Monday, 30 July 2001
Performance of the updated explicit microphysics in the 20km RUC
The RUC-2 at NCEP has been running operationally with explicit clouds and precipitation since April 1998. The bulk, mixed-phase microphysics scheme in use is Reisner et al (1998, Quart J. Roy. Meteorol. Soc.) option 4, which includes explicit prediction of cloud water, rain water, cloud ice, snow and graupel, as well as number concentration of cloud ice particles. In many respects, this scheme has performed acceptably. However, several serious problems have been uncovered and fixed over the past 2 years. The new 20-km version of the RUC, running with this new version, is producing much more satisfactory treatment of supercooled cloud and rain water, graupel and snow. Our presentation will summarize salient aspects of the scheme and show examples of improved performance.