Upgrade and Technology Transfer of the San Francisco Marine Stratus Forecast System to the National Weather Service

The regular summer season occurrence of marine stratus at San Francisco International Airport (SFO) often prohibits dual parallel approaches of aircraft to the closely spaced parallel runways, effectively reducing 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. 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.

The FAA's Aviation Weather Research Program (AWRP) sponsored the development of a demonstration Marine Stratus Forecast System, which was used as a real time tool for anticipating the time of stratus clearing. 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 CWSU at Oakland Center. The system relied on a network of field-deployed sensors in the San Francisco Bay region, as well as conventional surface observations and satellite data from the Geostationary Operational Environment Satellite (GOES-10). Data were collected, processed, and input to a suite of forecast models developed to predict the stratus clearing time. Both the data observations and the forecast model guidance were delivered to users on an interactive display accessible via the Internet. The primary users of the system were forecasters responsible for providing guidance for air traffic management purposes, both in the public and private sectors.

Working with the National Weather Service (under the leadership of the Weather Service Forecast Office in Monterey), system specifications were developed in 2003 for an upgraded version of the system that would meet NWS requirements of reliability and performance, such that the NWS would agree to adopt responsibility for operation and maintenance of the system. During the winter of 2003-2004, a major upgrade, reconfiguration, and stabilization of hardware, communications, security, and software was performed, with the hardened system placed back on line by late June 2004. Operations ran throughout the remainder of the 2004 stratus season, as operational and maintenance responsibilities were gradually transitioned from the development team to the NWS.

The system continued to collect and display observational data throughout the 2004-2005-winter season with downtime limited to field-site maintenance. Under the direction of the NWS, forecast guidance for the 2005 stratus season resumed in mid-May. This presentation provides an overview of the upgraded system, a review of recent forecast performance, and a discussion of the impact forecast guidance has had on decision-making within air traffic management.