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SFO marine stratus forecast system documentation

Summary

San Francisco International Airport (SFO) experiences frequent low ceiling conditions during the summer season due to marine stratus clouds. Stratus in the approach zone prevents dual approaches to the airport??s closely spaced parallel runways, effectively reducing arrival capacity by half. The stratus typically behaves on a daily cycle, with dissipation occurring during the hours following sunrise. Often the low ceiling conditions persist throughout the morning hours and interfere with the high rate of air traffic scheduled into SFO from mid-morning to early afternoon. Air traffic managers require accurate forecasts of clearing time to efficiently administer Ground Delay Programs (GDPs) to match the rate of arriving aircraft with expected capacity. The San Francisco Marine Stratus Forecast System was developed as a tool for anticipating the time of stratus clearing. The system relies on field-deployed sensors as well as routinely available regional surface observations and satellite data from the Geostationary Operational Environmental Satellite (GOES-West). Data are collected, processed, and input to a suite of forecast models to predict the time that the approach zone will be sufficiently clear to perform dual approaches. Data observations and model forecasts are delivered to users on an interactive display accessible via the Internet. The system prototype was developed under the sponsorship of the FAA Aviation Weather Research Program (AWRP). MIT Lincoln Laboratory served as technical lead for the project, in collaboration with San Jose State University, the University of Quebec at Montreal, and the Center Weather Service Unit (CWSU) at the Oakland Air Route Traffic Control Center (ARTCC). The National Weather Service (NWS), under the direction of the NWS Forecast Office in Monterey, assumed responsibility for operation and maintenance of the system following technical transfer in 2004. This document was compiled as a resource to support continuing system operation and maintenance.
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Summary

San Francisco International Airport (SFO) experiences frequent low ceiling conditions during the summer season due to marine stratus clouds. Stratus in the approach zone prevents dual approaches to the airport??s closely spaced parallel runways, effectively reducing arrival capacity by half. The stratus typically behaves on a daily cycle, with dissipation...

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Advanced aviation weather forecasts

Published in:
Lincoln Laboratory Journal, Vol. 16, No. 1, June 2006, pp. 31-58.

Summary

The U.S. air transportation system faces a continuously growing gap between the demand for air transportation and the capacity to meet that demand. Two key obstacles to bridging this gap are traffic delays due to en route severe-weather conditions and airport weather conditions. Lincoln Laboratory has been addressing these traffic delays and related safety problems under the Federal Aviation Administration's (FAA) Aviation Weather Research Program. Our research efforts involve real-time prototype forecast systems that provide immediate benefits to the FAA by allowing traffic managers to safely reduce delay. The prototypes also show the way toward bringing innovative applied meteorological research to future FAA operational capabilities. This article describes the recent major accomplishments of the Convective Weather and the Terminal Ceiling and Visibility Product Development Teams, both of which are led by scientists at Lincoln Laboratory.
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Summary

The U.S. air transportation system faces a continuously growing gap between the demand for air transportation and the capacity to meet that demand. Two key obstacles to bridging this gap are traffic delays due to en route severe-weather conditions and airport weather conditions. Lincoln Laboratory has been addressing these traffic...

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Upgrade and technology transfer of the San Francisco Marine Stratus Forecast system to the National Weather Service

Published in:
86th AMS Annual Mtg., 1st Symp. on Policy Research, January 2006.

Summary

The local airspace surrounding the San Francisco International Airport (SFO) is prone to regular occurrences of low ceiling conditions from May through October due to the intrusion of marine stratus along the Pacific coast. The low cloud conditions prohibit dual parallel landings of aircraft to the airport's closely spaced parallel runways, thus effectively reducing the arrival capacity by a factor of two. The behavior of marine stratus evolves on a daily cycle, filling the San Francisco Bay region overnight, and dissipating during the morning. Often the low ceiling conditions persist throughout the morning hours and interfere with the high rate of air traffic scheduled into SFO from mid-morning to early afternoon. The result is a substantial number of delayed flights into the airport and a negative impact on the National Air Space (NAS). Air traffic managers face a continual challenge of anticipating available operating capacity so that the demand of incoming planes can be metered to match the availability of arrival slots.
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Summary

The local airspace surrounding the San Francisco International Airport (SFO) is prone to regular occurrences of low ceiling conditions from May through October due to the intrusion of marine stratus along the Pacific coast. The low cloud conditions prohibit dual parallel landings of aircraft to the airport's closely spaced parallel...

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A characterization of NWP ceiling and visibility forecasts for the terminal airspace

Published in:
86th AMS Annual Meeting, 1st Symp. on Policy Research, 2006.

Summary

The Federal Aviation Administration (FAA) is sponsoring a Terminal Ceiling and Visibility (C&V) initiative to provide automated C&V guidance to the air traffic managers for both tactical (0-2 hour) and strategic (3-12 hour) decision making. To meet these requirements, particularly in the strategic time frame, it will most likely be necessary for the C&V system to incorporate guidance from an explicit numerical weather prediction (NWP) model. If NWP forecasts are found to be suitable for this application, they will be used as the backbone of the terminal C&V forecast system. More details on the terminal area C&V forecast product development for the FAA can be found in Allan et al. (2004). Before these NWP forecast products can be used, it is necessary to first characterize their accuracy relative to operational air traffic control (ATC) requirements. This makes it possible to exploit observed strengths, avoid weaknesses, and facilitate a better utilization of NWP forecast products. This study provides an assessment tailored specifically to address the terminal C&V application. Consequently, the results represent forecast performance for relatively small geographic locations that for practical purposes can be considered point forecasts. It is our intention to answer four questions with this preliminary analysis: 1. How accurate are the NWP forecasts relative to the observational truth and a human generated forecast? 2. For the terminals of interest to this study (i.e. New York City Airports), are there any advantages to utilizing a non-hydrostatic mesoscale model run at horizontal resolutions of 3 km or less? 3. Do the NWP models exhibit forecast skill for non-traditional forecast metrics such as trends in C&V parameters and timings of threshold crossings associated with the onset and clearing of low ceiling and visibility conditions? 4. Are there obvious situations/conditions during which the NWP forecasts have more/less skill? In addition to a report on the NWP terminal ceiling and visibility forecast accuracy, we provide preliminary recommendations on the direction we feel this line of research should pursue, and where we see opportunities to utilize NWP forecasts in an automated terminal C&V decision guidance system. An ancillary goal of this study is to assemble the analysis software infrastructure required to quantitatively evaluate numerical forecast accuracy. We envision using these tools to develop and test modifications to the translation algorithms and techniques that will be necessary to integrate the NWP forecasts into the C&V guidance system. They will be instrumental in reducing the time required to make engineering turns during the upcoming development and implementation stages of this research.
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Summary

The Federal Aviation Administration (FAA) is sponsoring a Terminal Ceiling and Visibility (C&V) initiative to provide automated C&V guidance to the air traffic managers for both tactical (0-2 hour) and strategic (3-12 hour) decision making. To meet these requirements, particularly in the strategic time frame, it will most likely be...

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Terminal ceiling & visibility product development for northeast airports

Author:
Published in:
86th AMS Annual Meeting, 1st Symp. on Policy Research, 27 January - 3 February 2006.

Summary

Within the FAA Aviation Weather Research Program (AWRP), the Terminal Ceiling and Visibility Product Development Team (TC&V PDT) is responsible for development of forecast guidance products to mitigate the loss of terminal operating capacity associated with low ceiling and visibility restrictions. In particular, accurate anticipation of the onset and cessation of Instrument Meteorological Conditions (IMC) allows the opportunity for air traffic managers to effectively regulate traffic to utilize available capacity. The TC&V PDT approach is to develop forecast guidance solutions that are specific to individual high volume terminals that experience substantial loss of capacity. Due to the inter-hub dependencies of traffic flow, efficiency gains at individual key airports translate to a general reduction of total aircraft delay through the entire National Airspace System. The first key airport targeted was San Francisco International Airport (SFO). A system was developed to provide forecast guidance of the clearing time of stratus cloud that frequently restricts approach capacity during the summer months (Clark, 2002). This prototype system was transferred to the National Weather Service in 2004 (Ivaldi et al., 2006) The current focus of the Terminal C&V PDT is on ceiling and visibility restrictions associated with synoptic-scale transient weather systems that regularly impact the Northeast U.S. during the winter months, typically from November through April. The runway configuration and instrumentation at many of the major northeast terminals (Boston, New York Laguardia and Kennedy, Newark, Philadelphia, etc.) are very susceptible to IMC weather, resulting in a dramatic reduction in operating capacity. The multitude of phenomena contributing to IMC (e.g. frontal cloud shields, advection and radiation fog, precipitation of varying intensity and type, etc.) poses a difficult forecasting challenge. The Terminal C&V PDT is pursuing a variety of candidate technologies that will be integrated to provide a comprehensive solution. Trials of these forecast technologies are being developed using the NYC airspace as an experimental domain for both weather and operations. Development is progressing on two fronts: 1) improvement in the delivery of existing C&V information, and 2) development of new forecast technologies. The ultimate objective is integration of forecasts with operational information to provide a complete decision guidance tool. This paper introduces an experimental display tool and distribution mechanism for delivering C&V data and forecasts, focused on the NYC airspace. Initially, this tool relies on routinely available weather observations and forecasts. The intent of providing such a tool early in the product development stage is to engage the operational community (forecasters, dispatchers, and traffic managers) in the assessment and selection of candidate forecast technologies that are most appropriate for supporting operational decision making. During development, these technologies will be inserted into the display framework to evaluate their effectiveness in real time trials. An overview of the technologies under consideration is provided.
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Summary

Within the FAA Aviation Weather Research Program (AWRP), the Terminal Ceiling and Visibility Product Development Team (TC&V PDT) is responsible for development of forecast guidance products to mitigate the loss of terminal operating capacity associated with low ceiling and visibility restrictions. In particular, accurate anticipation of the onset and cessation...

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Advanced terminal weather products demonstration in New York

Published in:
Proc. 11th Conf. on Aviation, Range and Aerospace Meteorology, 4-8 October 2004.

Summary

Weather continues to be a significant source of delay for aircraft destined to and departing from the New York metropolitan area, with weather delays through the first half of 2004 reaching levels not seen since 2000. In Allan et al. (2001), it was shown that total arrival delays on days with low ceiling and visibility at Newark Airport (EWR) averaged 210 hours, increasing to an average of 280 hours on days with thunderstorms impacting EWR operations. An analysis of Ground Delay Programs (GDPs) due to weather in the National Airspace System was performed for 2002-20031. Low ceilings, thunderstorms, snow, and wind were all shown to be significant sources of delay (Figure 1). These same weather conditions that lead to GDPs often also lead to holding and long departure delays. In 1998, demonstration of a prototype Integrated Terminal Weather System (ITWS) began in the New York area, helping significantly reduce terminal delays from convection, high surface winds, and vertical wind shear (Allan et al., 2001). In 2002, a new demonstration system, the Corridor Integrated Weather System (CIWS), was introduced at New York Center (ZNY) to help mitigate convective weather delays in the enroute airspace. Substantial benefits were realized from this system and are documented in Robinson et al. (2004). While systems such as ITWS and CIWS have helped significantly with convective weather, much has been learned during the field-testing of these systems about areas where existing research and technology could be leveraged to reduce weather delay in areas that have not been addressed previously. This paper will discuss four experimental products that recently have been or will be fielded in the NY area and how they are expected to benefit the aviation system. Enhancements to the Terminal Convective Weather Forecast (TCWF) address delays in convective weather, snowstorms, and steady rain. The newly fielded Route Availability Planning Tool (RAPT) addresses departure delays in convective weather. The Ceiling and Visibility (C&V) Diagnosis and Prediction Product will address delay due to low ceiling and visibility. The Path-Based Shear Detection (PSD) tool is expected to help both to reduce delays on days with high winds and to indicate regions of potential low altitude turbulence.
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Summary

Weather continues to be a significant source of delay for aircraft destined to and departing from the New York metropolitan area, with weather delays through the first half of 2004 reaching levels not seen since 2000. In Allan et al. (2001), it was shown that total arrival delays on days...

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The 2001 demonstration of automated cloud forecast guidance products for San Francisco International Airport

Author:
Published in:
10th Conf. on Aviation, Range, and Aerospace Meteorology (13th Conf. on Applied Climatology), 13-16 May 2002, pp. J99-J102.

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 (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.
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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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Forecast aids to lessen the impact of marine stratus on San Francisco International Airport

Author:
Published in:
Proc. Ninth Conf. on Aviation, Range, and Aerospace Meteorology, 11-15 September 2000, pp. 317-322.

Summary

San Francisco International Airport (SFO) is unable to use independent parallel approaches to its closely-spaced parallel runways when marine stratus is present in the approach. Delay programs are imposed to regulate the flow of traffic to match the true arrival capacity of the airport. Failure to forecast accurately the times of onset and dissipation of stratus in the approach results in unnecessary delays, costly airborne holding and diversions, or in wasted capacity as the traffic management planners fail to match the arrival rate to the actual airport capacity. Previous studies have shown that accurate 1-2 hour forecasts of the times of clearing in the approach could provide substantial reductions in the delays and inefficiencies associated with the marine stratus impacts on air traffic at SFO. The San Francisco Marine Stratus Initiative has provided a four-year focus on this problem and has resulted in the development of several forecast algorithms that will aid, the operational forecasting of the dissipation of marine stratus in the approach to SFO (Clark and Wilson, 1997). These algorithms involve new techniques for the analysis of observational data and statistical and dynamical prognosis of the behavior of the marine stratus. This discussion of the design and the performance of these algorithms provides an overview of the status of this project.
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Summary

San Francisco International Airport (SFO) is unable to use independent parallel approaches to its closely-spaced parallel runways when marine stratus is present in the approach. Delay programs are imposed to regulate the flow of traffic to match the true arrival capacity of the airport. Failure to forecast accurately the times...

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The Marine Stratus Initiative at San Francisco International Airport

Author:
Published in:
MIT Lincoln Laboratory Report ATC-252

Summary

San Francisco International Airport is one of the busiest airports in the United States and one of the highest delay airports in terms of total aircraft delay hours and number of imposed air traffic delay programs. As with most airports, weather is the primary cause of aircraft delay. In particular, the local airspace is prone to regular occurrences of low cloud ceiling conditions due to intrusion of marine air from the eastern Pacific Ocean from May through September. Typically, this layer of stratus clouds forms in the San Francisco Bay area overnight and dissipates during the middle to late morning. The timing of the stratus cloud dissipation is such that it frequently poses a threat to the morning arrival push of air traffic into San Francisco. Weather forecasters at the Central Weather Service Unit (CWSU) at the Oakland AirRoute Traffic Control Center are responsible for providing a forecast whether or not the cloudiness will impact morning traffic operations. This information is used for decision making by the Traffic Management Unit at Oakland Center in order to optimally match arriving traffic demand to available airport capacity. As part of the FAA's Integrated Terminal Weather System, the Weather Sensing Group at MIT Lincoln Laboratory has begun an effort entitled the "Marine Stratus Initiative." Its objective is to provide improved weather information and forecast guidance to the Oakland CWSU, which is responsible for providing weather forecasts to air traffic managers. During 1995, the main focus of the project was the design and implementation of a data acquisition, communication, and display infrastructure that provides forecasters with new sources of weather data and information. These initial capabilities were tested during an operational demonstration in August and September. As the project continues, the intent is to improve these new data sources and develop an automated or semi-automated algorithm that will process raw information to provide weather forecasters with numerical guidance to assist them in the forecast process. A description of airport operations at San Francisco and the impact of marine stratus are presented. An explanation is given of the marine stratus phenomenology and the primary factors contributing to cloud dissipation. This conceptual model of the dissipation process is used to define system requirements. A description of the hardware, communications, and display subsystems is provided. An overview of the 1995 demonstration, including user comments, is presented, as well as future plans for meeting the longer-term objectives of the project.
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Summary

San Francisco International Airport is one of the busiest airports in the United States and one of the highest delay airports in terms of total aircraft delay hours and number of imposed air traffic delay programs. As with most airports, weather is the primary cause of aircraft delay. In particular...

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An automated method for low level wind shear alert system (LLWAS) data quality analysis

Author:
Published in:
MIT Lincoln Laboratory Report ATC-207

Summary

The Low Level Windshear Alert System (LLWAS) is an anemometer-based surface network used for detection of hazardous wind shear and acquisition of operational wind information in the airport terminal area. The quality of wind data provided by the LLWAS anemometers is important for the proper performance of the LLWAS wind shear detection algorithms. This report describes the development of an automated method for anemometer data quality (DQA). This method identifies potential data quality problems through comparison of wind data from each sensor within a network to the mean wind speed and direction of the entire network. The design approach and implementation are described, and results from testing using data from the demonstration Phase III LLWAS network in Orlando, FL are reported. Potential improvements to the automated DQA algorithm are presented based on experience gained during analysis of the Orlando data. These recommended improvements are provided to assist future development and refinement of the DQA methodology to be performed by the FAA Technical Center.
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Summary

The Low Level Windshear Alert System (LLWAS) is an anemometer-based surface network used for detection of hazardous wind shear and acquisition of operational wind information in the airport terminal area. The quality of wind data provided by the LLWAS anemometers is important for the proper performance of the LLWAS wind...

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