Publications

The Integrated Terminal Weather System (ITWS) development program was initiated by the Federal Aviation Administration (FAA) to produce a fully automated, integrated terminal weather information system to improve the safety, efficiency and capacity of terminal area aviation operations. The ITWS will acquire data from FAA and National Weather Service (NWS) sensors as well as from aircraft in flight in the terminal area. The ITWS will provide air traffic personnel with products that are immediately usable without further metorological interpretation. These products include current terminal area weather and short-term (0-30 minute) predictions of significant weather phenomena. The Terminal area-Local Analysis and Prediction System (T-LAPS) is being evaluated as a possible provider of the Terminal Winds Product for the ITWS. T-LAPS is a direct descendant of the Local Analysis and Prediction System (LAPS) developed at the National Oceanic and Atmospheric Administraiton's (NOAA's) Forecast Systems Laboratory (FSL). T-LAPS takes meteorological data from a wide variety of data sources as input and provides a gridded, three-dimensional (3-D) analysis of the state of the local atmosphere in the terminal area as output. For the 1992 system, the output was a gridded 3-D analysis of the horizontal winds. This information is intended to be used by the Terminal Air Traffic Control Automation (TATCA) program to estimate the effects of winds on aircraft in the terminal area. The 1993 and 1994 T-LAPS systems will incorporate more sophisticated wind analysis algorithms. The T-LAPS '92 demonstration at the Lincoln Laboratory Terminal Doppler Weather Radar (TDWR) FL-2CC field site in Kissimmee, Florida, during August and September was quite successful. The primary area of coverage was a 120 km by 120 km box centered on the Orlando International Airport. The T-LAPS system was able to utilize radar information from both the TDWR testbed and the operational NEXRAD/WSR-88D radar in Melbourne, Florida. This report documents the implementation of the T-LAPS system that was run during the 1992 summer demonstration and discusses the design and some implementation details of the system.

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.

During the summer of 1988, the Terminal Doppler Weather Radar (TDWR) Operational Test and Evaluation (OT&E) was conducted near Denver, CO. One of the objectives of this test was to assess the performance of the Gust Front Detection and Wind Shift Algorithms (Gust Front Algorithm) to be used in the TDWR system. This paper presents an overview of the Gust Front Algorithm system from data collection to products displays and discusses the performance of the algorithm during the 1988 OT&E. Data editing, product generation, ground truth and scoring issues are addressed. Scoring results for the various products are presented and problems identified during the OT&E are discussed. The design of the Gust Front Algorithm is discussed in the companion paper (Part 1 Current Status) numbered 1.6 in this preprint volume. The Gust Front Algorithm serves two functions: warning and planning. Warnings are provided in alphanumeric messages on a "Ribbon Display Terminal", Wind shear warnings are issued when a gust front impacts the runways or within 3 miles of the ends of the runways. The planning function consists of alerting an Air Traffic Control Supervisor when a change in wind speed and/or direction due to a gust front at the airport will occur within 20 minutes. This planning information is displayed on a Geographic Situation Usplay (GSD).

The gust front detection and wind shift algorithm is one of the two main algorithms developed for the Terminal Doppler Weather Radar (TDWR) program. This two-part paper documents some recent enhancements to, and the current status of, the algorithm (Part 1) and presents some results from recent testing of the algorithm during the TDWR Operational Test and Evaluation (OT&E) (Part 2: Klingle-Wilson et al., 1989).

This paper describes an artificial intelligence-based approach for automated recognition of wind shear hazards. The design of a prototype system for recognizing low-altitude wind shear events from Doppler radar displays is presented. This system, called WXI, consists of a conventional expert system augmented by a specialized capability for processing radar images. The radar image processing component of the system employs numerical and computer vision techniques to extract features from radar data. The expert system carries out symbolic reasoning on these features using a set of heuristic rules expressing meteorological knowledge about wind shear recognition. Results are provided demonstrating the ability of the system to recognize microburst and gust front wind shear events.

This paper describes work performed by M.I.T. Lincoln Laboratory for the Federal Aviation Administration to investigate the use of expert system techniques for weather radar interpretation. The design of WX1, a prototype system for recognizing low-altitude wind shear hazards from Doppler weather radar data, is presented. The WX1 system consists of a rule-based expert system coupled to an object-oriented image processing package. Initial results for recognition of two types of low-altitude wind shear are provided.