Comparing Estimates of Turbulence Based on Near-Surface Measurements in the Nocturnal Stable Boundary Layer

摘要

Tethered Lifting System (TLS) estimates of the dissipation rate of turbulent kinetic energy (e){(varepsilon)} are reasonably well correlated with concurrent measurements of vertical velocity variance (s_w2){(sigma_{w}^{2})} obtained from sonic anemometers located on a nearby 60-m tower during the CASES-99 field experiment. Additional results in the first 100 m of the nocturnal stable boundary layer confirm our earlier claim that the presence of weak but persistent background turbulence exists even during the most stable atmospheric conditions, where e{varepsilon} can exhibit values as low as 10−7 m2 s−3. We also present a set of empirical equations that incorporates TLS measurements of temperature, horizontal wind speed, and e{varepsilon} to provide a proxy measurement for s_w2{sigma_{w}^{2}} at altitudes higher than tower heights.