This is a real-data Four Dimensional Data Assimilation (FDDA) study using MM5 in conjunction with West Texas Mesonet surface observations and ACARS (Aircraft Communications Addressing and Reporting System) profile data collected by commercial aircraft during both en route and ascent/descent phases of their flights. The high-frequency mesonet data and ACARS wind and temperature profiles are ideal for testing the effects of FDDA on short-term mesoscale numerical weather prediction. The mesonet experiments involved 35 sites with an average horizontal spacing of about 30 km, while in the ACARS case ninety five profiles were used. Results indicated that nudging the MM5 model with the surface-based data over the relatively small area of the mesonet domain had limited impact on the model’s performance. In the ACARS runs, FDDA had long-lasting impact throughout the entire model atmosphere. FDDA appeared to improve the quantitative precipitation forecasting skill of MM5 and reduce slightly the model’s warm bias at the surface. The study suggests that ACARS has potential to significantly enhance our expertise in short-term mesoscale modeling and to support the need to rapidly and accurately adjust high-resolution meteorological model forecasts to real-time observations.

Approved for public release; distribution is unlimited.ii REPORT DOCUMENTATION PAGE Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)September 2005 AUTHOR(S)Teizi Henmi, Robert Dumais, and Richard Okrasinski 5f. WORK UNIT NUMBER PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) U.S. Army Research Laboratory Computational and Information Sciences Directorate Battlefield Environment Division (ATTN: AMSRD-ARL-CI-EM) White Sands Missile Range, NM 88002-5501 PERFORMING ORGANIZATION REPORT NUMBER ARL-TR-3647 SPONSOR/MONITOR'S ACRONYM(S) 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)U.S. Army Research Laboratory 2800 Powder Mill Road Adelphi, MD 20783-1145 SPONSOR/MONITOR'S REPORT NUMBER(S)ARL-TR-3647 DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. SUPPLEMENTARY NOTES ABSTRACTA nowcast/short-range forecast method, over the domains of approximately 100 km by 100 km with grid resolution of 1.5 to 2.0 km, has been developed for the Integrated Meteorological System (IMETS). Meteorological data available in the IMETS, including Mesoscale Model Version 5 (MM5) forecast, surface, and upper-air sounding data, are used for the computation. Three-dimensional distributions of temperature, dew-point temperature, and horizontal wind vector components can be forecasted. The method is evaluated over two different areas: Dallas (TX) and Denver (CO). It was shown that the present method was valid up to 3 h over the Dallas domain, and up to 2 h over the Denver domain. Although further studies are needed over different areas and seasons, it is tentatively concluded that the present forecasting method can be used at least for 2 h.

No abstract