A simple methodology for surface layer characterization during diabatic extremes
Increased global environmental awareness has fostered widespread use of remote automated weather station (RAWS) networks to monitor meteorological conditions, and reliance on atmospheric dispersion modeling for decisions concerning pollutant dispersion. Dispersion models require as input a characterization of surface layer (SL) heat and momentum fluxes and turbulence. Characterization of these quantities requires the acquisition of flux and variance information as well as the mean winds, temperature, etc. RAWS networks should be designed to provide this information. Rugged and reliable sonic anemometer/thermometers (sonics) most nearly provide the requisite measurement capability. The sonic's capacity to resolve the smallest scales of anisotropic turbulence and the fluxes of heat and momentum is investigated. Measurement deficiencies were found during extreme stable and unstable regimes. A simple methodology for defining turbulence intermittency is presented. This methodology is shown to produce useful results over a wide range of stability, to include stability extremes where reliable Monin-Obukhov Similarity (MOS) estimates are unachievable.
Keywords: Surface layer, Monin-Obukhov Similarity, Automatic Weather Station, Intermittency, isotropic turbulence, sonic anemometer