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Range-velocity ambiguity mitigation schemes for the enhanced Terminal Doppler Weather Radar
August 6, 2003
Conference Paper
Published in:
37th Int. Conf. on Radar Meteorology, 6-12 August 2003.
Summary
The Terminal Doppler Weather Radar (TDWR) radar data acquisition (RDA) subsystem is being replaced as part of a broader FAA program to improve the supportability of the system. An engineering prototype RDA is under development that will provide a modern, open-systems hardware platform and standards-compliant software. The new platform also provides an opportunity to insert algorithms to improve the quality of existing base data products, as well as support future enhancements to the aviation weather services provided by TDWR. There are several outstanding data quality issues with the TDWR. In this paper, we focus on mitigation schemes for the range-velocity ambiguity problem that is especially severe for C-band weather radars such as the TDWR.
Summary
The Terminal Doppler Weather Radar (TDWR) radar data acquisition (RDA) subsystem is being replaced as part of a broader FAA program to improve the supportability of the system. An engineering prototype RDA is under development that will provide a modern, open-systems hardware platform and standards-compliant software. The new platform also...
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Reducing severe weather delays in congested airspace with weather decision support for tactical air traffic management
June 23, 2003
Conference Paper
Published in:
5th Eurocontrol/DAA ATM R&D Seminar, 23-27 June 2003.
Summary
Reducing congested airspace delays due to thunderstorms has become a major objective of the FAA due to the recent growth in convective delays. In 2000 and 2001 the key new initiative for reducing these convective weather delays was "strategic" traffic flow management (TFM) at time scales between 2 and 6 hours in advance using collaborative weather forecasts and routing strategy development. This "strategic" approach experienced difficulties in a large fraction of the weather events because it was not possible to forecast convective storm impacts on routes and capacities accurately enough to accomplish effective traffic flow management. Hence, we proposed in 2001 that there needed to be much greater emphasis on tactical air traffic management at time scales where it would be possible to generate much more accurate convective weather forecasts. In this paper, we describe initial operational results in the very highly congested Great Lakes and Northeast Corridors using weather products from the ongoing Corridor Integrated Weather System (CIWS) concept exploration. Key new capabilities provided by this system include very high update rates (to support tactical air traffic control), much improved echo-tops information, and fully automatic 2-hour convective forecasts using the latest "scale separation" storm tracking technologies. Displays were provided at major terminal areas, en route centers in the corridors, and the FAA Command Center. Substantial reduction in delays has been achieved mostly through weather product usage at the shorter time scales. Quantifying the achieved benefits for this class of products have raised major questions about the conceptual framework for traffic flow management in these congested corridors that must be addressed in the development of air traffic management systems to utilize the weather products.
Summary
Reducing congested airspace delays due to thunderstorms has become a major objective of the FAA due to the recent growth in convective delays. In 2000 and 2001 the key new initiative for reducing these convective weather delays was "strategic" traffic flow management (TFM) at time scales between 2 and 6...
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Route selection decision support in convective weather: a case study of the effects of weather and operational assumptions on departure throughput
June 23, 2003
Conference Paper
Published in:
5th Eurocontrol/FAA ATM R&D Seminar, 23-27 2003.
Summary
This paper presents a detailed study of a convective weather event affecting the northeastern United States on 19 April 2002: its impacts on departure throughput, the response of traffic managers and an analysis of the potential effects of decision support on system performance. We compare actual departure throughput to what may have been achieved using the Route Availability Planning Tool (RAPT), a prototype decision support tool. We examine two questions: Can decision support identify opportunities to release departures that were missed during the event? How is route selection guidance affected by the operational model incorporated into the decision support tool? By "operational model", we mean three things: the choice of weather forecast information used to define hazards (precipitation, echo tops, etc.), the model for how airspace is used (route definition and allocation) and the assessment of the likelihood that a given route is passable. We focus our analysis on the operational model only; we eliminate weather forecast uncertainty as a factor in the analysis by running RAPT using the actual observed weather as the forecast ('perfect' forecast). Results show that decision support based on perfect forecasts is sensitive to all three elements of the operational model. The sensitivity to weather metrics became evident when we compared decision support based upon perfect forecasts of level 3 vertically integrated liquid (VIL) to that based upon VIL plus storm echo tops. Traffic managers were at times able to move more aircraft by abandoning nominal routing than if they had used nominal routing with perfect weather information. The assessment of route availability will, at times, be ambiguous; different interpretations of that assessment lead to decisions that result in significant differences in departure throughput. These results suggest that for traffic flow management tools, a realistic operational model may be at least as important as the frequently discussed problem of weather forecast uncertainty.
Summary
This paper presents a detailed study of a convective weather event affecting the northeastern United States on 19 April 2002: its impacts on departure throughput, the response of traffic managers and an analysis of the potential effects of decision support on system performance. We compare actual departure throughput to what...
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Multi-radar integration to improve en route aviation operations in severe convective weather
February 12, 2003
Conference Paper
Published in:
19th Int. Conf. of Interactive Info Processing Systems in Meteorology, Oceanography and Hydrology, IIPS, 9-13 February 2003.
Summary
In this paper, we describe a major new FAA initiative, the Corridor Integrated Weather System (CIWS), to improve convective weather decision support for congested en route airspace and the terminals within that airspace through use of a large, heterogeneous network of weather sensing radars as well as many additional sensors. The objective of the CIWS concept exploration is to determine the improvements in NAS performance that could be achieved by providing en route controllers, en route and major terminal traffic flow managers, and airline dispatch with accurate, fully automated high update-rate information on current and near term (0-2 hour) storm locations, severity and vertical structure so that they can achieve more efficient tactical use of the airspace. These "tactical" traffic flow management products will complement the longer-term (2-6 hr) forecasts that are also needed for flight planning and strategic traffic flow management. Since balancing the en route traffic flows in the presence of time varying impacts on sector capacities by convective weather is essential if delays are to be reduced, an important element of the CIWS initiative is interfacing to and, in some cases providing, air traffic flow management (TFM) and airline dispatch decision support tools (DSTs)
Summary
In this paper, we describe a major new FAA initiative, the Corridor Integrated Weather System (CIWS), to improve convective weather decision support for congested en route airspace and the terminals within that airspace through use of a large, heterogeneous network of weather sensing radars as well as many additional sensors...
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A comparison of boundary layer wind estimation techniques
May 13, 2002
Conference Paper
Published in:
10th Conf. on Aviation, Range, and Aerospace Meteorology, 13-16 May 2002, pp. 331-33334.
Summary
Accurate, short-term (0-2 hour) forecasts of convective initiation provide critical information about weather that has a major impact on aviation safety and system capacity. The Terminal Convective Weather Forecast (TCWF) algorithm is a key component of the FAA's operational Integrated Terminal Weather System (ITWS). Convective forecasts rely, in part, upon detection of convergence zones in the boundary layer. Detection of convergence requires accurate, high-resolution wind estimates, which may be based on measurements from many sources, including Terminal Doppler Weather Radar (TDWR), Next Generation Weather Radar (NEXRAD), Automatic Weather Observation System/Automatic Surface Observation System (AWOS/ASOS), aircraft (via the Meteorological Data Collection and Reporting System, MDCRS) and Low Level Wind Shear Alert System (LLWAS). These data may be directly analyzed, combined with satellite and sounding data or ingested into physical models that estimate winds and produce short term forecasts. We compare two windfield estimation techniques: Terminal Winds (TWINDS) [Cole et. al., 2000], an optimal estimation algorithm developed at Lincoln Laboratory that is deployed operationally in ITWS, and Variational Doppler Radar Analysis System (VDRAS) [Sun and Crook, 2001], a 4DVAR algorithm developed and fielded by the Research Applications Program (RAP) at NCAR. These techniques differ markedly in their use of physical models: TWINDS applies no physical constraints to its analysis, while VDRAS uses a 4DVAR technique to fit the data with a boundary layer model as a strong constraint. The techniques also differ in their computational requirements: TWINDS requires substantially less computational power than VDRAS. We were able to run TWINDS at higher horizontal resolution and update rate (1km grid spacing, 5 minute update) than VDRAS (2km and 12 minutes).
Summary
Accurate, short-term (0-2 hour) forecasts of convective initiation provide critical information about weather that has a major impact on aviation safety and system capacity. The Terminal Convective Weather Forecast (TCWF) algorithm is a key component of the FAA's operational Integrated Terminal Weather System (ITWS). Convective forecasts rely, in part, upon...
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A web-based display and access point to the FAA's Integrated Terminal Weather System (ITWS)
May 13, 2002
Conference Paper
Published in:
10th Conf. on Aviation, Range and Aerospace Meteorology, 13-16 May 2002, pp. 206-209.
Summary
The Integrated Terminal Weather System (ITWS) is a high-resolution weather information system designed to operate within the TRACONs surrounding the country's major airports. Targeted for those airports most often adversely affected by convective weather, the system was developed for the Federal Aviation Administration (FAA) by the Massachusetts Institute of Technology's Lincoln Laboratory (MIT/LL) Weather Sensing Group. The ITWS acquires data from Next Generation Radars (NEXRAD), Terminal Doppler Weather Radars (TDWR), Airport Surveillance Radars (ASR-9), Low Level Windshear Alert Systems (LLWAS), the National Lightning Detection Network (NLDN), Automated Weather Observing Stations (AWOS/ASOS), and aircraft in flight. The system integrates the data to provide consistent weather information in a form that is usable without further meteorological interpretation. This information includes six-level precipitation at a number of ranges, windshear and microburst detection and prediction, storm motion and extrapolated position, wind fields, gust fronts, lightning, and storm cell information (hail, mesocyclone notification, and echo tops). A set of direct users of ITWS (FAA users at TRACONs, Air Traffic Control Towers, and en-route centers) will receive ITWS weather products through FAA-provided Situation Displays (SDs) that are tied directly to the ITWS processor. In addition, the FAA has sponsored development of an ITWS External Users Data Distribution System to provide real-time ITWS products to those users who do not have access to a dedicated SD. The data distribution system is being developed in conjunction with the upcoming deployment of the ITWS (2002-2004) as an operational FAA system serving 47 major airports. The need for a remotely accessible display is strongly supported by draft recommendations recently released by the National Transportation Safety Board (NTSB) that call for U.S. air carriers and all air traffic control facilities to have access to data from FAA terminal weather information systems. In addition, the Collaborative Decision Making program (CDM) has highlighted the need to make the information widely available to airlines. MIT/LL has operated demonstration ITWS systems since 1994, and a demonstration website since 1997. Most major airlines have successfully accessed the ITWS demonstration products in real time via Web browsers and have used this information to improve safety and reduce delays (Maloney, 2000). Benefits specific to airline dispatch include support for decisions made during diversion situations and improvements in hub operations . By sharing a common view of the same operational environment, controllers, dispatchers and other aviation decision makers and stakeholders have been better able to understand and coordinate the decisions that affect air traffic in the terminal area and surrounding en route airspace (Evans 2000). This paper describes the goals of the ITWS External Users Data Distribution System development project, including a discussion of the system architecture, data distribution and access methods, and the web-based interface.
Summary
The Integrated Terminal Weather System (ITWS) is a high-resolution weather information system designed to operate within the TRACONs surrounding the country's major airports. Targeted for those airports most often adversely affected by convective weather, the system was developed for the Federal Aviation Administration (FAA) by the Massachusetts Institute of Technology's...
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An automated, operational two hour convective weather forecast for the Corridor Integrated Weather
May 13, 2002
Conference Paper
Published in:
10th Conf. on Aviation, Range and Aerospace Meteorology, 13-16 May 2002, pp. 116-119.
Summary
The FAA Aviation Weather Research Program (AWRP) is an initiative of the Weather and Flight Service Systems Integrated Product Team, AUA400. One of the goals of the AWRP is to create accurate and accessible forecasts of hazardous weather tailored to the needs of the aviation community. Pursuant to this goal, the AWRP has sponsored the collaboration of the Research Applications Program (RAP) of the National Center for Atmospheric Research (NCAR), the Aviation and Forecast Research Divisions at the NOAA Forecast Systems Laboratory (FSL), the Weather Sensing Group of the Massachusetts Institute of Technology's Lincoln Laboratory (MIT/LL) and the National Severe Storm Laboratory (NSSL) on a Product Development Team (PDT). This Convective Weather PDT is developing an automated system that combines real-time weather- radar data with the current "state-of-the-art" convective weather prediction algorithms to produce forecasts of convective weather for the heavily traveled air traffic routes in the Great Lakes/Northeast corridor (Chicago to New York). This Regional Convective Weather Forecast (RCWF) will be provided to traffic flow management decision-makers as part of the proof-of-concept Corridor Integrated Weather System (CIWS), which began operations in July 2001 with a l-hr animated Regional Convective Weather Forecast (RCWF).
Summary
The FAA Aviation Weather Research Program (AWRP) is an initiative of the Weather and Flight Service Systems Integrated Product Team, AUA400. One of the goals of the AWRP is to create accurate and accessible forecasts of hazardous weather tailored to the needs of the aviation community. Pursuant to this goal...
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An improved gust front detection capability for the ASR-9 WSP
May 13, 2002
Conference Paper
Published in:
10th Conf. on Aviation, Range, and Aerospace Meteorology, 13-16 May 2002, pp. 379-382.
Summary
The Weather Systems Processor (WSP) is being deployed by FAA at 35 medium and high-density ASR-9 equipped airports across the United States. The Machine Intelligent Gust Front Algorithm (MIGFA) developed at Lincoln Laboratory provides important gust front detection and tracking capability for this system as well as other FAA systems including Terminal Doppler Weather Radar (TDWR) and Integrated Terminal Weather System (ITWS). The algorithm utilizes multidimensional image processing, data fusion, and fuzzy logic techniques to recognize gust fronts observed in Doppler radar data. Some deficiencies in algorithm performance have been identified through ongoing analysis of data from two initial limited production WSP sites in Austin, TX (AUS) and Albuquerque, NM (ABQ). At AUS, the most common cause of false alarms is bands of low-reflectivity rain echoes having shapes and intensities similar to gust front thin line echoes. Missed or late detections have occasionally occurred when gust fronts are near or embedded in the leading edge of approaching line storms, where direct radar evidence of the gust front (e.g.. thin line echo, velocity convergence) may be fragmented or absent altogether. In ABQ, "canyon wind" events emanating, from mountains located just east of the airport occur with very little lead time, and often with little or no radar signatures, making timely detection on the basis of the radar data alone difficult. MIGFA is equipped with numerous parameters and thresholds that can be adjusted dynamically based on recognition of the local or regional weather context in which it is operating. Through additional contextual weather information processing, this dynamic sensitization capability has been further exploited to address the deficiencies noted above, resulting in an appreciable improvement in performance on data collected at the two WSP sites.
Summary
The Weather Systems Processor (WSP) is being deployed by FAA at 35 medium and high-density ASR-9 equipped airports across the United States. The Machine Intelligent Gust Front Algorithm (MIGFA) developed at Lincoln Laboratory provides important gust front detection and tracking capability for this system as well as other FAA systems...
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Aircraft encounters with thunderstorms in enroute vs. terminal airspace above Memphis, Tennesssee
May 13, 2002
Conference Paper
Published in:
Proc. 10th Conf. on Aviation, Range and Aerospace Meteorology, 13-16 May 2002, pp. 162-165.
Summary
To date, very little attention has been given to quantifying the effects of thunderstorms on air traffic in enroute airspace. What types of storms cause pilots to deviate from their nominal flight routes? What types of storms do pilots fly through? Around? Over? When thunderstorms are forecast to affect a particular region, how many planes will need to be rerouted? Which ones? Which aspects of the storm need to be accurately forecast in order to answer those questions? How does the forecast accuracy affect the quality of airspace capacity predictions? Quantitative answers to these questions would contribute to the design of useful decision support tools. Federal Aviation Administration decision support tools are being equipped with the ability for air traffic managers to define dynamic "flow constrained areas" (FCAs). Each FCA will be a polygon in latitude/longitude space with ceiling and floor altitudes and a motion vector. One primary use for FCAs will be to define regions that do, or probably will, contain convective thunderstorm activity. These tools will help air traffic managers decide which planes to re-route around the weather and which planes have a reasonable chance of flying through, between, or over the storms. Although it will be helpful to have the ability to manually define FCAs in the traffic managers' tools, the efficiency of the solutions that will be worked out with those tools would be greatly enhanced by answers to the questions posed above. In our prior work we have attempted to quantify the behavior of pilots who encounter thunderstorms in terminal airspace during the final 60 nautical miles of flight. In this study we compare the storm avoidance behavior of pilots in enroute airspace with that of pilots who encountered the very same storms at lower altitudes, in terminal airspace. The study is preliminary, but it complements the terminal work, affords some insight into pilot behavior, and raises questions that should be addressed in a larger study.
Summary
To date, very little attention has been given to quantifying the effects of thunderstorms on air traffic in enroute airspace. What types of storms cause pilots to deviate from their nominal flight routes? What types of storms do pilots fly through? Around? Over? When thunderstorms are forecast to affect a...
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An evaluation of the Medium-Intensity Airport Weather System (MIAWS) products at the Memphis, TN and Jackson, MS International Airports
May 13, 2002
Conference Paper
Published in:
10th Conf. on Aviation, Range, and Aerospace Meteorology (13th Conf. on Applied Climatology), 13-16 May 2002, pp. J118-J122.
Summary
The FAA is procuring aviation weather systems, which are designed to enhance safety/capacity and reduce delays at U.S. airports. The two most widely publicized systems currently being installed are the Integrated Terminal Weather System (ITWS) at airports equipped with a Terminal Doppler Weather Radar (TDWR) and the Weather System Processor (WSP) at those terminal areas covered by an Airport Surveillance Radar, Model 9 (ASR-9). At airports not slated to receive either an ITWS or WSP, an emerging system coined the Medium Intensity Airport Weather System (MIAWS) will be installed. Currently, either an ASR-7 or 8 provides terminal aircraft surveillance at these airports. Unfortunately, these platforms do not output calibrated precipitation intensity or storm motion information. Quantitative six-level weather reflectivity data will be available once the digitally enhanced ASR-11 radar system is operational at MIAWS supported sites. The Low Level Wind Shear Alert System - Relocation/Sustainment (LLWAS-RS) anemometer network will provide MIAWS with surface-based winds and wind shear alerts. The rationale for MIAWS evolved from the ITWS and WSP prototype testing. The premise is that the calibrated reflectivity and velocity data from state-of-the-art radar platforms can be utilized to produce a suite of current and forecasted storm positions to aid air traffic control decision making. The forecasted location is a critical issue if the storms are moving rapidly. This can lead to a scenario where the weather conditions deteriorate significantly within a matter of minutes. Once implemented, MIAWS will be an essential component of the National Airspace System by providing this evolving technology to airports whose traffic counts are not sufficient to warrant either an ITWS or WSP, but where commercial carriers could reap the benefits of a high-quality weather radar system. The FAA has contracted the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL) to undertake a proof-of-concept evaluation of MIAWS. To this end, MIT/LL installed two prototype systems at the Jackson, MS (JAN) and Memphis, TN (MEM) International Airports. The system at MEM is used solely for product evaluation and refinement, while the FAA is operationally evaluating the JAN MIAWS. The focus of this report is a preliminary assessment of the capabilities and limitations of MIAWS in its current implementation, i.e. precipitation based solely on NEXRAD data. Potential enhancements to the NEXRAD product data and MIAWS algorithms will also be discussed.
Summary
The FAA is procuring aviation weather systems, which are designed to enhance safety/capacity and reduce delays at U.S. airports. The two most widely publicized systems currently being installed are the Integrated Terminal Weather System (ITWS) at airports equipped with a Terminal Doppler Weather Radar (TDWR) and the Weather System Processor...
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