The Dulles Airport Pressure Jump Detector Array for Gust Front Detection

Wind shear has long been recognized as one of the major aviation hazards in the airport environment. A principal source of dangerous wind shear is the thunderstorm gust front, a cold air outflow from the thunderstorm downdraft. The gust front is particularly hazardous not only because of the large surface wind shears associated with it, but also because of its highly localized character. Often the downdraft or downburst region producing such fronts is of the order of a few kilometers or less in dimension. As a result, vertically profiling wind shear detection techniques such as the hybrid acoustic–microwave radar system described in the companion paper by Hardesty et al. (1977) do not provide adequate total protection. In this paper we describe an array of pressure sensors installed at Dulles International Airport in Washington, D.C., to detect and monitor gust fronts that could endanger aircraft operations. The pressure sensors (designed to respond only to sudden pressure increase) are so inexpensive that they can be used in dense networks of large spatial extent to monitor in detail the gust front progress as it approaches the airport. Some 125 sensors have been installed at Dulles. Indeed, a major cost of the installation is the cost of the phone lines required to return the information to a central data-processing location. The system has been operating unattended for extended periods of time, registering the frontal passages that have also been detected by the acoustic–microwave radar system as they pass overhead. Results are presented showing the complementary nature of the two monitoring methods.