Content area
Full text
J. T. JOHNSON,* PAMELA L. MACKEEN,*+ ARTHUR WITT,* E. DEWAYNE MITCHELL,*. GREGORY J. STUMPF,*+ MICHAEL D. EILTS,* AND KEVIN W. THOMAS*+
ABSTRACT
Accurate storm identification and tracking are basic and essential parts of radar and severe weather warning operations in today's operational meteorological community. Improvements over the original WSR-88D storm series algorithm have been made with the Storm Cell Identification and Tracking algorithm (SCIT). This paper discusses the SCIT algorithm, a centroid tracking algorithm with improved methods of identifying storms (both isolated and clustered or line storms). In an analysis of 6561 storm cells, the SCIT algorithm correctly identified 68% of all cells with maximum reflectivities over 40 dBZ and 96% of all cells with maximum reflectivities of 50 dBZ or greater. The WSR-88D storm series algorithm performed at 24% and 41%, respectively, for the same dataset. With better identification performance, the potential exists for better and more accurate tracking information. The SCIT algorithm tracked greater than 90% of all storm cells correctly.
The algorithm techniques and results of a detailed performance evaluation are presented. This algorithm was included in the WSR-SSD Build 9.0 of the Radar Products Generator software during late 1996 and early 1997. It is hoped that this paper will give new users of the algorithm sufficient background information to use the algorithm with confidence.
1. Introduction The network of Doppler radars called Weather Surveillance Radar-1988 Doppler (WSR-88D) have been purchased, installed, and maintained by the United States National Weather Service (NWS), the Federal Aviation Administration (FAA), and the Department of Defense. This modernized network has replaced the aging WSR-57 and WSR-74 radars and become the primary severe weather warning tool used by the government and the private sector. Some advantages of this network are nationwide coverage, Doppler capabilities, and a suite of severe weather detection algorithms. A more complete description of the WSR-88D system is given in Crum and Alberty (1993).
Severe weather detection algorithms are a key element of the WSR-88D system for numerous reasons. Such algorithms can provide severe weather potential and detection products to a forecaster during severe weather warning operations. The WSR-88D algorithms used in NWS offices across the country can detect mesocyclone and tornadic vortex signatures in the Doppler velocity data and furnish...