Methods are needed to measure the surface fluxes of sensible (H) and latent heat (E) at large scales. A promising method is scintillometry. Over pasture, a near-infrared scintillometer was most sensitive to temperature fluctuations whilst a microwave scintillometer was unduly affected by both humidity fluctuations and correlated temperature-humidity fluctuations. Slower changes in path-averaged humidity caused additional signal variance and an overestimation of H and E. Log-amplitude spectra of the microwave scintillometer signal showed inertial-convective subrange behavior. In combination, path-averaged E and H could be determined over 3 km. Independent corroborative measurements of H and E were made at the path midpoint using the eddy covariance technique. For sensible heat, agreement was within 4% over a measured range 0-300 W m-2, with a residual standard deviation of 45 W m-2. Latent heat agreed at best to within 12% over the range 0-450 W m-2 (residual standard deviation of 94 W m-2) and an offset of 30 W m-2.
|Number of pages||15|
|Journal||Agricultural and Forest Meteorology|
|Publication status||Published - 3 Sep 2001|
- Large scale
- Latent heat flux
- Path average
- Sensible heat flux