Air motion measurements from aircraft: a historical perspective and contributions to current understanding

Measuring the velocity of the air from an aircraft poses many problems because of the mobility of aircraft. The history of air motion measurement goes back to the 1950's with pioneers such as Andrew Bunker, Paul MacCready, and James Telford. Major technological advancements that enabled accurate measurements occurred in the early 1960's with the development of inertial navigations systems and in the 1990's with the development of GPS. Early aircraft systems could measure fluctuations in wind velocity and mean horizontal wind, but mesoscale wind fluctuations were more problematical. Douglas Lilly saw the potential for improved aircraft air-motion measurements in the 1960's and encouraged the development of systems to accomplish this. This led to a series of field studies involving orographic flows, and turbulence structure of clear and cloudy boundary layers. Recent developments include the potential for measuring divergence and vorticity on the mesoscale, the availability of fast chemical tracer sensors for measuring entrainment, and the use of radars and lidars for turbulence measurements.