Sensitivity of Displaced-Beam Scintillometer Measurements of Area-Average Heat Fluxes to Uncertainties in Topographic Heights

摘要

Displaced-beam scintillometer measurements of the turbulence inner-scalelength $l_o$ and refractive index structure function $C_n^2$ resolvearea-average turbulent fluxes of heat and momentum through the Monin-Obukhovsimilarity equations. Sensitivity studies have been produced for the use ofdisplaced-beam scintillometers over flat terrain. Many real field sites featurevariable topography. We develop here an analysis of the sensitivity ofdisplaced-beam scintillometer derived sensible heat fluxes to uncertainties inspacially distributed topographic measurements. Sensitivity is shown to beconcentrated in areas near the center of the beam and where the underlyingtopography is closest to the beam height. Uncertainty may be decreased bytaking precise topographic measurements in these areas.