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Dear Linda, Woody Roberts pointed out a mistake in the written summary of our meeting in Norman. Could you replace the first paragraph of the section titled "Why Level II Data" with the following? Thanks! By the way, I'll send along a figure that shows these runs so you can put it on the web page. Kelvin Kelvin Droegemeier gave a briefing which depicted the impact on storm-scale NWP of using NIDS versus wide band data. Three different experiments were made using the ARPS model at 2 km resolution over all of Kansas and Oklahoma. The model was applied to the Lahoma, Oklahoma supercell storm, which began as a multicell in central Kansas, became a supercell as it moved southward into Oklahoma, and eventually became a bow echo in north Texas. Overall it had a lifetime exceeding 8 hours. In all experiments, the ARPS was initialized using the RUC analysis to provide the background fields, to which were assimilated Oklahoma Mesonet, wind profiler, and SAO surface observations. A run using this configuration was compared to an experiment in which NIDS reflectivity data were alsoadded (including various assumptions about the motion and other water substance fields), and to an experiment in which the same storm was
initialized using full WSR-88D level II data and the Shapiro single-Doppler velocity retrieval scheme (which provides high-resolution cross-beam and vertical winds, along with temperature and pressure fields). All forecasts were run for 2 hours and 20 minutes: Expt #1: RUC analysis + Mesonet + profiler + SAO Expt #2: RUC analysis + Mesonet + profiler + SAO + NIDS Expt #3: RUC analysis + Mesonet + profiler + SAO + Level II (+ retrieval)Without any radar data at all, the model never generated a storm. With NIDS data added, the storm died out within 30 minutes. With full level II data used instead of NIDS, the isolated intense storm maintained its structure, as observed, and moved in the correct direction. These runs clearly show that, without full wide band data, storm-scale NWP will, in many cases, simply not be possible (of course, when forcing is strong, e.g., in terrain, along fronts and drylines), the importance of wide band data becomes more problematic.
-------------------------------------------------------------------------- Prof. Kelvin K. Droegemeier, Director E-mail: kkd@xxxxxx Center for Analysis and Prediction of Phone: 405-325-0453 Storms FAX: 405-325-7614 University of Oklahoma WWW: http://www.caps.ou.edu Sarkeys Energy Center, Rm 1110 http://hubcaps.ou.edu 100 East Boyd Street Norman, OK 73019 USA