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Ceiling and VisibilityMarine stratus is the trapped cool and humid air from sea breezes. In the San Francisco Bay area, marine stratus causes frequent low ceilings at San Francisco International Airport (SFO). During these events, the airport cannot use independent parallel approaches and it must impose delay programs to regulate arrivals. SFO has the highest number of imposed delay programs of airports in the United States. Marine stratus is also a problem at other major coastal airports.Failure to forecast accurately the times of onset and burnoff of marine stratus results in significant costs to the NAS. TMU delay program decisions, based on current forecaster capabilities, err in both directions: holding patterns result from failure to impose or maintain a needed program, and unnecessary delays result from failure to cancel an unneeded program. Operational analysis shows that most of the unnecessary delay and a significant portion of the holding could be eliminated if the TMU were provided with accurate one-hour forecasts of the times of onset and burnoff of marine stratus. The approach taken is to improve the forecasting capability of the CWSU by providing additional weather information that scientists have identified as critical for better forecasts and also to provide an automated forecast guidance system. Although FAA efforts to date have concentrated on specific airports that suffer air traffic delays from reduced ceiling and visibility, there is also significant impact at the national level. Studies to date show that although the greatest benefit is from accurate 1-4 hour forecast products, improvement in underlying technologies may also lead to improved skill in forecasts of up to 12 hours. Beginning in FY01, AWRP is pursuing capabilities for forecast products to alleviate the impact of low ceiling and poor visibility across the National Airspace System. The weather products envisioned will forecast up to 12 hours ahead of the ceilings and visibilities during instrument meteorological conditions on a national level. Benefits to the aviation community: Studies indicate that up to one quarter of the summer delay at SFO would be eliminated by an accurate one-hour forecast of the time of burnoff. A successful product would provide savings of approximately $7M per year at SFO. In addition, the techniques developed will provide the foundation for ceiling and visibility products for several other high-impact coastal airports. Finally, the national ceiling and visibility product will improve safety across the NAS, especially for general aviation users. Below are the links to sub articles on Aviation Digital Data Service:
Ceiling and Visibility
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NASA Headquarters Responsible Official: Code R
Curator: SAIC Information Services http://www.aerospace.nasa.gov |