Determination of Turbulent Sensible Heat Flux over a Coastal Maritime Area Using a Large Aperture Scintillometer

Abstract

Scintillometers have been widely used in estimating the surface-layer sensible heat flux $(Q_\mathrm{H})$ over natural and urban surfaces, but their application over water bodies is rare. Here, a large aperture scintillometer (LAS) was deployed over a coastal maritime area (‘a beach’) with an optical path distance of 1 km to investigate LAS capability in estimating the sensible heat fluxes. The measurements were conducted for clear days in the cold season, characterized by a warmer sea surface than the overlying air throughout the studied days. The LAS-derived $Q_\mathrm{H}$ showed a significant diurnal variability of 10-150 W m$^{-2}$ at the coastal site, and it was found that local thermal advection and tidal change at the site largely influenced the diurnal variability. A series of sensitivity tests indicated that the uncertainty in the LAS-derived $Q_\mathrm{H}$ was less than 11 %, except when De Bruin’s similarity function was used. The overall results demonstrate that the LAS system can detect the magnitude and variability of the turbulent heat exchange at the coastal site with high temporal resolution, suggesting its usefulness for estimating $Q_\mathrm{H}$ in the coastal maritime environment.