Thursday, 15 January 2004
On The Use of Radar Observations of Reflectivity in Veryfying Model Hydrometeor Fields
Explicit cloud microphysical processes have been included in most mesoscale NWP models today. Verification of three-dimensional distribution of hydrometeors (cloud liquid water, cloud ice, rain, and snow) from model forecasts, however, remains a big challenge to most modelers due to the lack of direct measurements of these fields. Fortunately, some “indirect” measurements of these variables exist from radar observations. An alternative way to verify the model hydrometeor structures is to calculate three-dimensional radar reflectivity from model hydrometeor forecasts and then compare the calculated radar reflectivity with radar observations.
At the Naval Research Laboratory, a system has been developed to integrate radar reflectivity data from individual radars in a model domain and then interpolate the three-dimensional composite radar reflectivity to model grids for model verification. Radar raw data have been collected via the CRAFT project for several storm cases and verifications have been conducted. The results from these case studies have shown the usefulness of radar observations in verifying model hydrometeor structures and hence improving model microphysical parameterizations.