On the Potential Use of the Terminal Doppler Weather Radar Gust Front Detection Algorithm on the WSR-88D System. Part II: Detecting Non-gust Front Convergent Weather Phenomena

On the Potential Use of the Terminal Doppler Weather Radar Gust Front Detection Algorithm on the WSR-88D System. Part II: Detecting Non-gust Front Convergent Weather Phenomena
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Total Pages: 44
Release: 1991
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ISBN:

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This study examines the capability of the Gust Front Detection Algorithm (GFDA) developed for the Terminal Doppler Weather Radar (TDWR) system to detect other types of non-gust front weather phenomena which are associated with patterns of convergence in a Doppler-radar radial velocity field. The potential use of the GFDA as a nowcasting tool, a mesoscale forecasting tool, and as a tool to detect other kinds of aviation hazards besides gust fronts, needs investigation. The phenomena studied include synoptic fronts, sea-breeze fronts, gravity waves, terrain-induced convergence boundaries, old thunderstorm outflow boundaries, and the convergence bands within extratropical cyclones associated with enhanced precipitation. Comparisons of the convergent characteristics of these other phenomena to those of gust fronts are made. In addition, several case studies are presented to demonstrate the ability of the GFDA to detect the non-gust front phenomena.

On the Potential Use of the Terminal Doppler Weather Radar Gust Front Detection Algorithm on the WSR-88D System. Part 1: Impacts of Radar System Differences

On the Potential Use of the Terminal Doppler Weather Radar Gust Front Detection Algorithm on the WSR-88D System. Part 1: Impacts of Radar System Differences
Author:
Publisher:
Total Pages: 42
Release: 1991
Genre:
ISBN:

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The feasibility of using the gust front detection algorithm (GFDA) developed for the Terminal Doppler Weather Radar (TDWR) system on a Next Generation Weather Radar WSR-88D (formerly NEXRAD) system is assessed. The data resolution and tilt sequences of the WSR-88D system are different than TDWR, and the WSR-88D is designed to operate at greater ranges. To test the effect of the decreased data resolution of WSR-88D, TDWR-like data were degraded to the resolution of WSR-88D and the GFDA was tested on this degraded dataset. Also, the GFDA was tested on a gust front which occurred outside the normal 60-km range in which data are processed for TDWR. Results show that the degraded velocity precision of WSR-88D has little effect on the performance of the GFDA However, the larger sample volume sizes for the WSR-88D system did degrade the performance of the GFDA. The second lowest tilt angle for the WSR-88D tilt sequences is about 0.5 deg higher than TDWR, and this reduced the maximum range of gust front detectability. These tests show that the GFDA's performance on the WSR-88D system will be acceptable after a few modifications.

Development and Testing of the Gust Front Algorithm

Development and Testing of the Gust Front Algorithm
Author: Arthur Witt
Publisher:
Total Pages: 42
Release: 1987
Genre: Doppler radar
ISBN:

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Threshold changes, additions, and other refinements to the original version of the Gust Front Algorithm are documented. Threshold changes include a minimum velocity difference threshold, the maximum azimuthal separation between vectors, and maximum range separation. Additions include gust front tracking and forecasting in Cartesian coordinates, vertical continuity checks of gust front features to reduce the occurrence of false detections, and horizontal wind estimation both ahead and behind a detected gust front using single Doppler velocity data. Results of these additions and the effects of threshold changes on detection capability are presented for several case studies. Keywords: Wind shear; Doppler radar; Gust fronts.

A Gust Front Case Studies Handbook

A Gust Front Case Studies Handbook
Author: Diana Lynn Klingle
Publisher:
Total Pages: 96
Release: 1985
Genre:
ISBN:

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Gust fronts produce low altitude wind shear that can be hazardous to aircraft operations, especially during takeoff and landing. Radar meteorologists have long been able to identify gust front signatures in Doppler radar data, but in order to use the radars efficiently, automatic detection of such hazards is essential. Eight gust front case studies are presented. The data include photographs of the Doppler weather radar displays, thermodynamic and wind measurements from a 440 m high tower, environmental soundings and tables of gust front characteristics. The tabulated characteristics are those though to be the most important in developing rules for automatic gust front detection such as length and height, maximum and minimum values of reflectivity, velocity and spectrum width, and estimates of radial shear. For the cases studied, outflows could be detected most reliably in the velocity field, but useful information also could be gleaned from the spectrum width and reflectivity fields. The signal-to-noise ratio threshold was found to be a major factor in the ability of an observer to discern the gust front signature in the Doppler radar displays. Detection within the spectrum width field required a higher SNR than did the radial velocity field. Keywords: Doppler Weather Radar; Gust fronts; Low altitude wind shear; and Aviation weather hazards.