Spectral Effects on Scalar Correlations and Fluxes

Abstract

A field experiment designed to test sensor separation effects by means of mult iple thermocouple measurements co-located with a sonic anemo meter, a fast gas analyzer and a slow set of CO2 and hu midity sensors is described. The data allo wed the experimental determination of decorrelat ion between scalars, both because of instrumental effects (mostly sensor separation) and physical ones (mostly large-scale ABL processes associated with flu x entrain ment at the top). The large-scale effects are mo re important in terms of the decorrelation they produce, and yet their effect on the measured flu xes is not too large, on account of the high-pass filtering nature of the multip licat ion by the vertical velocity fluctuation, with its inherently higher-frequency range.