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. 1. Definitions and outline of the problem A quest for representativity in observations always implies a definite application of the obtained information. To such a purpose accurate measuring techniques are necessary but not sufficient (Giraytys, 1970). The processing of measured data is equally important to obtain the desired result, namely information that can be applied directly and optimally to the set purpose. When the measurements have to serve several purposes, e.g., aeronautical "nowcasting" and climatology of hourly averages , it will be necessary to gear the directly displayed data to the most pressing application. If, however, the output is strongly adapted towards ease of operational use, then this implies the responsibility to store sufficient original measurements to make reprocessing towards other purposes really feasible. The purpose of airport wind observation is primarily the provision of suitable short-term wind forecasts to pilots engaged in takeoff or landing maneuvers. They must be able to set engine thrust or select a crab angle in optimal anticipation of the wind field that they will encounter during the actual operation within a few minutes of receiving the wind information.

Factors controlling black carbon distribution in the Arctic

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The Effects of Residential Area Building Layout on Outdoor Wind Environment at the Pedestrian Level in Severe Cold Regions of China

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Field Validation of Algebraic Equations for Stack and Wind Driven Air Infiltration Calculations

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