Publications
Improving RUC-1 wind estimates by incorporating near-real-time aircraft reports
August 1, 2000
Journal Article
Published in:
Weather For., Vol. 15, No. 4, August 2000, pp. 447-460.
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Summary
A verification study of wind accuracy is presented for wind nowcasts generated by augmenting Rapid Update Cycle (RUC) wind forecasts with near-real-time aircraft reports using the Integrated Terminal Weather System (ITWS) gridded winds algorithm. Aircraft wind reports collected between the end of the RUC data collection interval and the time each RUC forecasts is valid are available for use in augmenting the RUC wind forecast to form a wind nowcast. The 60-km resolution, hourly RUC-1 wind forecasts are used. ITWS-based nowcast wind errors and RUC forecast wind errors are examined statistically over a 1-yr dataset. The addition of the recent aircraft reports significantly reduces the rms vector error and the 90th percentile vector error. Also reduced is the number of hours of sustained large errors and the correlation among errors. The errors increase with increasing wind speed, in part due to an underestimation of wind speed that increases with increasing wind speed. The errors in the augmented wind fields decrease with increasing numbers of Aircraft Communications Addressing and Reporting System reports. Different types of weather are also seen to influence wind field accuracy.
Summary
A verification study of wind accuracy is presented for wind nowcasts generated by augmenting Rapid Update Cycle (RUC) wind forecasts with near-real-time aircraft reports using the Integrated Terminal Weather System (ITWS) gridded winds algorithm. Aircraft wind reports collected between the end of the RUC data collection interval and the time...
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Weather radar development and application programs
June 1, 2000
Journal Article
Published in:
Lincoln Laboratory Journal, Vol. 12, No. 2, 2000, pp. 367-382.
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Weather phenomena such as microburst wind shear and severe thunderstorms are major concerns to the aviation industry. A number of significant airplane accidents have resulted from wind-shear encounters during takeoff and landing, and thunderstorms are a major contributor to airplane delay. Providing fully automated and timely warnings of these phenomena by radar is challenging because it requires rapid and accurate analysis of the three-dimensional storm structure in the presence of intense ground-clutter returns. For the last two decades, Lincoln Laboratory has been tackling this challenge by applying advanced radar signal- and image-processing techniques to weather radar data. The resulting technology is being deployed in radar-based weather information systems at major airports throughout the United States. We first discuss the salient meteorological factors that contribute to the formation of microburst wind shear, then we provide some general background on the use of pulse-Doppler radar for weather detection. We describe two specific Lincoln Laboratory programs that have generated deployed systems: the Terminal Doppler Weather Radar (TDWR) and the ASR-9 Weather Systems Processor (WSP). The article concludes with a discussion of future detection strategies that emphasizes the fusion of weather radar data by the Integrated Terminal Weather System (ITWS).
Summary
Weather phenomena such as microburst wind shear and severe thunderstorms are major concerns to the aviation industry. A number of significant airplane accidents have resulted from wind-shear encounters during takeoff and landing, and thunderstorms are a major contributor to airplane delay. Providing fully automated and timely warnings of these phenomena...
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The design and validation of the ITWS synthetic sensor data generator
April 12, 2000
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-289
Summary
The Integrated Terminal Weather System (ITWS) is an aviation safety and air traffic management decision support system that acquires data from various FAA and NWS sensors and generates a number of products for dissemination to FAA facilities managing air traffic in the terminal area. The development and demonstrations of ITWS have been conducted over a multi-year period at several major airports (Memphis, TN, Orlando, FL, Dallas, TX, and New York, NY). Although there are many meteorological events observed at these four airports, the experimental test data sets obtained will not fully suffice for ITWS qualification testing because of limitations in the severity of the weather events and because of the sensor configurations available at these locations. This report describes the design and validation of the Synthetic Data Generator (SDG), which is a tool to provide a production ITWS system with meteorologically consistent scenarios and full ITWS sensor configurations that will create maximal computational loads that can be expected when the system is deployed. Also, the SDG will be a tool for ongoing ITWS maintenance and support. As such, the SDG will complement the extensive experimental data sets collected at the four ITWS demonstration sites. The SDG is designed to specify parameters for a collection of meteorological models describing the various weather phenomena, their motion, appearance, and growth/decay. The software creates several three-dimensional (3D) grids of reflectivity and velocity at each time-step. Finally, the SDG generates sensor (i.e., TDWR, NEXRAD, ASR-9) data by applying the model for each specific sensor's measurements to the 3D grids. The validation of the meteorological model and the sensor model data have been accomplished using a display tool and by assessing results numerically.
Summary
The Integrated Terminal Weather System (ITWS) is an aviation safety and air traffic management decision support system that acquires data from various FAA and NWS sensors and generates a number of products for dissemination to FAA facilities managing air traffic in the terminal area. The development and demonstrations of ITWS...
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Weather sensing and data fusion to improve safety and reduce delays at major west coast airports
November 30, 1999
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-290
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The objective of this study was to analyze the weather sensing and data fusion required to improve safety and reduce delays at a number of west coast airports that are not currently scheduled to receive an Integrated Terminal Weather System (ITWS). This report considers the Los Angeles (LAX), San Francisco (SFO), Seattle (SEA) and Portland, OR (PDX) international airports. A number of visits were made to the various ATC facilities to better understand their weather decision support operational needs. Analyses were made of an incident of lightning strikes to two aircraft at SEA in February 1999, and a prototype terminal winds product was developed for LAX that uses profilers as well as plane reports to update the the National Weather Service (NWS) Rapid Update Cycle (RUC) winds estimates. We found that an augmented ITWS could potentially address safety concerns for triggered lightning strikes and vertical wind shear in winter storms at Portland and Seattle. An augmented ITWS terminal winds product (that uses wind profiler data in addition to the current ITWS sensors) could provide very large delay reductions for LAX and SFO during winter storms as a component of a wake vortex advisory system. This augmented product also could provide significant delay reduction benefits at SEA. The sensors required to obtain the projected benefits at SFO do not exist currently. Portland may warrant additional sensors to address the vertical wind shear problems, and LAX would require additional sensors for a wake vortex advisory system. We recommend near-term experimental measurements at PDX to determine the optimum sensor mix and that an operational evaluation of the prototype augmented ITWS terminal winds product be carried out at LAX to determine if the current sensor mix can meet operational needs. Lightning strike data at SEA and PDX should be analyzed to determine if a proposed triggered lightning predictant is accurate.
Summary
The objective of this study was to analyze the weather sensing and data fusion required to improve safety and reduce delays at a number of west coast airports that are not currently scheduled to receive an Integrated Terminal Weather System (ITWS). This report considers the Los Angeles (LAX), San Francisco...
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An evaluation of the ASR-9 weather channel based on observations from the ITWS prototypes
September 23, 1999
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-270
Summary
The Federal Aviation Administration's (FAA) Airport Surveillance Radar (ASR-9) is a high-scan-rate system which provides a "critical" function in terms of air traffic control (ATC). In addition to its primary role of air traffic surveillance, the system also generates precipitation data for display on air traffic specialists' radar scopes and for use by automated systems such as the Integrated Terminal Weather System (ITWS) and Weather Systems Processor (WSP). Air traffic managers use these data to provide optimum routes for aircraft operating in and near the Terminal Radar Approach Control (TRACON) airspace. The primary advantage of the ASR-9 - as an aviation weather radar - over either the Terminal Doppler Weather Radar (TDWR) or the Next Generation Weather Radar (NEXRAD) is the rapid update rate, i.e., 30 seconds, which provides air traffic managers with a more accurate representation of weather echo location within the sensor's domain. This is far superior toeither the TDWR or NEXRAD, which takes from 2.5 to 6 minutes to create a volume scan, depending on the scan strategy. The sensor is also quite reliable, with limited down time. An analysis of ASR-9 data from the ITWS prototypes has uncovered a number of problems, which impact the quality of the precipitation data. The data quality issues discussed are overly aggressive ground clutter suppression, polarization mode issues, hardware failures associated with high beandlow beam switching, attenuatiodsignal depolarization, beam-filling losses, bright- band contamination, distant weather contamination, calibration issues, and radadantenna failures. The recommendations to address the ASR-9 data quality issues can be grouped into three categories: "Variable Site Parameter (VSP)" adjustments, hardware component maintenance checks, and automated flagging of data quality problems. The report includes discussion of the frequency and characteristics of each degradation, presenting both hardware and non- hardware related problems, and concludes with proposed solutions to the problems and recommendations designed to improve the overall utility of the ASR-9 precipitation data.
Summary
The Federal Aviation Administration's (FAA) Airport Surveillance Radar (ASR-9) is a high-scan-rate system which provides a "critical" function in terms of air traffic control (ATC). In addition to its primary role of air traffic surveillance, the system also generates precipitation data for display on air traffic specialists' radar scopes and...
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Wind shear detection using the Next Generation Airport Surveillance Radar
July 12, 1999
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-266
Summary
The Federal Aviation Administration (FAA) is deploying a Weather Systems Processor (WSP) for the current-generation Airport Surveillance Radar - ASR-9. This modification exploits the coherency of the ASR-9 to perform Doppler wind measurement. Signature recognition algorithms then automatically detect low altitude wind shear phenomena, track thunderstorm motion and display appropriate graphical and alphanumeric alerts to air traffic control (ATC) personnel. The FAA and U.S. Air Force are now procuring an ASR-11 to replace older terminal surveillance radars at facilities that did not receive the ASR-9. Although the antenna pattern, scan rate and energy-on-target of the ASR-11 match the corresponding parameters of the ASR-9, two other characteristics are markedly different. It utilizes a low peak power solid state transmitter that requires transmission of long, coded waveforms and a pulse compression receiver. Secondly, its pulse transmission sequence consists of short (five-pulse) bursts at both different pulse-repetition frequencies (PRF) and different RF frequencies. In this report, we assess the technical and operational issues associated with adding a WSP to the ASR-11. The existing WSP data processing and display technology are largely re-usable for the ASR-11 based WSP. Ground clutter filter coefficients and the length and number of coherent processing intervals would need to be changed to conform to the ASR-11 pulse transmission strategy, and straightforward adaptations to the equations used in the pulse-pair weather reflectivity and Doppler velocity estimation would be required. With these changes, the ASR-11 could host the WSP, subject to performance degradations for low reflectivity wind shear phenomena such as dry microbursts and gust fronts. A benefits assessment waas performed to evaluate the operational requirements for an ASR-11 based WSP. Given that the FAA has already committed to deploy improved Low Level Wind Shear Alert Systems (LLWAS) at most ASR-11 airports, the incremental safety benefits for the ASR-11 WSP appear to be less than the cost of the equipment. A case can be made for deployment based on "situational awareness" benefits that the WSP has been demonstrated to provide to air traffic controllers. We estimate that the value to the public and airline industry of reductions in aircraft delay, and avoidance of unnecessary diversions, would be in excess of eight million dollars per year tallied across 18 of the larger ASR-11 equipped airports.
Summary
The Federal Aviation Administration (FAA) is deploying a Weather Systems Processor (WSP) for the current-generation Airport Surveillance Radar - ASR-9. This modification exploits the coherency of the ASR-9 to perform Doppler wind measurement. Signature recognition algorithms then automatically detect low altitude wind shear phenomena, track thunderstorm motion and display appropriate...
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The FAA Terminal Convective Weather Forecast product: scale separation filter optimization
July 12, 1999
Conference Paper
Published in:
29th Int. Conf. on Radar Meteorology, 12-16 July 1999.
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A large percentage of serious air traffic delay at major airports in the warm season is caused by convective weather. The FAA Convective Weather Product Development team (PDT) has developed a Terminal Convective Weather Forecast product (TCWF) that can account for short-term (out to 60 min) systematic growth and decay of thunderstorms. The team began work three years ago by evaluating air traffic user needs and requirements. We found that users were willing to trade off forecast accuracy for longer lead times, especially for air traffic management plans that were easy to implement or that incurred low risk (Forman, et al., 1999). The PDT was able to develop an operationally useful forecast product that has been demonstrated in Dallas, TX since March, 1998 (Hallowell, et al., 1999). Further improvements have been made, and testing is now taking place at both Dallas and Orlando, FL. This paper summarizes the basic algorithm methodology and presents quantitative results on optimization of the scale separation filter, which is an integral aspect of the forecast algorithm.
Summary
A large percentage of serious air traffic delay at major airports in the warm season is caused by convective weather. The FAA Convective Weather Product Development team (PDT) has developed a Terminal Convective Weather Forecast product (TCWF) that can account for short-term (out to 60 min) systematic growth and decay...
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Review of NYC ITWS during the September 7, 1998 severe weather event
May 26, 1999
Project Report
Published in:
Project Report ATC-269, MIT Lincoln Laboratory
Summary
The New York City Integrated Terminal Weather System (ITWS) prototype became operational for the first time on August 30, 1998. Although this was near the end of the region's convective season, site staff were afforded a unique chance to assess the system's performance during Labor Day weekend on the afternoon of September 7 when a line of severe thunderstorms wreaked havoc over large areas of the Tri-state region. The storm with gusts reported as high as 80 mph, caused fatalities as boats overturned and trees fell on cars. Tornadoes were confirmed over New Jersey and Long Island, with major structural damage occurring in other areas as the result of strong straight-line winds and hail reported as large as 1.75 inches in diameter. Significant airport delays were experienced at the three major New York airports (over 600 flights delayed at least 15 minutes) and several hundred flights were cancelled. This report will assess the performance of ITWS and NEXRAD products during the time severe weather impacted the TRACON area, from about 1700 to 1930 UTC on September 7 (hereafter all times will be given in UTC). It will also discuss the synoptic weather setting and conclude with a section on the operational benefits users derived from ITWS on this day.
Summary
The New York City Integrated Terminal Weather System (ITWS) prototype became operational for the first time on August 30, 1998. Although this was near the end of the region's convective season, site staff were afforded a unique chance to assess the system's performance during Labor Day weekend on the afternoon...
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Achieving higher integrity in NEXRAD products through multi-sensor integration
January 10, 1999
Conference Paper
Published in:
8th Conf. on Aviation, Range, and Aerospace Meteorology (ARAM), 10-15 January 1999.
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Summary
The initial operational concept for the NEXRAD focused on support for the operational forecaster based on longstanding practice in use of weather radars by the National Weather Service (NWS) and Air Force as well as difficulties in developing reliable, fully automated phenomena detection algorithms [Crum, 1998]. By contrast, achieving high integrity in the narrow band products provided by NEXRAD to external users has received much less attention in the NEXRAD product development process thus far. However, other government weather information systems [especially the FAA's Integrated Terminal Weather System (ITWS) and the Weather and Radar Processor (WARP)] and non-meteorologist external users of the NEXRAD products through the NEXRAD Information Distribution System (NIDS) vendors need very high integrity NEXRAD products. In the NWS context, the direct utilization of NEXRAD products into numerical weather prediction models will also create much more stringent requirements for integrity of the NEXRAD base data. Achieving very high integrity through automated analysis of only the data from a single NEXRAD is very difficult. In this paper, we consider the use of a much wider range of contextual information to create high integrity external user products. For instance, with the NEXRAD Open RPG and connectivity to AWIPS and ITWS, a system architecture will exist that will facilitate the implementation of NEXRAD product quality control algorithms that utilize information from other sensors. In the following sections, we present some examples of how information from various other sources might be used to improve the quality of the data from a NEXRAD. We first show an example of how data from adjacent NEXRADs can be used to help edit out the anomalous propagation (AP) ground clutter which currently is corrupting a number of the NEXRAD reflectivity products intended for air traffic controller use. In cases where the NEXRAD is near a major metropolitan area, data from the FAA's TDWR can be used to improve the integrity of the NEXRAD reflectivity products used for hydrology. Similarly, gridded wind fields estimated from multiple Doppler analyses, aircraft reports, and numerical models can be used to help address difficult challenges in Doppler ambiguity resolution for a single NEXRAD radar. The paper concludes with suggestions for near term demonstration and evaluation of multi sensor approaches to achieving high integrity in the NEXRAD products.
Summary
The initial operational concept for the NEXRAD focused on support for the operational forecaster based on longstanding practice in use of weather radars by the National Weather Service (NWS) and Air Force as well as difficulties in developing reliable, fully automated phenomena detection algorithms [Crum, 1998]. By contrast, achieving high...
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The Terminal Convective Weather Forecast demonstration at the DFW International Airport
January 10, 1999
Conference Paper
Published in:
8th Conf. on Aviation, Range, and Aerospace Meteorology (ARAM), 10-15 January 1999.
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The FAA Convective Weather Product Development Team (PDT) is tasked with developing products for convective weather forecasts for aviation users. The overall product development is a collaborative effort between scientists from MIT Lincoln Laboratory (MIT/LL), the National Center for Atmospheric Research (NCAR), and the National Severe Storms Laboratory (NSSL). As part of the PDT, MIT/LL is being funded to develop algorithms for accurately forecasting the location of strong precipitation in and around airport terminal areas. We began by consulting with air traffic personnel and commercial airline dispatchers to determine the needs of aviation users. Users indicated that convective weather, particularly line storms, caused the most consistent problems for managing air traffic. These storms are by far the major cause of aircraft delays and diversions. MIT/LL has already developed the Integrated Terminal Weather System (ITWS) which combines a variety of near-airport sensors to provide a wide range of current weather information to aviation users. Raytheon is currently building the production ITWS system which will be deployed at 45 major airports by 2003. The initial capability ITWS already provides some convective weather predictive capabilities in the form of storm motion vectors and "Storm Extrapolated Positions" (SEP; leading edge of storm at 10 and 20 minutes). But ITWS users indicated a desire for enhanced forecasts which showed the full spatial extent of the weather, how the weather would change (grow or decay) and extended forecast time periods to at least out one hour. Our approach is to develop an algorithm which may be added as a future product improvement to the ITWS system. Previous attempts at producing forecasts have focused on convective initiation and building from short-term (20-30 min) cell forecasts. Our "reverse time" approach of attacking longer time scale (60 min) features first is an outgrowth of addressing user needs and the discovery of improved tracking techniques for large scale precipitation features. The "Growth and Decay Tracker" developed by MIT/LL (Wolfson et.al., 1999) allows us to generate accurate short and long term forecasts of large scale precipitation features. This paper details the Terminal Convective Weather Forecast (TCWF) demonstration ongoing at Dallas/Ft. Worth International Airport (DFW) and discusses the underlying algorithm being developed.
Summary
The FAA Convective Weather Product Development Team (PDT) is tasked with developing products for convective weather forecasts for aviation users. The overall product development is a collaborative effort between scientists from MIT Lincoln Laboratory (MIT/LL), the National Center for Atmospheric Research (NCAR), and the National Severe Storms Laboratory (NSSL). As...
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