Publications
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.
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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
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Proc. 10th Conf. on Aviation, Range and Aerospace Meteorology, 13-16 May 2002, pp. 162-165.
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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.
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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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Development of automated aviation weather products for ocean/remote regions: scientific and practical challenges, research strategies, and first steps
May 13, 2002
Conference Paper
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10th Conf. on Aviation, Range, and Aerospace Meteorology, 13-16 May 2002, pp. 57-60.
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From the common and recognizable occurrence of convection, to the sporadic and far less visible reach of volcanic ash, meteorological phenomena impose diverse challenges to the efficiency, economic viability, and safety of flight operations across the global oceans. Those challenges are compounded by special difficulties associated with nowcasting and forecasting for remote areas, such as expansive voids in surface observations and soundings, large forecast domains, communications difficulties, and long-duration flights often needing significant forecast updates. Conspicuously lacking over oceans are the observational capabilities that provide key information about the internal structure of convection - notably radar and lightning detection systems. The long-term oceanic weather development program (OW) outlined here seeks to use improved understanding of the phenomenology of oceanic weather hazards along with new observations, model information and processing tools to fashion automated forecast/briefing products supporting remote oceanic routes. A parallel OW objective (outlined by Lindholm and Bums, 2002, this conference volume) supports in-flight product transfer to the cockpit. Established in March, 2001, the OW program is still in its infancy. Thus, we concentrate here upon strategy and the scientific basis for our plans. Although our work has begun with a focus on low and middle latitudes (Pacific, Atlantic and Gulf of Mexico regions), increasing use of polar routes is likely to raise the priority for products tailored to high latitude regions over the next several years.
Summary
From the common and recognizable occurrence of convection, to the sporadic and far less visible reach of volcanic ash, meteorological phenomena impose diverse challenges to the efficiency, economic viability, and safety of flight operations across the global oceans. Those challenges are compounded by special difficulties associated with nowcasting and forecasting...
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Enhancement to Terminal Doppler Weather Radar to improve aviation weather services
May 13, 2002
Conference Paper
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10th Conf. on Aviation, Range, and Aerospace Meteorology, 13-16 May 2002, pp. 28-31.
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This paper has described work underway to enhance the TDWRs capability to provide wind shear detection services in challenging conditions, and to provide a flexible platform with COTS hardware that would support future improvements. A Radar Data Acquisition (RDA) system retrofit will upgrade the transmitter, receiver and digital signal processing subsystems of the radar to improve the quality of the reflectivity and Doppler imagery generated by the system and to extend its instrumented range. Algorithms have been described for achieving improved rejection of ground clutter and range-folded weather echoes, and reduction of Doppler velocity aliasing. An open COTS-based processing architecture was presented for the TDWR RDA retrofit, and a test program was outlined that is commencing in Oklahoma in the spring of 2002.
Summary
This paper has described work underway to enhance the TDWRs capability to provide wind shear detection services in challenging conditions, and to provide a flexible platform with COTS hardware that would support future improvements. A Radar Data Acquisition (RDA) system retrofit will upgrade the transmitter, receiver and digital signal processing...
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Forecasting convective weather using multi-scale detectors and weather Classification - enhancements to the MIT Lincoln Laboratory Terminal Weather Forecast
May 13, 2002
Conference Paper
Published in:
10th Conf. on Aviation, Range, and Aerospace Meteorology, 13-16 May 2002, pp. 132-135.
Summary
Over the past decade the United States has seen drastic increases in air traffic delays resulting in enormous economic loses. Analysis shows that more then 50% of air traffic delays are due to convective weather. In response the FAA has assembled scientific and engineering teams from MIT Lincoln Laboratory, NCAR. NSSL, FSL and several universities to develop convective weather forecast systems to aid air traffic managers in delay reduction. A user-needs study conducted by Lincoln Laboratory identified that a major source of air traffic delay was due to line thunderstorms (Forman et al., 1999). Recognizing that the line storm envelope motion was distinct from the local cell motion was the impetus for developing the Growth and Decay Storm Tracker' (Wolfson et al., 1999). The algorithm produces forecasts by extracting large-scale features from two dimensional precipitation images. These images are tracked, using either correlation techniques (Terminal Convective Weather Forecast or TCWF) or centroid techniques (National Convective Weather Forecast or NCWF). In TCWF, the track vector field is used to advect the current precipitation images formed to produce a series of forecasts into minute increments up to 60 minutes. The TCWF forecasts are highly skilled for large scale persistent line storms. However, detailed performance analysis of the algorithm has shown that in cases dominated by airmass storms, the algorithm occasionally performed poorly (Theriault et al., 2001). In this paper we describe the sources of error discovered in the TCWF algorithm during the Memphis 2000 performance evaluation, and describe recent enhancements designed to address these problems.
Summary
Over the past decade the United States has seen drastic increases in air traffic delays resulting in enormous economic loses. Analysis shows that more then 50% of air traffic delays are due to convective weather. In response the FAA has assembled scientific and engineering teams from MIT Lincoln Laboratory, NCAR...
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Operational Experience with TDWR/LLWAS-NE Integration at the Dallas, TX International Airport (DFW)
May 13, 2002
Conference Paper
Published in:
10th Conf. on Aviation, Range and Aerospace Meteorology, 13-16 May 2002, pp. 391-394.
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At nine major airports, both the Terminal Doppler Weather Radar (TDWR) and Network Extension of the Low-Level Wind shear Advisory System (LLWAS-NE) data will be used to detect and warn Air Traffic Control (ATC) of dangerous wind shear conditions. The integration of wind shear alerts from the two systems is currently being carried out by the TDWR software and will be accomplished by Integrated Terminal Weather System (ITWS) software when the ITWS is installed at these airports. Previous studies of the performance of the TDWR/LLWAS-NE integrated system were carried out at Denver, CO, Dallas, and Orlando, FL. Additionally, there have been recent concerns about false alarms with the LLWAS-NE. In this study, we examine the performance of the integrated system at Dallas-Ft. Worth International Airport (DFW) over a 6-month period in 2000 with particular emphasis on integrated wind shear alerts produced during a number of cases where the TDWR had difficulty making detections due to: 1. radially aligned gust fronts over DFW, 2. radially aligned divergent features, divergence behind gust fronts and divergence embedded within gravity waves, and/or 3. TDWR radome attenuation or excessively aggressive clutter residue editing. DFW is a particularly good airport for such a study because there is an additional TDWR [for Dallas Love airport (DAL)] located in close proximity to DFW and situated in such a way that it provides a very good viewing angle for wind shear events that may not be well characterized by the DFW TDWR radial velocity data. DFW is also an ITWS demonstration system test site with trained meteorologists who review the wind shear detection performance after all convective weather events at DFW.
Summary
At nine major airports, both the Terminal Doppler Weather Radar (TDWR) and Network Extension of the Low-Level Wind shear Advisory System (LLWAS-NE) data will be used to detect and warn Air Traffic Control (ATC) of dangerous wind shear conditions. The integration of wind shear alerts from the two systems is...
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The Corridor Integrated Weather System (CIWS)
May 13, 2002
Conference Paper
Published in:
10th Conf. on Aviation, Range, and Aerospace Meteorology, 13-16 May 2002, pp. 210-215.
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The FAA Operational Evolution Plan (OEP) identified en route severe weather as one of the four problems that must be addressed if the US. air transportation system is to alleviate the growing gap between the demand for air transportation and the ability of the system to meet that demand. Convective weather in highly congested airspace is of particular concern because many of the delays arise from these corridors. For example, rerouting aircraft around areas of actual or predicted weather can be very difficult when one must be concerned about controller overload in the weather free sectors. When major terminals also underlie the en route airspace, convective weather has even greater adverse impacts. The principal thrust to date in addressing this problem has been "strategic" collaborative routing as exemplified by the "Spring 2000" and "Spring 2001" initiatives. However, success of the strategic approach embodied in these initiatives depends on the ability to accurately forecast convective weather impacts two or more hours in advance. Limitations in the forecast accuracy necessitate development of a companion "tactical" convective weather capability. In this paper, we describe a major new FAA initiative, the Corridor Integrated Weather System (CIWS). The objective of this project, which is currently in the concept exploration phase, is to improve tactical convective weather decision support for congested en route airspace. A real time operational demonstration, which was begun in July 2001 in the Great Lakes corridor, will be extended to the Northeast corridor in 2002. In the sections that follow, we describe the operational needs that motivated the ClWS initiative, the technology under investigation, the concept exploration test bed and summer 2001 operational experience, and the near term plans for the CIWS concept exploration.
Summary
The FAA Operational Evolution Plan (OEP) identified en route severe weather as one of the four problems that must be addressed if the US. air transportation system is to alleviate the growing gap between the demand for air transportation and the ability of the system to meet that demand. Convective...
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The 2001 demonstration of automated cloud forecast guidance products for San Francisco International Airport
May 13, 2002
Conference Paper
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10th Conf. on Aviation, Range, and Aerospace Meteorology (13th Conf. on Applied Climatology), 13-16 May 2002, pp. J99-J102.
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A system for providing cloud prediction guidance to aviation weather forecasters was demonstrated during the summer of 2001. The system was sponsored by the FAA, and developed by MIT Lincoln Laboratory in collaboration with SJSU, the University of Quebec at Montreal, Penn State University, and the Central Weather Service Unit (CWSU) at Oakland Center. Products were provided to forecasters at the CWSU, the NWS in Monterey, and the Weather Center at United Airlines. Real-time data are processed to support a display of weather graphics, and to provide input to a suite of four independent cloud forecast models developed specifically for the marine stratus application. The forecast models were run hourly each morning to provide updated forecasts during the evolution of cloud dissipation int he Bay area. As part of each update cycle, the four model forecasts were combined to provide a Consensus Forecast product. Weather observations and forecasts were provided to users on a web browser display.
Summary
A system for providing cloud prediction guidance to aviation weather forecasters was demonstrated during the summer of 2001. The system was sponsored by the FAA, and developed by MIT Lincoln Laboratory in collaboration with SJSU, the University of Quebec at Montreal, Penn State University, and the Central Weather Service Unit...
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Using ORPG to enhance NEXRAD products to support FAA critical systems
May 13, 2002
Conference Paper
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10th Conf. on Aviation, Range, and Aerospace Meteorology, 13-16 May 2002, pp. 77-80.
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The initial release of a new operational open architecture is currently being phased into the national WSR-88D (NEXRAD) radar network. This new Common Operations and Development Environment (CODE) includes the Open Radar Product Generator (ORPG) that replaces the existing NEXRAD Radar Product Generator. The new ORPG includes all the algorithms of the RPG it replaces. Future algorithms designed for use within NEXRAD also will be processed by the ORPG. CODE can also be used in a research capacity to significantly enhance the process of ORPG meteorological algorithm development. When used independently of a NEXRAD installation, CODE/ORPG provides multiple playback options for accessing real-time base data streams. This allows development and testing of new algorithms under the same environment an algorithm would encounter in an operational setting. This establishes a flow relationship from algorithm development through operational implementation within the common environment of CODE/ORPG. A six-month Build cycle for future CODE/ORPG releases has been established. An algorithm developed in a research CODE/ORPG capacity has an opportunity, at six-month intervals, to garner agency approval and undergo final preparation for operational release. The NEXRAD Radar Operations Center (ROC) needs about eight months preparation time from algorithm submission until release of the next CODE/ORPG version. For instance. Build 2 is to be released September 30. 2002. Algorithms for Build 2 inclusion had to be submitted by January 31, 2002. It will take about three months after the release for the entire NEXRAD network to be updated. The deadline for Build 3 submission is in July 2002 with a release date set in March 2003. Multiple Federal Aviation Administration (FAA) critical systems rely on products from NEXRAD algorithms. These projects include ITWS (Integrated Airport Weather System), WARP (Weather and Radar Processing), and ClWS (Corridor Integrated Weather System). Some of the NEXRAD products used include severe storm information, composite reflectivity factor depictions, and velocity data. In this paper, we discuss new algorithms and modifications to existing algorithms earmarked for the first few releases of the CODE/ORPG that produce products of importance to these FAA systems. They include modifications to the existing Anomalous Propagation Edited Composite Reflectivity algorithm released during Build 1 upgrades, a new high resolution, digital VIL (Vertically Integrated Liquid) algorithm slated for Build 2, and a Data Quality Assurance algorithm anticipated for Build 3.
Summary
The initial release of a new operational open architecture is currently being phased into the national WSR-88D (NEXRAD) radar network. This new Common Operations and Development Environment (CODE) includes the Open Radar Product Generator (ORPG) that replaces the existing NEXRAD Radar Product Generator. The new ORPG includes all the algorithms...
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