Abstract

A suite of instruments was deployed to assess the ability of scintillation techniques to measure the fluxes of heat and momentum in the atmospheric surface layer. The experiment took place over horizontally homogeneous terrain. The intensity variances were measured simultaneously from a laser beam received through a 1-mm aperture and from a large-aperture scintillometer. The ratio of these variances gives the inner scale l₀. Knowing l₀, either variance gives ${\text{C}}_n^2$ Monin-Obukhov similarity theory relates heat and momentum fluxes to ${\text{C}}_n^2$ and l₀. A three-axis sonic anemometer and resistance wire thermometer were used to provide in situ measurements of these fluxes. Good agreement was obtained. Spaced hot film anemometers measured the velocity structure parameter, from which an in situ value of l₀ was obtained. Optical scintillation was the superior method of obtaining l₀. An optical scintillation crosswind meter was also deployed. Its axis was oriented vertically to measure the net vertical drift of rising, hot, turbulent air. These measurements correlated with heat flux for very unstable conditions. Also, ${\text{C}}_n^2$ scintillometers were operated at two heights.

© 1989 Optical Society of America