Collecting and processing the data follows a circuitous route. The NWS automatically polls and collects observations from many of the sites hourly and updates the Automated Local Event Reporting in Real-Time (ALERT) file. A PC in the Meteorology Department at San Jose State University (SJSU) polls the ALERT file and other stations by phone modem. These data files include much text that must be processed to get formatted files for the wind calculations. The raw data files are transmitted over an ethernet connection to a workstation at SJSU, and from there via dedicated digital phone line to a workstation at the Center Weather Service Unit (CWSU) in Fremont, California. The CWSU workstation ftp's raw data to a PC that removes the text and creates files that can be used for the computer calculations. The same PC that removes the text also calculates winds for display and use with satellite cloud images to aid in the forecasting of stratus onset and clearing for air traffic control purposes.


Wind and stratus display used at the CSWU




The data routing originally ended at this point, because its purpose was to assist forecasters.  Later, the U. S. Geological Survey SFPORTS program learned of its existence and decided that such wind information had the potential to be useful in their studies of the Bay's currents . Now, the PC at the CSWU also transmits the input data files back to the SJSU workstation, which then sends the ready-to-use data to a web-server workstation at the USGS Western Regional Office in Menlo Park via an internet connection. The USGS workstation used the data to calculate winds(Next Page) for the Bay Area and to display them.  In 2008, the process was shortened by installing a duplicate site at the San Jose State University Meteorology Department.

A complete (and more scientific) description of the procedure by which the winds are calculated was published by F. L. Ludwig , J. M. Livingston, and R. M. Endlich in 1991 in the Journal of Applied Meteorology (Volume 30, No. 11, pp.1490-1499). The article's title was, "Use of Mass Conservation and Critical Dividing Streamline Concepts for Efficient Objective Analysis of Winds in Complex Terrain."

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