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Contributions to the American Meteorological Society's 26th International Conference on Radar Meteorology
April 1, 1993
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-199
Summary
Eleven papers contributed by the Lincoln Laboratory Weather Sensing Group to the American Meteorological Society's 26th International Conference on Radar Meteorology, to be held May 24-28, 1993 in Norman, Oklahoma, are compiled in this volume. The work reported was sponsored by several FAA programs, including Terminal Doppler Weather Radar (TDWR), Air Surveillance Radar-9 (ASR-9), Integrated Terminal Weather System (ITWS), and Terminal Area Surveillance System (TASS). The papers are based on analyses completed over the past year at Lincoln Laboratory and in collaboration with staff at the National Severe Storms Laboratory, the University of Oklahoma, Raytheon Corporation, and the FAA Technical Center in Atlantic City, NJ. The staff members of the Weather Sensing Group have documented their studies in four major areas: Operational Systems (TDWR Operational Test and Evaluation results); Radar Operations (future airport weather surveillance requirements, a "machine intelligent" gust front detection algorithm, microburst asymmetry study results, a shear-based microburst detection algorithm, and a hazard index for TDWR-detected microbursts); Signal Processing (coherent processing across multi-PRI waveforms, clutter filter design for multiple-PRT signals, and identification of anomalous propagation associated with thunderstorm outflows); and Analysis Methods (multiple-single Doppler wind analysis using NEXRAD data, and an adjoint method wind retrieval scheme).
Summary
Eleven papers contributed by the Lincoln Laboratory Weather Sensing Group to the American Meteorological Society's 26th International Conference on Radar Meteorology, to be held May 24-28, 1993 in Norman, Oklahoma, are compiled in this volume. The work reported was sponsored by several FAA programs, including Terminal Doppler Weather Radar (TDWR)...
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Machine intelligent gust front detection
March 1, 1993
Journal Article
Published in:
Lincoln Laboratory Journal, Vol. 6, No. 1, Spring 1993, pp. 187-212.
Summary
Techniques of low-level machine intelligence, originally developed at Lincoln Laboratory to recognize military ground vehicles obscured by camouflage and foliage, are being used to detect gust fronts in Doppler weather radar imagery. This Machine Intelligent Gust Front Algorithm (MIGFA) is part of a suite of hazardous-weather-detection functions being developed under contract with the Federal Aviation Administration. Initially developed for use with the latest generation Airport Surveillance Radar equipped with a wind shear processor (ASR-9 WSP), MIGFA was deployed for operational testing in Orlando, Florida, during the summer of 1992. MIGFA has demonstrated levels of detection performance that have not only markedly exceeded the capabilities of existing gust front algorithms, but are competitive with human interpreters.
Summary
Techniques of low-level machine intelligence, originally developed at Lincoln Laboratory to recognize military ground vehicles obscured by camouflage and foliage, are being used to detect gust fronts in Doppler weather radar imagery. This Machine Intelligent Gust Front Algorithm (MIGFA) is part of a suite of hazardous-weather-detection functions being developed under...
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Airport Surveillance Radar (ASR-9) Wind Shear Processor - 1991 Test at Orlando, Florida
June 1, 1992
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-189
Summary
An operational test of a Wind Shear Processor (WSP) add-on to the Federal Aviation Administration's airport surveillance radar (ASR-9) took place at Orlando International Airport during July and August 1991. The test allowed for both quantitative assessment of the WSP's signal processing and wind shear detection algorithms and for feedback from air traffic controllers and their supervisors on the strengths and weaknesses of the system. Thunderstorm activity during the test period was intense; low-altitude wind shear impacted the runways or approach/departure corridors on 40 of the 53 test days. As in previous evaluations of the WSP in the southeastern United States, microburst detection performance was very reliable. Over 95% of the strong microbursts that affected the Orlando airport during the test period were detected by the system. Gust front detection during the test, while operationally useful, was not as reliable as it should have been, given the quality of gust front signatures in the base reflectivity and radial velocity data from the WSP. Subsequent development of a Machine Intelligent gust front algorithm has resulted in significantly improved detection capability. Results from the operational test are being utilized in ongoing refinement of the WSP.
Summary
An operational test of a Wind Shear Processor (WSP) add-on to the Federal Aviation Administration's airport surveillance radar (ASR-9) took place at Orlando International Airport during July and August 1991. The test allowed for both quantitative assessment of the WSP's signal processing and wind shear detection algorithms and for feedback...
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A comparison of the performance of two gust front detection algorithms using a length-based scoring technique
May 8, 1992
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-185
Summary
The Terminal Doppler Weather Radar (TDWR) Gust Front Algorithm provides, as products, estimates of the current locations of gust fronts, their future locations, the wind speed and sirection behind the gust fronts, and the wind shear hazard to landing or departing aircraft. These products are used by air traffic controllers and supervisors to warn pilots of potentially hazardous wind shears during take-off and landing and to plan runway reconfigurations. Until recently, an event-based scoring system was used to evaluate the performance of the algorithm. With the event-based scoring scheme, if any part of a gust front length was detected, a valid detection was declared. Unfortunately, this scheme gave no indication of how much of the gust front length was detected; nor could the probabilities be easily related to the probability of issuing a wind shear alert for a specific approach or departure path which was being impacted by a gust front. To make the scoring metric more nearly reflect the operational use of the product, a new length-based scoring scheme was devised. This scheme computes the length of the gust front detected by the algorithm. When computed over a large number of gust fronts, this length-based scoring scheme yields the probability that any part of the gust front will be detected. As improvements to the algorithm increase the length detected, the probability of detecting any part of a gust front increases. In particular, an improved algorithm means an increased probability of correctly issuing wind shear alerts for the runways impacted by a gust front, and length-based scoring is a more accurate technique for assessing this probability of detection. This paper describes the length-based scoring scheme and compares it with event-based scoring of the algorithm's gust front detection and forecast performance. The comparison of the scoring methods shows that recent enhancements to the gust front algorithm provide a substantial, positive impact on performance.
Summary
The Terminal Doppler Weather Radar (TDWR) Gust Front Algorithm provides, as products, estimates of the current locations of gust fronts, their future locations, the wind speed and sirection behind the gust fronts, and the wind shear hazard to landing or departing aircraft. These products are used by air traffic controllers...
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Terminal Doppler Weather Radar test bed operation, Orlando, January - June 1990
November 4, 1991
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-180
Summary
This semiannual report for the Terminal Doppler Weather Radar program, sponsored by the Federal Aviation Administration (FAA), covers the period from 1 January 1990 through 30 June 1990. The principal activity of this period was the transport and reassembly of the FL-2 weather radar test site from Kansas City, MO to Orlando, FL and the change of radar frequency from S-band used in Kansas City to C-band for Orlando operations. Site operations to prepare the FL-2C radar site for summer testing began in January and continued through May, when testing began. This report describes the RF hardware, the data collection, the computer systems at site, and the networks between Orlando, FL and Lexington, MA. Also included are discussions of the microburst and gust front algorithm development, data collection, display terminals, and training for Air Traffic Control (ATC) supervisors and controllers.
Summary
This semiannual report for the Terminal Doppler Weather Radar program, sponsored by the Federal Aviation Administration (FAA), covers the period from 1 January 1990 through 30 June 1990. The principal activity of this period was the transport and reassembly of the FL-2 weather radar test site from Kansas City, MO...
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Analysis of the Terminal Doppler Weather Radar algorithm for detecting rotation associated with microbursts
October 25, 1991
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-183
Summary
Rotating winds aloft occurring with downdrafts often are associated with microbursts, which are serious aviation hazards. The Terminal Doppler Weather Radar system detects microbursts and warns pilots of windshear events, partly by its use of rotation as precursors. The role of the rotation region detection algorithm in this system is described, and the improvements to it are analyzed using measured data and simulated rotation regions. The final results show a substantial overall decrease in the number of false detections generated by the algorithm due to adjustment of thresholds and additional logic, while still retaining a good probability of microburst rotation region detection (84 percent). Ideas for future enhancement are explored through techniques such as discriminant analysis and environmental wind filtering.
Summary
Rotating winds aloft occurring with downdrafts often are associated with microbursts, which are serious aviation hazards. The Terminal Doppler Weather Radar system detects microbursts and warns pilots of windshear events, partly by its use of rotation as precursors. The role of the rotation region detection algorithm in this system is...
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Results of the Kansas City 1989 Terminal Doppler Weather Radar (TDWR) operational evaluation testing
August 17, 1990
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-171
Summary
The Lincoln Laboratory Terminal Doppler Weather Radar (TDWR) testbed was used to carry out an experimental and operational hazardous weather product evaluation program for the Federal Aviation Administration (FAA) at the Kansas City International (KCI) Airport during the summer of 1989. The objective of the program was to test and refine previously tested techniques for the automatic detection of low-altitude wind shear phenomena (specifically microbursts and gust fronts) and heavy precipitation in a midwest weather environment, as well as to assess possible new products such as storm movement predictions. A successful operational evaluation of the TDWR products took place at the KCI tower and terminal radar control room (TRACON) from 15 July to 15 August 1989 and from 15 to 30 September 1989. Several supervisor and controller display refinements that had been determined from the 1988 operational evaluation at Denver were assessed as effective. The system was successful in terms of aircraft at KCI avoiding wind shear encounters during the operational period, and it was assessed as "very good" in usefulness for continuing operation by the KCI air traffic control (ATC) personnel.
Summary
The Lincoln Laboratory Terminal Doppler Weather Radar (TDWR) testbed was used to carry out an experimental and operational hazardous weather product evaluation program for the Federal Aviation Administration (FAA) at the Kansas City International (KCI) Airport during the summer of 1989. The objective of the program was to test and...
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Contributions to the American Meterorological Society 16th Conference on Severe Local Storms
August 15, 1990
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-173
Summary
Eight papers contributed by the Lincoln Laboratory Weather Sensing Group to the American Meteorological Society's 16th Conference on Severe Local Storms, to be held October 22-26, 1990 in Kananaskis Provincial Park, Alberta, Canada, are compiled in this volume. The FAA sponsored the summer 1989 field test of the Terminal Doppler Weather Radar (TDWR) system in Kansas City, Missouri to detect wind shear aviation hazards at or near the airport. The papers are based on data collected through the summer 1989 field test and on subsequent analyses and product evaluation. The staff members of Group 43, Weather Sensing, have documented their studies of the following topics: a severe microburst; a prototype microburst prediction product; average summer microburst threat prediction at an airport; microburst asymmetry; the effect of radar viewing angle on the performance of the gust front detection algorithm; a comparison of Low-Level Wind Shear Alert System (LLWAS) anemometer-measured winds and Doppler-measured winds; and ASR-9 (Airport Surveillance Radar) adjustment of range-dependent storm reflectivity levels. The final paper is an invited paper for the Conference on microbursts. This paper discusses the precipitation-driven downdraft and the downdraft associated with the "vortex," or gust front, at the leading edge of an expanding thunderstorm outflow as two primary forms of low altitude downdraft phenomena in the microburst problem.
Summary
Eight papers contributed by the Lincoln Laboratory Weather Sensing Group to the American Meteorological Society's 16th Conference on Severe Local Storms, to be held October 22-26, 1990 in Kananaskis Provincial Park, Alberta, Canada, are compiled in this volume. The FAA sponsored the summer 1989 field test of the Terminal Doppler...
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Microburst observability and frequency during 1988 in Denver, CO
May 14, 1990
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-170
Summary
The observability of microbursts with single-Doppler radar is investigated through comparison of radar data and surface weather sensor data. The data were collected during 1988 in Denver, CO as part of the FAA Terminal Doppler Weather Radar measurement program. Radar data were collected by both and S-band and C-band radar, while surface data were taken from a mesoscale network of 42 weather sensors in the vicinity of Denver's Stapleton International Airport. Results are compared with previous similar studies of observability using data from 1987 in Denver, and 1986 in Huntsville, AL. A total of 184 microbursts impacting the surface mesonet were identified. For those microbursts for which both radar and surface data were available, 97% were observable by single-Doppler radar. This compares to 94% observability during 1987 in Denver, and 98% during 1986 in Huntsville. Two strong microbursts (at lease 20 m/s differential velocity) were unobservable by radar throughout their lifetime: one due to low signal-to-noise ratio, and the other due initially to an asymmetric outflow with low signal-to-noise ratio also a contributing factor. Two other microbursts, with differential velocities from 10-19 m/s, were unobservable by radar: one due to shallow outflow with a depth limited to a height below that of the radar beam, and one due to asymmetric outflow oriented unfavorably with respect to the radar viewing angle. Consistent with previous observations, microburst occurrence was most frequent during June and July, when 94 microbursts were identified on 20 days. An anomalously high frequency was also seen in April, although the strength of these events was relatively modest. As expected, the diurnal distribution shows the late afternoon to be the most favorable time for microburst development; more than half of all events reached their maximum strength between the hours of 2-5 p.m. local time.
Summary
The observability of microbursts with single-Doppler radar is investigated through comparison of radar data and surface weather sensor data. The data were collected during 1988 in Denver, CO as part of the FAA Terminal Doppler Weather Radar measurement program. Radar data were collected by both and S-band and C-band radar...
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A preliminary study of precursors to Huntsville microbursts
October 25, 1988
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-153
Summary
Lincoln Laboratory under the sponsorship of the FAA is currently developing automated algorithms for the detection of wind shears such as microbursts and gust fronts. Previous studies have shown that these outflows can be hazardous to an airplance during takeoffs and landings. The ultimate goal of a microburst detection algorithm is the timely warning of potentially hazardous wind shears through the detection of reliable precursors. Research in Colorado and Oklahoma documented the significance of precursors such as descending reflectivity cores, convergence, rotation, and reflectivity notching as indicators that a microburst will occur in the very near future. The overall importance of an individual feature varies between regions. This investiagtion will focus on those precursors which play a dominant role in the formation of wet microbursts in the southern United States. The data analyzed in this report was gathered by the FAA TDWR S-band Doppler radar during 1985 and 1986 in Memphis, Tennessee, and Hunstville, Alabama.
Summary
Lincoln Laboratory under the sponsorship of the FAA is currently developing automated algorithms for the detection of wind shears such as microbursts and gust fronts. Previous studies have shown that these outflows can be hazardous to an airplance during takeoffs and landings. The ultimate goal of a microburst detection algorithm...
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