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Graduate Exam Abstract


Evan Ruzanski

Ph.D. Final

October 29, 2010, 12:30 PM

LSC 227

Nowcasting for a high-resolution radar network


Abstract: Short-term prediction (nowcasting) of high-impact weather events can lead to significant improvement in warnings and advisories and is of great practical importance. Nowcasting using weather radar reflectivity has been shown to be particularly useful. The Collaborative Adaptive Sensing of the Atmosphere (CASA) radar network provides high-resolution (0.5 km spatial, 1 min temporal, 1 dBZ) reflectivity data amenable to producing valuable nowcasts. The high-resolution nature of CASA data requires the use of an efficient nowcasting approach, which necessitated the development of the Dynamic Adaptive Radar Tracking of Storms (DARTS) and sinc kernel-based advection nowcasting methodology. DARTS is utilized in this work in two main contexts: 1) operational research and system development and 2) applied scientific research. In the operational research and system development context, DARTS was implemented operationally in the CASA Distributed Collaborative Adaptive Sensing (DCAS) system in a robust and efficient manner necessitated by the high-resolution nature of CASA data and distributed nature of the environment in which the nowcasting system operates. Nowcasts up to 15 min to support emergency manager decision-making and 1–5 min to steer the CASA radar nodes to better observe the advecting storm patterns for forecasters and researchers are currently provided by this system. Results of operational system performance during the 2009 CASA IP experiment are presented. Additionally, currently state-of-the-art scale-based filtering methods were adapted and evaluated for potential improvement of operational nowcasting performance in the CASA DCAS environment and results are presented. DARTS was also incorporated in the Weather Support to Deicing Decision Making system to provide more accurate and efficient snow water equivalent nowcasts for aircraft deicing decision support relative to the radar-based nowcasting method currently used in the operational system. Results of an evaluation using data collected from 2007–2008 by the Weather Service Radar-1988 Doppler (WSR-88D) located near Denver, Colorado, and the National Center for Atmospheric Research Marshall Test Site near Boulder, Colorado, are presented. In the context of applied scientific research, DARTS was used as a tool to study the short-term predictability of precipitation patterns depicted by reflectivity fields observed at microalpha (0.2–2 km) to mesobeta (20–200 km) scales by the CASA radar network. Additionally, DARTS was used to investigate the predictability and performance of nowcasting rainfall fields based on specific differential phase estimates, which have been shown to provide more accurate and robust rainfall estimates compared to those made from radar reflectivity data.

Adviser: Dr. V. Chandrasekar
Co-Adviser: N/A
Non-ECE Member: Dr. Paul Mielke (Statistics)
Member 3: Dr. Anura Jayasumana
Addional Members: N/A

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