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Microburst recognition: an expert system approach

September 26, 1986
  |
Conference Paper
Author:
Steven D. Campbell
Published in:
Proc. 23rd Conf. on Radar Meteorology, Vol. 1, 22-26 September 1986, pp. 26-29.
Topic:
weather
R&D area:
R&D group:

Summary

Expert systems have gained much recent attention as a means for capturing the performance of human experts in specialized fields of knowledge. Areas in which expert systems have been successfully developed include such varied applications as mass spectrogram interpretation, disease diagnosis, geological data analysis and computer configuration (Hayes-Roth et al, 1983). The assumption behind these applications is that a body of specialized knowledge is possessed by the human expert. Expert systems attempt to capture this knowledge in an explicit form, each as a set of heuristic rules, and employ mechanisms to apply this knowledge to solve problems in the domain of expertise. Using this approach, expert systems have been able to successfully perform tasks which previously could only be carried out by human specialists. Moreover, expert systems have in some cases been able to attain levels of performance equaling that of humans (Buchanan and Shortliffe, 1984). This paper describes an expert system-based approach to the problem of recognizing microbursts from Doppler weather radar data. A prototype system based on this approach is currently being developed at Lincoln Laboratory for automated recognition of low-altitude wind shear hazards. This system, called WX1, employs artificial intelligence and computer vision techniques to emulate the symbolic reasoning and visual processing capabilities of a radar meteorologist.
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Summary

Expert systems have gained much recent attention as a means for capturing the performance of human experts in specialized fields of knowledge. Areas in which expert systems have been successfully developed include such varied applications as mass spectrogram interpretation, disease diagnosis, geological data analysis and computer configuration (Hayes-Roth et al...

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Microburst recognition: an expert system approach

An automatic weather station network for low-altitude wind shear investigations

September 18, 1984
  |
Project Report
Author:
Diana L. Klingle-Wilson
…
Published in:
MIT Lincoln Laboratory Report ATC-128
Topic:
weather
R&D area:
R&D group:

Summary

During the summer of 1983 an experimental network of automatic weather stations (a mesonet) was operated in the vicinity of Hanscom Field, northwest of Boston, as part of a larger effort to collect Doppler radar and meteorological data on thunderstorms and other potentially hazardous weather events in this area. This report describes the mesonet system used and presents in detail the data collected on 21-22 July 1983. Conclusions about the limitations and the future use of the mesonet system are also included.
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Summary

During the summer of 1983 an experimental network of automatic weather stations (a mesonet) was operated in the vicinity of Hanscom Field, northwest of Boston, as part of a larger effort to collect Doppler radar and meteorological data on thunderstorms and other potentially hazardous weather events in this area. This...

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An automatic weather station network for low-altitude wind shear investigations

A comparison of storm tracking and extrapolation algorithms

July 31, 1984
  |
Project Report
Author:
John C. Brasunas
Published in:
MIT Lincoln Laboratory Report ATC-124
Topic:
weather
R&D area:
R&D group:

Summary

The FAA requires short-term forecasts of the development and motion of high reflectivity regions to plan for weather avoidance in the en route and terminal areas. Specific needs include choice of air routes and anticipating when to open or close approach/departure gates, descent corridors, and runways. This report compares storm-tracking algorithms for making short-term (0-30 minute) forecasts of high reflectivity areas, to serve these air traffic control needs. The area forecasts are made by moving the key features of the current reflectivity map according to the velocities derived from the storm trackers. The NEXRAD centroid, correlation, and Crane peak-cell trackers are compared against themselves, persistence, and a best-fit extrapolation. Two performance measures are used: (a) overlap of predicted versus actual areas (b) accuracy in flight-path choice. The second method is a new way of scoring the predictor performance and is particularly suited to aviation needs. Five storms are considered, three in Massachusetts and two in Oklahoma. The correlation and peak-cell trackers generally performed well in the Massachusetts storms, close to a best correlation fit extrapolator. The centroid tracker behaves erratically, due to contour merging and splitting. The centroid tracker performed well on compact, Oklahoma storms where the correlation and peak-cell trackers were misled by storm propagation, an effect to be expected when there is high vertical shear of the horizontal wind. It is recommended that either the correlation or centroid tracker be used, depending on the type of storm expected. The centroid tracker would be used on compact storms; the correlation tracker would be used on storms without substantial propagation. The forecasts appear to be skillful in predicting high-reflectivity areas; however, they are less skillful in anticipating flight-paths which do not intersect these areas. Inclusion of forecasts of storm growth and decay will probably be required to improve the performance; anticipating growth and decay will also be important for forecasts of greater than 30 minutes.
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Summary

The FAA requires short-term forecasts of the development and motion of high reflectivity regions to plan for weather avoidance in the en route and terminal areas. Specific needs include choice of air routes and anticipating when to open or close approach/departure gates, descent corridors, and runways. This report compares storm-tracking...

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A comparison of storm tracking and extrapolation algorithms

Rain rate climatologies over marine regions

May 1, 1984
  |
Project Report
Author:
Andreas K. Goroch
…
Published in:
no published logic to cover case - index 63
Topic:
weather
R&D area:
R&D group:

Summary

A method to relate archived marine meteorological observations to two-minute average rain rates is described. The method is used to produce maps that indicate the frequency of observation of critical rain rates (5, 8, and 15 mm/hr) for the Atlantic, North Pacific and Indian Oceans.
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Summary

A method to relate archived marine meteorological observations to two-minute average rain rates is described. The method is used to produce maps that indicate the frequency of observation of critical rain rates (5, 8, and 15 mm/hr) for the Atlantic, North Pacific and Indian Oceans.

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Rain rate climatologies over marine regions

FAA weather surveillance requirements in the context on NEXRAD

November 19, 1982
  |
Project Report
Author:
Bruce G. Laird
…
Published in:
MIT Lincoln Laboratory Report ATC-112
Topic:
radar
R&D area:
R&D group:

Summary

The Federal Aviation Administration (FAA), National Weather Service and Air Force Weather Service are currently engaged in a program to develop a next generation of weather radars (NEXRAD) capable of satisfying (to the greatest extent possible) the common weather information needs of these agencies. This report identifies the unique FAA weather radar surveillance requirements and examines the technical issues that arise in attempting to meet these requirements with the NEXRAD strawman radar sensors and siting. Current air traffic control (ATC) weather data usage and statistics of aviation weather hazards and system efficiency are used to prioritize products needed for ATC. The strawman NEXRAD capability is then reviewed in the context of the identified weather products and factors such as: (1) effects of front end noise and weather return statistics (2) resolution and low altitude coverage constraints (3) the clutter environment associated with various siting options, and (4) data quality required for real time automated display of hazardous weather regions to ATC controllers. It is concluded that significant problems will arise in attempting to simultaneously provide terminal and en route weather surveillance by a single radar as envisioned in the NEXRAD strawman. An analytical/experimental research and development program is described to resolve the identified technical uncertainties in the NEXRAD strawman design for FAA applications. The suggested research and development program includes an operationally oriented interactive data gathering program to evaluate weather products at an ARTCC and TRACON using existing pencil beam S-band radars (e.g., similar to that at MIT) to be followed by similar evaluations in other key geographical areas (e.g., the southeast) using a transportable testbed. Both radar systems would incorporate special features to minimize the likelihood of false targets (e.g., due to obscuration and/or clutter) as well as automated display and short term prediction of hazardous weather regions for use by ATC controllers.
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Summary

The Federal Aviation Administration (FAA), National Weather Service and Air Force Weather Service are currently engaged in a program to develop a next generation of weather radars (NEXRAD) capable of satisfying (to the greatest extent possible) the common weather information needs of these agencies. This report identifies the unique FAA...

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FAA weather surveillance requirements in the context on NEXRAD

En route weather data extraction from ATC radar systems

March 11, 1982
  |
Project Report
Author:
David Karp
Published in:
MIT Lincoln Laboratory Report ATC-113
Topic:
radar
R&D area:
R&D group:

Summary

This report describes the results of phase I of the En Route Radar Weather Program. The objective of this effort was to develop techniques for generating accurate en route weather reflectivity estimates in the presence of ground clutter. A candidate weather data extraction processor is proposed for use with either the ASR-MTD or ARSR-MTD radar systems. Principal features of the candidate processor include: (1) an antenna port (to permit use of an appropriate polarization), front end (with R^-2 STC) and quadrature video sampling subsystem which are separate from that used for aircraft surveillance. (2) use of a ground clutter map to select the form of clutter rejection to be used in each individual range-azimuth cell to estimate various weather reflectivity levels, and (3) spatial /temporal smoothing of the cell reflectivity estimates. The key elements of the suggested signal processing techniques were evaluated using data from MTD tests in Bedford, VA, Burlington, VT, and Atlantic City, NJ; however, the full system has not as yet received design validation/refinement and operational evaluation by ATC controllers. In particular, methods for identifying second trip weather echos should be addressed in the full system validation program.
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Summary

This report describes the results of phase I of the En Route Radar Weather Program. The objective of this effort was to develop techniques for generating accurate en route weather reflectivity estimates in the presence of ground clutter. A candidate weather data extraction processor is proposed for use with either...

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En route weather data extraction from ATC radar systems

Coordinated radar and aircraft observations of turbulence

May 26, 1981
  |
Project Report
Author:
Melvin Labitt
Published in:
MIT Lincoln Laboratory Report ATC-108
Topic:
weather
R&D area:
R&D group:

Summary

Interim results of a program to measure and correlate radar- and aircraft-sensed turbulence in rainstorms are presented. The dissipation factor of a turbulence air mass can be measured by an aircraft and a weather radar. Comparisons are made between precipitation reflectivity and spectral width measurements as indicators of turbulence. The instrumentation and data processing procedures are described. Examples of turbulence observations made with a storm-penetrating aircraft and the weather radar are given. The relationship between the radar observations and the physical properties of the turbulence atmosphere are derived. The relationship of radar spectral width (variance) to turbulence intensity is discussed.
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Summary

Interim results of a program to measure and correlate radar- and aircraft-sensed turbulence in rainstorms are presented. The dissipation factor of a turbulence air mass can be measured by an aircraft and a weather radar. Comparisons are made between precipitation reflectivity and spectral width measurements as indicators of turbulence. The...

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Coordinated radar and aircraft observations of turbulence

Format for DABS data link applications

July 30, 1980
  |
Project Report
Author:
John L. Leeper
…
Published in:
MIT Lincoln Laboratory Report ATC-96
Topic:
surveillance
R&D area:
R&D group:

Summary

The purpose of this paper is to describe formats developed for transmitting aviation-related messages over the Discrete Address Beacon System (DABS) data link. Initial data link applications include: (1) Minimum Safe Altitude Warning (MSAW) alerts (Terminal Area) (2) Takeoff Clearance Confirmation (3) Altitude Assignment Clearance Confirmation (Enroute) (4) Weather Reports (a) Surface Observations (b) Terminal Forecasts (c) Pilot Reports (d) Winds Aloft (e) Hazardous Weather Advisories (f) Digitized Weather Radar Maps (5) Enhanced terminal Information Service (ETIS) (6) Downlink of Airborne Measurements. The formats described in this paper cover the DABS communications formats for uplink messages from the DABS sensor to the airborne data link system, and the downlink messages from the aircraft. Downlink messages include pilot requests for routine weather information and ETIS service, pilot acknowledgements for uplink tactical messages, and airborne measurements.
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Summary

The purpose of this paper is to describe formats developed for transmitting aviation-related messages over the Discrete Address Beacon System (DABS) data link. Initial data link applications include: (1) Minimum Safe Altitude Warning (MSAW) alerts (Terminal Area) (2) Takeoff Clearance Confirmation (3) Altitude Assignment Clearance Confirmation (Enroute) (4) Weather Reports...

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Format for DABS data link applications

Radar detection of thunderstorm hazards for air traffic control volume II: radar systems

October 7, 1976
  |
Project Report
Author:
Steven M. Sussman
Published in:
MIT Lincoln Laboratory Report ATC-67,II
Topic:
weather
R&D area:
R&D group:

Summary

Radar systems are investigated for the acquisition of weather data to support detection and forecasting of hazardous turbulence associated with individual storm cells. Utilization of the FAA Airport Surveillance Radar (ASR) is explored. The issues of antenna polarization and Sensitivity Time Control (STG) that impact on shared operation for aircraft and weather detection are addressed. Candidate system configurations employing a common RF channel and dual orthogonal polarization channels are discussed. Ground clutter discrimination by coherent Doppler and noncoherent (Doppler spread) processing methods is described. An interim procedure is suggested for obtaining fixed reflectivity contour data from a Moving Target Detector for use in the all-digital ARTS. A preliminary design is presented for a new joint-use, long-range weather radar to support enroute air traffic controllers and to meet the data requirements of the National Weather Service and the Air Weather Service.
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Summary

Radar systems are investigated for the acquisition of weather data to support detection and forecasting of hazardous turbulence associated with individual storm cells. Utilization of the FAA Airport Surveillance Radar (ASR) is explored. The issues of antenna polarization and Sensitivity Time Control (STG) that impact on shared operation for aircraft...

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Radar detection of thunderstorm hazards for air traffic control volume II: radar systems

Radar detection of thunderstorm hazards for air traffic control volume I: storm cell detection

October 7, 1976
  |
Project Report
Author:
Robert K. Crane
Published in:
MIT Lincoln Laboratory Report ATC-67,I
Topic:
weather
R&D area:
R&D group:

Summary

A procedure was developed to detect hazardous regions within thunderstorms using weather radar data. The procedure is based upon the hypothesis that convective turbulence occurs within 2-3 km of relative radar reflectivity maxima (cells). The hypothesis was tested using a limited set of simultaneous aircraft and radar data. Good agreement was found between the observed regions of convective turbulence and the cell locations determined by radar. The viability of the hazard detection hypothesis as a basis for automatic warning and forcast depends upon the reliability of the cell detection and tracking algorithms. Analysis of precision radar data revealed that the cells are small in area extent, have a detection probability in excess of 0.9 using multiple radar scans, and are readily tracked for periods between 10 and 20 minutes. The characteristics of radar systems for acquiring data to support cell detection, are discussed. The role of Doppler spectral data is explored, and it is found that practical limitations on radar beamwidth hamper direct observation of turbulence on the scale size hazardous to aircraft.
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Summary

A procedure was developed to detect hazardous regions within thunderstorms using weather radar data. The procedure is based upon the hypothesis that convective turbulence occurs within 2-3 km of relative radar reflectivity maxima (cells). The hypothesis was tested using a limited set of simultaneous aircraft and radar data. Good agreement...

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Radar detection of thunderstorm hazards for air traffic control volume I: storm cell detection
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