Download or read book A Thunderstorm Gust Front Detection System Part I System Operation and Significant Case Studies Part II Statistical Results written by and published by . This book was released on 1979 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Dulles International Airport wind and wind shear detection system recorded more than 160 events from November 1976 through March 1978. Eighty-two percent of 113 significant events occurred in conjunction with thunderstorms, squall-lines and frontal passages. The chief source of false alarms for anemometers was boundary layer disturbances representing 10% of the total; while gravity shear waves related to the 500mb winds caused the most false alarms for pressure sensors (4% of the total). Using complementary arrays of wind and pressure sensors, total system false alarms can be greatly reduced. These data demonstrate the importance of stable surface layers in determining how well surface temperature and wind measurements represent flow at higher levels and explain underestimates of system severity. Moreover, because we demonstrate the value of wind vector information and since temperature is a scaler quantity, there seems little operational value in using temperature sensors as part of a detection system. Conversely, pressure sensors will not reliably detect relatively thin outflows (100-200 M thick) occurring at a distance from downflows having small dimensions. Again, the wind and pressure sensors combine to provide a total system offering good reliability for detection of thunderstorm outflows. The results suggest an array configuration (composed of wind and pressure jump sensors) for use in airport warning systems. This configuration extending about 10km from the airport provides a warning for Thunderstorm gust-fronts.

Download or read book A Thunderstorm Gust front Detection System written by A. J. Bedard and published by . This book was released on 1979 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Detection of Gust Fronts Using Surface Sensors written by A. J. Bedard and published by . This book was released on 1977 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A thunderstorm gust front detection system written by and published by . This book was released on 1979 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book THUNDER GUST FRONT DETECTION SYSTEM PART I SYSTEM OPERATION written by A. J. Bedard and published by . This book was released on 1979 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the Potential Use of the Terminal Doppler Weather Radar Gust Front Detection Algorithm on the WSR 88D System written by Gregory J. Stumpf and published by . This book was released on 1991 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Thunderstorm Gust Fronts written by United States. Federal Aviation Administration. Systems Research and Development Service and published by . This book was released on 1978 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 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 written by and published by . This book was released on 1991 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Airborne Wind Shear Detection and Warning Systems Fourth Combined Manufacturers and Technologists Conference Part 1 written by and published by . This book was released on 1992 with total page 730 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Traffic Sign Inventory Kent County Road Commission Final Report written by and published by . This book was released on 1987 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigations of Thunderstorm Gust Fronts from Project NIMROD Data written by Roger M. Wakimoto and published by . This book was released on 1981 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation investigates the thunderstorm gust front with the aid of Project NIMROD data. The main goal is to present the time dependent solution of the gust front. RHI and VAD cross sections of reflectivity and Doppler velocity were constructed for different three minute radar scans to determine the vertical structure. These analyses revealed that the life cycle of the gust front could be divided into four stages: 1) the formative stage; 2) the early mature stage; 3) the late mature stage; and 4) the dissipation stage. A new finding was a horizontal roll detected in the reflectivity patterns during stages II and III. This phenomenon was called a "precipitation roll." Rawinsonde launchings revealed the thermodynamic structure of the gust front. The cold air layer was found to correspond closely to the observed surface pressure rise. Calculations confirmed that the collision of two fluids produced nonhydrostatic pressure forces at the leading edge of the outflow. A dry, cool layer at the top of the gust front was a result of the low level outflow that was lifted vertically at the frontal boundary and advected back by the circulation within the bead of the gust front. The equation for the propagation speed of a density current was confirmed to accurately predict the movement of the gust front, thus disproving the theory that the gust front is an advecting phenomenon. Comparisons are made between the gust front and the "downburst" to emphasize their different nature.

Download or read book A Thunderstorm Gust Fron Detection System written by and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Automatic Detection of Gust Fronts written by Hiroshi Uyeda and published by . This book was released on 1985 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Application of Artificial Intelligence to Gust Front Detection with S band Polarimetric WSR 88D written by Yunsung Hwang and published by . This book was released on 2013 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development and Testing of the Gust Front Algorithm written by Arthur Witt and published by . This book was released on 1987 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book A Gust Front Case Studies Handbook written by Diana Lynn Klingle and published by . This book was released on 1985 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book 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 written by and published by . This book was released on 1991 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.