and ridges at the boundaries is required for the model to well rep
resent ail the major troughs and ridges inside the domain. The additio
n of moist physics to the mesoscale simulations tends to improve the q
uality of the simulated fields over the Southern Ocean. In particular,
the intensity of the circumpolar trough is increased. Over Antarctica
, serious deficiencies are found in the simulations with moist physics
. Excessive moisture is apparently stored in the simulated clouds:lead
ing to excessive atmospheric back radiation and, consequently, excessi
ve temperatures at the surface and higher up in the troposphere.