School of Meteorology (Defense)

Assessing the Impact of Non-Conventional Observation Types on High-Resolution 3DVAR Analyses and ARW-WRF Forecasts

Andrew Osborne

School of Meteorology

08 December 2016, 9:00 AM

National Weather Center, Room 4140
120 David L. Boren Blvd.
University of Oklahoma
Norman, OK

A National Research Council report has recommended a planned framework for a coordinated national observing system called the nationwide Network of Networks. This approach will combine observations from private, public, and academic sources to provide a higher-quality, more robust observational network. Since Numerical Weather Prediction (NWP) model forecasts are highly dependent on accurate initial conditions, these proposed changes to the observing network are likely to have large implications on the accuracy of model forecasts and analyses.

The Dallas Fort Worth Urban Demonstration Network was developed as a testbed for this new observing approach. In this work, Observing System Experiments (OSEs) are performed on 1-km three-dimensional variational (3DVAR) analyses and 400 m Advanced Research Version of the Weather Research and Forecasting (ARW-WRF) model forecasts to obtain an understanding of the impact of the additional observational datasets included in the testbed. The main focus is the comparison of impacts from radar data from the three different radar networks available in the area at this time. These include an X-band radar network developed by the Center for Collaborative Adaptive Sensing of the Atmosphere (CASA), Next Generation (WSR-88D NEXRAD) S-band radars, and Terminal Doppler Weather Radar (TDWR) C-band radars at the airports in the area. Data impacts from non-conventional surface networks (Weatherbug, Citizen Weather Observer Program (CWOP), and Understory) are also assessed. The case studied is the 26 December 2015 tornado event with specific focus on a supercell in northeast Dallas County which produced an EF4 tornado passing near Rowlett, TX. Analysis includes comparison of 0-1 km updraft helicity (UH) tracks from each experiment, verification of these modeled rotation tracks with the observed damage path/radar-estimated rotation track, and computation of fractions skill score (FSS) values for reflectivity and accumulated rainfall. The results show that the WSR-88D radar network provided the most important data for development of an accurate representation of the rotating updraft associated with this simulated storm.

School of Meteorology (Defense) Seminar Series website