Correction of surface air temperature measurements from a mobile platform

The use of vehicle-borne mobile measurement systems to study processes generating micro-scale temperature variations in the landscape requires precise knowledge of factors influencing the measurements. We reported results from field measurements with a sonic anemometer to determine the how deformation around a vehicle-borne mobile measurement system. These measurements were also used to develop a correction procedure that removes the smoothing induced by the thermal inertia of thermocouples. The procedure is based on Fourier analysis and consists of two components: a low-pass filter that removes noise and aliasing effects above a cut-off frequency and a filter specially designed to remove the effect of the thermal inertia of thermocouple. The correction procedure is applied to two mobile measurement runs acquired during NOPEX CFE1 and compared to sound-virtual temperature recorded at a reference mast. The overall statistics (mean, standard deviation, etc.) are not changed by the correction procedure, but substantial changes occur in the high-frequency part of the observed spectrum that is dominated by turbulent fluctuations during daytime and, during nights, temperature transitions at forest edges and other land-use changes. (C) 1999 Elsevier Science B.V. All rights reserved.