After a major hurricane strikes the U.S. coastline, scientists at NOAA's Hurricane Research Division (HRD) in Miami have spent months to years reconstucting the wind fields. According to the Dr. Mark Powell, lead scientist on the project, "We've analyzed every major hurricane to strike the U.S. since Hurricane Frederic hit the Gulf coast in 1979. We have to go out into the field and carefully examine the terrain surrounding each weather station and correct the readings". Objective documentation of hurricane wind fields are important for establishing whether the winds exceed risk levels for building design. The wind analyses also help establish the extreme wind climate for a local area which in turn feeds into the price of insurance. Powell, and his colleague Samuel Houston, who recently completed a reconstruction for Super Typhoon Paka which hit Guam in 1997, have taken the techniques they developed for storm wind field reconstruction to create a system to analyze hurricane surface winds in real time. With the help of computer scientists and research grants from NOAA's High Performance Computing and Commnications Program and the National Institute for Building Sciences they are now modernizing the system into a JAVA program that brings in weather observations from reconnaissance aircraft, research aircraft, satellites, ships, buoys, and island airports. These disparate data are processed to a common height and averaging time. A scientist examines and evaluates the data as they come in and then sends it to be objectively analyzed by another computer. The resulting product, a streamline and wind speed contour map, shows the location and extent of the strongest winds in the storm as well as the coastal geography. The product is then given to hurricane forecasters at the National Hurricane Center as guidance for their warnings and advisories, and placed in the storm atlas of the HRD web page (www.aoml.noaa.gov/hrd).
This works great as long as the storm is offshore. Once the storm begins to cross the coast, the winds become greatly reduced by terrain and structures, and it is important to correct them to a common exposure to represent a conservative estimate for the highest winds over open land areas. For example, Powell, Houston, and civil engineering colleague Dr. Tim Reinhold of Clemson University documeted wind observations from Hurricane Andrew in 1992 that doubled when flowing from an area with trees and buildings to an open area. To be able to account for these effects, the scientists need to visit and document the wind measurement sites (not possible in realtime) or be able to access a catalog of documented site exposures for weather stations.
In 1997 Powell approached Anne Lazar of the National Climatic Data Center and the National Weather Service's Rainer Dombrowski (ASOS Program Office) and Dave Gilhousen (National Data Buoy Center) about creating an electronic digital photo catalog. In 1998 Powell received a research grant from the U.S. Weather Research Program's Severe Weather Initiative to help fund the project to create a catalog of wind exposure documentation photos for Automatic Surface Observing Stations (ASOS) and Coastal-Marine Automated Network (CMAN) sites. A web page describing the project is located at www.aoml.noaa.gov/hrd/asos. Digital cameras were distributed to 35 National Weather Service Forecast Offices and Data Aquisition Program Managers (DAPM's) and electronics technicians conducted field visits to over 300 weather stations during normal maintenance schedules. These stations cover states and territories bordering the Atlantic, Gulf of Mexico, and Pacific including Hawaii, Puerto Rico, the Virgin Islands, and Guam. Midway through the 1999 Hurricane season, about half of the sites have completed documentation. The National Climatic Data Center has placed ASOS station photos and text and audio exposure descriptions of the sites on their web pages at www.ncdc.noaa.gov. The National Data Buoy Office has placed similar information for C-MAN sites on their web site at www.ndbc.noaa.gov.
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