Effects of Airflow Trajectories Around Aircraft on Measurements of Scalar Fluxes

Abstract

Potential-flow calculations of the airflow around two research aircraft are used to estimate the effect of flow distortion on measured fluxes of sensible heat and water vapor. From the calculated flow patterns, flow-distortion coefficients are determined and used to characterize biases and contamination terms in the measured fluxes. These calculations provide the basis for estimating the magnitude of the errors and in some cases for correcting the measurements. The errors in measured fluxes for typical mid-day planetary boundary layers are usually less than 5%, if the normal choices for sensor locations are used, but could be much larger for other possible locations. The estimated errors for realistic measurement conditions are smaller than statistical uncertainties in the flux estimates for those same flight segments, when the flight legs are about 10 min in duration.