A a Quantification of the Effects of Data Denial and Limitation in Mm5 Initialization on Forecast Accuracy Thesis

Using the 3-Dimensional Variational Analysis data assimilation scheme and the Pennsylvania State University (PSU)/National Center for Atmospheric Research (NCAR) Mesoscale Model 5 (MM5) as configured and run operationally by the Air Force Weather Agency (AFWA) in the European theater, input observations were denied in three different categories: total, upper air, and surface observation denial. Two control groups were run using all available data as received by AFWA. The main control group used a 6-hour old first guess as a baseline. The data denied test cases and the secondary control group used a 30-hour old first guess because it was not possible to deny data from the first guess. The secondary control group was used to estimate errors resulting from the use of different first guess forecasts between the main control group and the test cases for all forecast times. The analyses show statistically significant differences between the main control group and test cases in almost every instance. However, the surface comparisons provide little evidence of significant meteorological differences due to the relatively small magnitude of the differences in root mean square error and bias. In the upper air analyses, the largest differences emerged at the model initialization time. The magnitude of the differences rapidly diminishes as the solution of the test cases converge toward that of the main control group throughout the forecast period. Errors associated with the use of different initial and boundary conditions account for most of the resulting differences. Subject Terms Mesoscale Model, MM5, 3DVAR, 3-Dimensional Variational Analysis, Air Force Weather Agency, AFWA MM5, Numerical Weather Prediction, Model Coparison, Atmospheric Temperature, Weather Report Classification unclassified Classification of this page unclassified Classification of Abstract unclassified Limitation of Abstract UU Number of Pages 120 The views expressed in this thesis are those of the author and do not reflect the official policy or position of the United States Air Force, Department of Defense or the U.S. Government.