Turbulent Flux Observations at the Tip of a Narrow Cape on Miyako Island in Japan’s Southwestern Islands

Abstract

Air-sea fluxes were observed to elucidate the lower boundary conditions in the development of an atmospheric boundary layer over sea from 14 to 27 August 2002. Fluxes were observed at the tip of a narrow cape on Miyako Island, in Japan’s Southwestern Islands. Flux measurements and turbulence properties were clearly divided by fetch condition or wind direction. Analysis of the footprint area and homogeneity indicated that air-sea fluxes over an upwind sea surface were observed in cases of approximately 30% for all observation periods. The bulk transfer (BT), eddy covariance (EC), and variance (VA) methods were used to evaluate air-sea fluxes. The general features of the estimated fluxes were similar. Averaged sensible heat flux of approximately 6 W m^-2 was obtained by all three methods, and the latent heat fluxes were 92, 60, and 71 W m^-2 by the BT, EC, and VA methods, respectively. Daily mean net radiation input R_NET was 223 W m^-2. The sea surface was a large energy sink during the observation period.