Interactions Between Heterogeneous Terrain and Atmospheric Fluxes

The determination of surface heat fluxes over heterogeneous terrain benefits from a spatial averaged measurement, such as scintillometry, as opposed to traditional temporal averaged techniques. We seek experimental evidence for the effects of mild heterogeneity on the measurement of the refractive index structure parameter (C_n²) and the sensible and latent heat fluxes. Measurements are obtained from a two-wavelength (near-infrared and microwave) scintillometer system, Scintec BLS900 and Radiometer Physics GmbH MWSC-160, and three eddy covariance (EC) stations located along the beam path of the scintillometer. Comparisons are made between the estimated measurement footprints, meteorological structure parameters for temperature (C_T²) and specific humidity (C_q²), as well as other metrics to quantify the effects of surface heterogeneity on spatially averaged measurements. To further analyze the hydrologic cycle, measurements of area average soil moisture from observations of ground level fast neutron fluxes are compared to EC and scintillometer moisture fluxes. The presented data aims to increase the confidence in interpreting atmospheric fluxes from electromagnetic wave propagation in more complex and sensitive environments. Additionally, conditions under which the scintillometer system performs poorly are discussed.