Publications
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Supporting the deployment of the Terminal Doppler Weather Radar (TDWR)
September 1, 1994
Journal Article
Published in:
Lincoln Laboratory Journal, Vol. 7, No. 2, Fall 1994, pp. 379-398.
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The Terminal Doppler Weather Radar (TDWR) program was initiated in the mid-1 980s to develop a reliable automated Doppler-radar-based system for detecting weather hazards in the airport terminal area and for providing warnings that will help pilots avoid these hazards when landing and departing. This article describes refinements made to the TDWR system since 1988, based on subsequent Lincoln Laboratory testing in Kansas City, Missouri, and Orlando, Florida. During that time, Lincoln Laboratory developed new capabilities for the system such as the integration of warnings from TDWR and the Low Level Wind Shear Alert System (LLWAS). Extensive testing with the Lincoln Laboratory TDWR testbed system has reconfirmed the safety benefits of TDWR.
Summary
The Terminal Doppler Weather Radar (TDWR) program was initiated in the mid-1 980s to develop a reliable automated Doppler-radar-based system for detecting weather hazards in the airport terminal area and for providing warnings that will help pilots avoid these hazards when landing and departing. This article describes refinements made to...
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ITWS and the NWS forecaster: what is the connection?
June 1, 1994
Journal Article
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Nat. Weather Dig., Vol. 18, No. 4, June 1994, pp. 43-47.
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The Federal Aviation Administration (FAA) is sponsoring the development of the Integrated Terminal Weather System (ITWS), which is designed to acquire all of the weather data that is available in the terminal area, both ground-based and aircraft sensed, and to provide short-term (0 to 30-minute) predictions of microbursts, wind shear, gust fronts, runway winds and terminal-area ceiling and visibility. Additionally, the ITWS will be generating the 4-dimensional wind field at many levels in the terminal area, mainly for use by other FAA terminal air traffic control automation systems, but also available as a graphical display. An area of interest and concern to the developers is the interaction between the automated, very-short-term predictions of the ITWS, and the National Weather Service (NWS) aviation meteorologist, who is responsible for issuing terminal forecasts and other aviation advisory and warning products. This paper will describe the ITWS as currently planned and will explore the possible relationships between the ITWS and the NWS forecaster. Consideration will also be given to the NWS's new Advanced Weather Interactive Processing System (AWIPS) and how ITWS information might be used in the terminal forecasting process. This paper is intended to spark discussion of the role of the ITWS in the NWS forecasting process of the future.
Summary
The Federal Aviation Administration (FAA) is sponsoring the development of the Integrated Terminal Weather System (ITWS), which is designed to acquire all of the weather data that is available in the terminal area, both ground-based and aircraft sensed, and to provide short-term (0 to 30-minute) predictions of microbursts, wind shear...
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A microburst prediction algorithm for the FAA Integrated Terminal Weather System
April 4, 1994
Conference Paper
Published in:
SPIE, Vol. 2220, Sensing, Imaging, and Vision for Control and Guidance of Aerospace Vehicles, 4-5 April 1994, pp. 194-204.
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Lincoln Laboratory is developing a prototype of the Federal Aviation Administration (FAA) Integrated Terminal Weather System (ITWS) to provide improved aviation weather information in the terminal area by integrating data and products from various FAA and National Weather Service (NWS) sensors and weather information systems. The ITWS Microburst Prediction product is intended to provide and additional margin of safety for pilots in avoiding microburst wind shear hazards (Fig. 1). The product is envisioned for use by traffic managers, supervisors, controllers, and pilots (directly via datalink). Our objective is to accurately predict the onset of microburst wind shear several minutes in advance. The approach we have chosen in developing the ITWS Microburst Prediction algorithm emphasizes fundamental physical principles of thunderstorm evolution and downdraft development, incorporating heuristic and/or statistical methods as needed for refinement. Image processing and data fusion techniques are used to produce an "interest" image (Delanoy etal., 1991, 1992) that reveals developing downdrafts. We use Doppler radar data to identify regions of growing thunderstorms and probable regions of downdraft, and combine these with measures of the ambient temperature structure (height of the freezing level, lapse rate in the lower atmosphere; Wolfson 1990), total lightning flash rate, and storm motion to predict the microburst location, timing, and outflow strength. There is also a simple feedback system based on the results of the Microburst Detection algorithm that desensitizes prediction thresholds if false predictions are being reported. The following slides describe the preliminary ITWS Microburst Prediction algorithm design, and show examples of feature detector, and the algorithm output on one test case. Results from off-line testing on 17 days of data from Orlando are also presented.
Summary
Lincoln Laboratory is developing a prototype of the Federal Aviation Administration (FAA) Integrated Terminal Weather System (ITWS) to provide improved aviation weather information in the terminal area by integrating data and products from various FAA and National Weather Service (NWS) sensors and weather information systems. The ITWS Microburst Prediction product...
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Variable-PRI processing for meteorologic Doppler radars
March 29, 1994
Conference Paper
Published in:
1994 IEEE Natl. Radar Conf., 29-31 March 1994, pp. 85-90.
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In this communication we described how, with nonuniform sampling, the concept of bandlimited extrapolation can be used to obtain unambiguous Doppler velocity estimates in the supra-Nyquist region. The proposed method coherently processes a multi-PRI sample using a generalized form of periodogram analysis. The work is described in the context of meteorologic Doppler processing and includes a discussion of effective suppression for stationary ground clutter when multi-PRI schemes are used.
Summary
In this communication we described how, with nonuniform sampling, the concept of bandlimited extrapolation can be used to obtain unambiguous Doppler velocity estimates in the supra-Nyquist region. The proposed method coherently processes a multi-PRI sample using a generalized form of periodogram analysis. The work is described in the context of...
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The gust-front detection and wind-shift algorithms for the Terminal Doppler weather radar system
October 1, 1993
Journal Article
Published in:
J. Atmos. Ocean. Technol., Vol. 10, October 1993, pp. 693-709.
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The Federal Aviation Administration's Terminal Doppler Weather Radar (TDWR) system was primarily designed to address the operational needs of pilots in the avoidance of low-altitude wind shears upon takeoff and landing at airports. One of the primary methods of wind-shear detection for the TDWR system is the gust-front detection algorithm. The algorithm is designed to detect gust fronts that produce a wind-shear hazard and/or sustained wind shifts. It serves the hazard warning function by providing an estimate of the wind-speed gain for aircraft penetrating the gust front. The gust-front detection and wind-shift algorithms together serve a planning function by providing forecasted gust-front locations and estimates of the horizontal wind vector behind the front, respectively. This information is used by air traffic managers to determine arrival and departure runway configurations and aircraft movements to minimize the impact of wind shifts on airport capacity. This paper describes the gust-front detection and wind-shift algorithms to be fielded in the initial TDWR systems. Results of a quantitative performance evaluation using Doppler radar data collected during TDWR operational demonstrations at the Denver, Kansas City, and Orlando airports are presented. The algorithms were found to be operationally useful by the FAA airport controllers and supervisors.
Summary
The Federal Aviation Administration's Terminal Doppler Weather Radar (TDWR) system was primarily designed to address the operational needs of pilots in the avoidance of low-altitude wind shears upon takeoff and landing at airports. One of the primary methods of wind-shear detection for the TDWR system is the gust-front detection algorithm...
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The Integrated Terminal Weather System (ITWS) storm cell information and weather impacted airspace detection algorithm
August 2, 1993
Conference Paper
Published in:
Fifth Int. Conf. on Aviation Weather Systems, 2-6 August 1993, pp. 40-44.
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The Integrated Terminal Weather System (ITWS) is an FAA-sponsored program (Sankey, 1993; Ducot, 1993) whose objective is to acquire data and products from a variety of weather sensors, integrate the data and create aviation weather products for users, such as Air Traffic (AT) controllers and traffic managers, pilots, and airline and airport operations managers. The goal of ITWS is to increase capacity at airports, reduce controller workload, and enhance safety. The objective of the ITWS Storm Cell Information (StoCel) and Weather Impacted Airspace (WIA) Detection products is to identify storm cell characteristics (echo top, echo bottom, presence of heavy rain, hail, etc.) and airspace that pilots are likely to avoid because it contains hazardous weather. The StoCel/WIA products rely on the integration of pencil-beam data and products and Air Surveillance Radar (ASR-9) Weather Channel data. ASR-9 radars are useful because they cover the entire airspace of interest, perform a volume update at roughly 30-second intervals, and will be the weather representation most widely available to the Air Traffic Control (ATC) community. On the other hand, the ASR-9 has a 4.8° fan beam which results in a vertical integration over the depth of a storm, so information on the vertical structure of storms is lost. In addition, the current ASR-9 Weather Channel may produce false weather regions during ducting or anomalous propagation (AP) conditions. Nearby WSR-88D radars also cover the entire airspace of interest and provide indications of storm vertical structure. However, the volume update rate is typically on the order of 5 to 10 minutes, depending on the scanning strategy. TDWR radars perform volume updates about every 2.5 to 3 minutes, but perform sector scans that do not cover the entire airspace. Integration of the data from these various sensors produces a product that is superior to a product based on any single sensor. Field tests of components of this algorithm were conducted at Dallas-Ft. Worth (DFW) and Orlando (MCO) International Airports during the summer of 1993. The objectives of these tests are to evaluate the technical performance of the algorithm and the validate the operational concept. This paper will describe the algorithm, and discuss the operational concept and functional requirements for the product. A summary of the results and experiences of the Summer 1993 field tests, and a preliminary evaluation of the performance of the algorithm based on off-line and real-time tests will be provided at the conference.
Summary
The Integrated Terminal Weather System (ITWS) is an FAA-sponsored program (Sankey, 1993; Ducot, 1993) whose objective is to acquire data and products from a variety of weather sensors, integrate the data and create aviation weather products for users, such as Air Traffic (AT) controllers and traffic managers, pilots, and airline...
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Assessment of the benefits for improved terminal weather information
August 2, 1993
Conference Paper
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5th Int. Conf. on Aviation Weather Systems, 2-6 August 1993, pp. 414-416.
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An important part of the FAA Aviation Weather Development Program is a system, the Integrated Terminal Weather System (ITWS), that will acquire data from the various FAA and National Weather Service (NWS) sensors and combine these with products from other systems (e.g., NWS Weather Forecast Offices and the FAA Aviation Weather Products Generator). This wide variety of input data and products will enable the ITWS to provide a unified set of weather products for safety and planning/capacity improvement for use in the terminal area by pilots, controllers, terminal area traffic managers, airlines, airports, and terminal automation systems (e.g., Terminal Air Traffic Control Automation (TATCA) Center Tracon Advisory System (CTAS) [Andrews and Welch, 1989] and wake vortex advisory systems.
Summary
An important part of the FAA Aviation Weather Development Program is a system, the Integrated Terminal Weather System (ITWS), that will acquire data from the various FAA and National Weather Service (NWS) sensors and combine these with products from other systems (e.g., NWS Weather Forecast Offices and the FAA Aviation...
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Dissemination of terminal weather products to the flight deck via data link
August 2, 1993
Conference Paper
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Fifth Int. Conf. on Aviation Weather Systems, 2-6 August 1993, pp. 348-352
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Flight crews need tiimely information about terminal weather conditions when approaching or departing airports. This paper describes a new concept in providing this information from new ground-based terminal weather sensors currently being deployed via new and existing data link systems. Currently, pilots rely on ATIS (Automatic Terminal Information System) for airport weather conditions. However, the Surface Observation (SAO) contained in the ATIS message is nominally only updated once per hour. Special observations are issued more frequently, but are difficult to keep current manually in rapidly changing conditions. The Automated Surface Observing System (ASOS) and Automated Weather Observing Systems (AWOS) are beginning to supplant manual surface observations in many locations. These automated systems offer the advantage of providing continuous , automated surface observations. However, the surface observations issued by these units lack the remarks section provided by manual observers, including such information as the location and motion of storm activity in the airport area. The shortcomings of the current ATIS system were illustrated by an incident at Kansas City International Airport (MCI) in the evening of September 8, 1989. An aircraft approaching from the west received an ATIS message indicating 10 miles visibility at the airport. However, unknown to the crew, an intense storm was approaching the airport from the East. By the time the aircraft reached the airport (about 30 minutes after the initial ATIS message was received), the visibility had dropped to 1/2 nmi, but the flight crew was not notified. The aircraft subsequently struck power lines while on final approach and was forced to make an emergency landing at an alternate airport. This example provides a vivid example of current shortcomings in the generation and dissemination of terminal weather information to the flight deck. Besides improving safety, improved access to terminal weather information would provide economic benefits by allowing more efficient flight planning and utilization of air space.
Summary
Flight crews need tiimely information about terminal weather conditions when approaching or departing airports. This paper describes a new concept in providing this information from new ground-based terminal weather sensors currently being deployed via new and existing data link systems. Currently, pilots rely on ATIS (Automatic Terminal Information System) for...
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Role of the aviation weather system in providing a real-time ATC volcanic ash advisory system
August 2, 1993
Conference Paper
Published in:
5th Conf. on Aviation Weather Systems, 2-6 August 1993.
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Inadvertent engine ingestion of volcanic ash has caused expensive damage to a number of aircraft recently and could have caused accidents in at least two cases [Casadevall, 1993]. Consequently, there is great interest in a real-time air traffic control (ATC) volcanic ash advisory system which could provide timely warnings of operationally significant ash concentrations to planes in flight as well as information for flight planning. The current system (see figure 1) is characterized by non-automatic determination of ash eruption characteristics (especially altitudes) with trajectory analysis based on the National Meteorological Center (NMC) forecast winds being used to provide warnings of future locations. SIGNETS and Airport Weather Advisories are the principal means of providing information on the ash locations to pilots and controllers. After one to three days, volcanic ask from Alaska can be transported over major portions of the US aviation system (figure 2) [Heffter, et al. 1990]. The operational use of the ash trajectory predictions which do not provide information on hazard associated with the ask density has resulted in more frequent disruption of air traffic. The most recent example was an incident on 19 September 1992 where a 17 September eruption from Mt. Spurr in Alaska resulted in a significant disruption of air traffic in the Upper Midwest. A workshop in Washington, DC [Machol, 1993] discussed many of these issues associated with the Spurr disruption and the operational response to ash clouds which had been drifting for several days.
Summary
Inadvertent engine ingestion of volcanic ash has caused expensive damage to a number of aircraft recently and could have caused accidents in at least two cases [Casadevall, 1993]. Consequently, there is great interest in a real-time air traffic control (ATC) volcanic ash advisory system which could provide timely warnings of...
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MDCRS: aircraft observations collection and uses
August 2, 1993
Conference Paper
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5th Int. Conf. on Aviation Weather Systems, 2-6 August 1993, pp. 317-321.
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The Meteorological Data Collection and Reporting System (MDCRS) was designed for the Federal Aviation Administration (FAA) and the National Weather Service (NWS) to collect, decode, store and disseminate aircraft meteorological observations. The system, targeted primarily at improving upper air wind forecasts, was fielded in 1991.
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The Meteorological Data Collection and Reporting System (MDCRS) was designed for the Federal Aviation Administration (FAA) and the National Weather Service (NWS) to collect, decode, store and disseminate aircraft meteorological observations. The system, targeted primarily at improving upper air wind forecasts, was fielded in 1991.
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