TWP-ICE/ACTIVE MONSOON CASE STUDY

Area-weighted mean reflectivity profiles based on radar measurements (white symbols) and simulations (colored lines):





Comments:

• C-Pol data at Darwin are supplied by the Australian Bureau of Meteorology. Reflectivities are instantaneous values > 0 dBZ reported at 10-min frequency and 2.5-km horizontal resolution over the TWP-ICE domain area of about 31,000 km².
• Model results are instantaneous reflectivities > 0 dBZ at 3-km elevation at 3-hr frequency and 2.5-km resolution over a square domain of about 31,000 km². Model dBZ are calculated from predicted mass concentrations and assumed size distribution parameters of rain and ice following 'A parameterization of cloud microphysics for long-term cloud-resolving modeling of tropical convection' by W. W. Grabowski, Atmospheric Research, 52, 17-41, 1999.
• Convective and stratiform areas in data and model results are identified at 3-km elevation according to the algorithm described in `Climatological characterization of three-dimensional storm structure from operational radar and rain gauge data' by M. Steiner, R. A. Houze, Jr., and S. E. Yuter, Journal of Applied Meteorology, 34, 1978-2007, 1995. Profiles are area-weighted means of reflectivities > 0 dBZ in columns identified as either convective or stratiform.
• No point is plotted at an elevation if the identified columns contain reflectivities > 0 dBZ less than 0.01% of the time, which is about equivalent to an average of at least one pixel per total domain area.
• View profiles of convective and stratiform fractional area.
• View binned frequency-by-altitude plots (comparing 3-h C-pol with 3-h model fields):
  • convective area
  • stratiform area
  • combined area (area > 0 dBZ)
• All measurement data have been downloaded from the DOE ARM data archive (www.arm.gov) and use in publications is subject to the policies described there. Any errors in plotting or representation shown here should be blamed on Ann Fridlind.

Preliminary summary:

• The model sensitivity test (free troposphere nudged to measurements with a 6-hour time-scale) generally produces slightly higher reflectivities in both convective and stratiform categories. Both simulations reproduce reflectivity best below the melting line and generally overestimate reflectivity increasingly with elevation above the melting line (although the reflectivity in a several-km layer above the melting layer is also underestimated in stratiform areas).