Bromwich, David, Francis Otieno, Keith Hines, Ohio
State University, Kevin Manning, NCAR, and Elad Shilo, Israel Meteorological
Service
Recent polar versions of
the Weather Research and Forecasting (Polar WRF) model are evaluated over an
Antarctic domain at 60 km. The impact of model improvements, large scale
circulation variability, and uncertainty in the initial and lateral boundary
conditions are examined. Model skill is found to be robust even without nudging
and not very sensitive to interannual variations. Forecast skill differs more
between seasons than between recent versions. The forecasts exhibit a cold
summer and a warm winter bias in 2-m air temperatures. Dew point temperature
statistics are similar but smaller in magnitude. Biases in both forecast wind
speed and surface pressure are positive. Deficiencies in model cloud
representation enhance longwave radiative loss from the surface and lead to the
summer cold bias. The winter warm bias results from an anomalously large
sensible heat flux toward the surface generated by the positive wind speed bias
in the stable boundary layer. The most skillful forecasts are those using
ERA-Interim reanalysis for initial and lateral boundary conditions.