Representativeness of Wind Observations at Airports

Abstract

Wind information for use at airports can be called representative if it provides an optimal estimate of wind variations to be expected over the runway. It is shown that a single anemometer at a nonideal but reasonable location will usually provide adequate observational data to allow such a representative wind estimate after proper correction and data handling. It follows from the properties of the surface wind field and of the instruments used to measure it that aeronautical wind averaging periods should be at least 2 min for mean winds and at least 5 s for gusts. Small-scale obstacle effects and measuring height variations can be dealt with by an objective exposure correction model. It is shown that the aggregate wind estimation error cannot be less than 10% because of the influence of spatial distance and reporting time lag. The employment of additional anemometers appears justified only by large-scale terrain influences such as mountains or sea breeze-inducing coastlines. Wind information for use at airports can be called representative if it provides an optimal estimate of wind variations to be expected over the runway. It is shown that a single anemometer at a nonideal but reasonable location will usually provide adequate observational data to allow such a representative wind estimate after proper correction and data handling. It follows from the properties of the surface wind field and of the instruments used to measure it that aeronautical wind averaging periods should be at least 2 min for mean winds and at least 5 s for gusts. Small-scale obstacle effects and measuring height variations can be dealt with by an objective exposure correction model. It is shown that the aggregate wind estimation error cannot be less than 10% because of the influence of spatial distance and reporting time lag. The employment of additional anemometers appears justified only by large-scale terrain influences such as mountains or sea breeze-inducing coastlines.