Publications
Enhancement to Terminal Doppler Weather Radar to improve aviation weather services
May 13, 2002
Conference Paper
Published in:
10th Conf. on Aviation, Range, and Aerospace Meteorology, 13-16 May 2002, pp. 28-31.
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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 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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En route weather depiction benefits of the NEXRAD vertically integrated liquid water product utilized by the Corridor Integrated Weather System
May 13, 2002
Conference Paper
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10th Conf. on Aviation, Range, and Aerospace Meteorology, 13-16 May 2002, pp. 120-123.
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It is demonstrated in this paper that weather depictions in an operational environment based upon VIL provide more meaningful information for en route traffic routing than a BREF product. VIL precipitation proves advantageous in limiting contamination from Anomalous Propagation (AP) ground clutter, biological targets (e.g., birds and insects), and radar artifacts. The extended vertical coverage of VIL sampling also better depicts storm cells as they first develop, further assisting traffic managers achieve more efficient use of tactical airspace when weather occurs unexpectedly.
Summary
It is demonstrated in this paper that weather depictions in an operational environment based upon VIL provide more meaningful information for en route traffic routing than a BREF product. VIL precipitation proves advantageous in limiting contamination from Anomalous Propagation (AP) ground clutter, biological targets (e.g., birds and insects), and radar...
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Low altitude boyancy wave turbulence - a potential aviation safety threat
May 13, 2002
Conference Paper
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10th Conf. on Aviation, Range, and Aerospace Meteorology, 13-16 May 2002, pp. 375-378.
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Summary
Weather comprises one of the most significant safety hazards facing civilian aviation today. This hazard has been significantly reduced by the development and use of microburst wind shear detection technologies such as the Low Level Wind Shear Alert System (LLWAS), the Terminal Doppler Weather Radar (TDWR), the ASR-9 Weather Systems Processor (WSP) and the Integrated Terminal Weather System (ITWS). Each was designed to detect and warn for the presence of low altitude wind shear resulting from microburst and gust fronts. These systems have made an unquestionable improvement in aviation safety; however, there are other forms of low altitude wind shear hazardous to aviation. This paper provides a description of a low altitude buoyancy wave (BW) induced turbulence phenomena that appears to also be a significant hazard to aviation. Buoyancy wave turbulence can be particularly dangerous since it often occurs outside regions containing intense precipitation where pilots typically expect to encounter thunderstorm induced wind shear conditions. Section 2 of this paper contains a general description of BW phenomena based on laboratory and observational studies. Section 3 will briefly summarize several incidents where commercial and civilian aircraft have encountered buoyancy waved induced turbulence. A summary and conclusions are made in section 4.
Summary
Weather comprises one of the most significant safety hazards facing civilian aviation today. This hazard has been significantly reduced by the development and use of microburst wind shear detection technologies such as the Low Level Wind Shear Alert System (LLWAS), the Terminal Doppler Weather Radar (TDWR), the ASR-9 Weather Systems...
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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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COTS fusion tracker evaluation
February 15, 2002
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-302
Summary
Lincoln Laboratory was tasked by the FAA to measure the performance of a representative sample of current commercial off-the-shelf (COTS) fusion trackers. This effort included cataloging the companies that have available ATC fusion trackers, acquiring executable tracker images from as many as possible of these trackers, running the commercial tracker code on the test sets, and evaluating the performance achieved. This report presents an overall review of the state-of-the-art of fusion tracker as applied to the FAA surveillance problem. Average statistics of performance, as well as performance in special situations, are included. In each case, the performance of fusion is compared against the performance of single sensor and mosaic tracking. Thus, the advantages and disadvantages of fusion will be evident. The statistics may also permit the generation of a fusion tracker specification should the FAA decide to procure one as part of a future automation system.
Summary
Lincoln Laboratory was tasked by the FAA to measure the performance of a representative sample of current commercial off-the-shelf (COTS) fusion trackers. This effort included cataloging the companies that have available ATC fusion trackers, acquiring executable tracker images from as many as possible of these trackers, running the commercial tracker...
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New products for the NEXRAD ORPG to support FAA critical systems
February 9, 2002
Conference Paper
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19th Int. Conf. on Interactive Processing Systems for Meteorology, Oceanography and Hydrology, 9-13 February 2002.
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A number of Federal Aviation Administration (FAA) critical systems rely on products from the NEXRAD (WSR-88D) suite of algorithms. These systems include MIAWS (Medium Intensity Airport Weather System), ITWS (Integrated Terminal Weather System), CIWS (Corridor Integrated Weather System), and WARP (Weather and Radar Processing). With the advent of the NEXRAD Open Radar Product Generator (ORPG), a six-month build cycle has been established for the incorporation of new or improved algorithms. This build cycle provides the mechanism for the integration of new products into the algorithm suite tailored to the needs of these FAA systems now and into the future. Figure 1 is useful for visualizing the MIT/LL ORPGnet. Four of the ORPGnet systems are located at MIT/LL headquartered in Lexington, MA. These four systems form the core of the development center where algorithms are developed for and implemented into the ORPG environment. Part of the development process includes examination of algorithm products created from past weather. A number of utilities are available for playback of various versions of NEXRAD Archive II base data: from tape or disk files in standard or LDM formats. Additionally, MIT/LL operates the CIWS demonstation project for the FAA. The ORPG clones at the development center have access to base data from 26 NEXRAD radars from the Midwest to the East Coast of the United States ingested for CIWS. The FAA has tasked the Massachusetts Institute of Technology's Lincoln Laboratory (MIT/LL) with developing algorithms for the ORPG to address their systems' needs. Many of these algorithms will also prove useful to other users of NEXRAD products such as the National Weather Service and the Department of Defense. MIT/LL has created a network of ten ORPGs, or an ORPGnet, to use for the purpose of developing, testing, and implementing new algorithms targeted to specific builds. The benefits of the ORPGnet will be discussed in more detail later in this paper. MIT/LL has provided improvements to existing algorithms or developed new algorithms for the first three build cycles of the ORPG (Istok et al., 2002; Smalley and Bennett, 2002). Development of more algorithms is currently in progress for upcoming build cycles. In addition to describing ORPGnet, this paper will focus on its use in the development of a new Data Quality Assurance (DQA) algorithm, an improved High Resolution VIL (HRVIL) algorithm, and progress on the development of the enhanced Echo Tops (EET) algorithm; as well as the symbiotic relationship of these algorithms to the FAA critical systems.
Summary
A number of Federal Aviation Administration (FAA) critical systems rely on products from the NEXRAD (WSR-88D) suite of algorithms. These systems include MIAWS (Medium Intensity Airport Weather System), ITWS (Integrated Terminal Weather System), CIWS (Corridor Integrated Weather System), and WARP (Weather and Radar Processing). With the advent of the NEXRAD...
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