Publications
A description of the interfaces between the Weather Systems Processor (WSP) and the Airport Surveillance Radar (ASR-9)
June 16, 1997
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-259
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Summary
The Weather Systems Processor (WSP) is an enhancement for the Federal Aviation Administration's (FAA) current generation Airport Surveillance Radars (ASR-9) that provides fully automated detection of microburst and gust front wind shear phenomena, estimates of storm cell movement and extrapolated future postion, and 10- and 20-minute predictions of the future postion of gust fronts. The WSP also generates six-level weather reflectivity free of anomalous propagation induced ground clutter breakthrough. Alphanumeric and graphical displays provide WSP-generated weather information to air traffic controllers and their supervisors. This report describes the hardware, interfaces, timing and digital signal extraction from the ASR-9 necessary to support the WSP. The digital interface circuitry between the WSP and the ASR-9, the control functions associated with the WSP, and the strategies for performing system test functions are described
Summary
The Weather Systems Processor (WSP) is an enhancement for the Federal Aviation Administration's (FAA) current generation Airport Surveillance Radars (ASR-9) that provides fully automated detection of microburst and gust front wind shear phenomena, estimates of storm cell movement and extrapolated future postion, and 10- and 20-minute predictions of the future...
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Low altitude wind shear detection using airport surveillance radars
March 29, 1994
Conference Paper
Published in:
Proc. 1994 IEEE Natl. Radar Conf., 29-31 March 1994, pp. 52-57.
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Summary
This paper describes an enhanced weather processor for the Federal Aviation Administration's Airport Surveillance Radar (ASR-9) that will include Doppler wind estimation for the detection of low altitude wind shear, scan-to-scan tracking to provide estimates of the speed and direction of storm movement and suppression' of spurious weather reports currently generated by the ASR-9's six-level weather channel during episodes of anomalous radar energy propagation (AP). This ASR-9 Wind Shear Processor (WSP) will be implemented as a retrofit to the ASR-9 through the addition of interfaces, receiving chain hardware and high-speed digital processing and display equipment. Thunderstorm activity in terminal airspace (the volume extending approximately 30 nmi from an airport and to 15,000 feet altitude) is an obvious safety issue and makes a significant overall contribution to delay in the United States commercial aviation industry. Analysis and on-line testing of the prototype ASR-9 WSP has confirmed that the system can provide operationally beneficial detection of low-altitude wind shear phenomena and enhanced weather situational awareness for Air Traffic Control teams.
Summary
This paper describes an enhanced weather processor for the Federal Aviation Administration's Airport Surveillance Radar (ASR-9) that will include Doppler wind estimation for the detection of low altitude wind shear, scan-to-scan tracking to provide estimates of the speed and direction of storm movement and suppression' of spurious weather reports currently...
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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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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 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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Anomalous propagation associated with thunderstorm outflows
May 24, 1993
Conference Paper
Published in:
Proc. 26th Int. Conf. on Radar Meteorology, 24-28 May 1993, pp. 238-240.
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Summary
Battan noted that ducting of radar energy by anomalous atmospheric refractive index profiles and resulting abnormally strong ground clutter can occur during three types of meteorological circumstance: (i) large scale boundary layer temperature inversions and associated sharp decrease in moisture with height -- these are often created by nocturnal radiative cooling; (ii) warm, dry air moving over cooler bodies of water, resulting in cooling and moistening of air in the lowest levels; (iii) cool, moist outflows from thunderclouds. In contrast to the first two types of anaomalous propagation (AP), radar ducting associated with thunderstorm outflows is quite dynamic and may mimic echoes from precipitating clouds in terms of spatial scale and temporal evolution. While non-coherent weather radars (e.g. WSR-57) are obviously susceptible to false storm indications from this phenomemenon, Doppler radars that select the level of ground clutter suppression based on "clear day maps" may also fail to suppress the AP-induced ground clutter echoes. Operational Doppler radar systems known to be susceptible to this phenomena are the National Weather Service's WSR-88D and the Federal Aviation Administration's Airport Surveillance Radar (ASR-9) six-level weather channel. In this paper, characteristics of thunderstorm outflow-generated AP are documented using data from a testbed ASR-9 operated at Orlando, Florida. The testbed radar's rapid temporal update (4.8 seconds per PPI scan) and accurate scan-to-scan registration of radar resolution cells enabled characterization of the spatial and temporal evolution of the AP-induced clutter echoes. We discuss implications of these phenomenological characteristics on operational systems, specifically the ASR-9. Algorithms for discrimination between true precipitation echoes and AP-induced ground clutter are discussed.
Summary
Battan noted that ducting of radar energy by anomalous atmospheric refractive index profiles and resulting abnormally strong ground clutter can occur during three types of meteorological circumstance: (i) large scale boundary layer temperature inversions and associated sharp decrease in moisture with height -- these are often created by nocturnal radiative...
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Microburst detection with airport surveillance radars
August 1, 1989
Conference Paper
Published in:
34th Ann. Air Traffic Control Associsation., 30 October 1989 - 2 November 1989, pp. 514-522.
Summary
With the advent of fully digital signal processing for new airport surveillance radars (ASR-9), terminal air traffic control displays will be largely free of clutter from precipitation and ground scatterers [1,2]. Early acceptance testing of the ASR-9, however, indicated that working air traffic controllers actually made considerable use of the weather echo information on their displays. To reinsert weather data in a non-interfering manner, the ASR-9's signal processor was augmented with a dedicated channel for processing and displaying six quantitative levels of precipitation reflectivity (i.e. rain rate) [2,3]. This processor does not utilize tile radar's coherency, other than for Doppler filtering of ground clutter echoes. In this paper, we describe processing techniques that would allow airport surveillance radars to extend their weather measurement capability to the detection of microburst-generated low altitude wind shear. The two principal technical challenges are the development of (i) signal processing to suppress ground clutter and estimate the near surface radial wind component in each radar resolution cell; (ii) image processing to automatically detect hazardous shear in the resulting velocity field. The techniques have been evaluated extensively using simulated weather signals and measurements from an experimental airport surveillance radar in the southeastern United States. Overall our analysis indicates that microbursts accompanied by rain at the surface -- the predominant safety hazard in many parts of the U.S. --could be detected with high confidence using a suitably modified ASR. In the following section we describe briefly the background and potential operational role of an ASR-based wind shear detection system. We then discuss the primary technical issues for achieving this capability and our evaluations of processing methods that address these issues.
Summary
With the advent of fully digital signal processing for new airport surveillance radars (ASR-9), terminal air traffic control displays will be largely free of clutter from precipitation and ground scatterers [1,2]. Early acceptance testing of the ASR-9, however, indicated that working air traffic controllers actually made considerable use of the...
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Advances in primary-radar technology
January 1, 1989
Journal Article
Published in:
Lincoln Laboratory Journal, Vol. 2, No. 3, Fall 1989, pp. 363-380.
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Summary
Current primary radars have difficulty detecting aircraft when ground clutter, rain, or birds interfere. To overcome such interference, the Moving Target Detector (MTD) uses adaptive digital signal and data processing techniques. MTD has provided the foundation for a new generation of primary radars called Airport Surveillance Radar-9 (ASR-9). In addition to achieving near-optimal target-detection performance, ASR-9 also provides timely weather information. The Federal Aviation Administration (FAA) is installing ASR- 9 systems at more than 100 airports across the United States.
Summary
Current primary radars have difficulty detecting aircraft when ground clutter, rain, or birds interfere. To overcome such interference, the Moving Target Detector (MTD) uses adaptive digital signal and data processing techniques. MTD has provided the foundation for a new generation of primary radars called Airport Surveillance Radar-9 (ASR-9). In addition...
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