12th Conference on Interactions of the Sea and Atmosphere


Air-sea interaction processes observed from buoy and propagation measurements during the RED Experiment

Paul A. Frederickson, NPS, Monterey, CA; and K. L. Davidson, K. D. Anderson, S. M. Doss-Hammel, and D. Tsintikidis

The Naval Postgraduate School (NPS) deployed its research ‘flux’ buoy off Oahu, Hawaii, during the recent Rough Evaporation Duct (RED) Experiment conducted in August-September 2001. The buoy was moored at the midpoint of a 10 km optical transmission path between the Research Platform FLIP and the Oahu coast. Microwave propagation measurements were also made from FLIP along a different path. Measurements of mean meteorological properties, air temperature and humidity at four height levels, direct turbulent fluxes and surface wave characteristics were obtained from the flux buoy simultaneously with optical transmission and scintillation data. These data provide excellent information for examining air-sea interaction phenomenon, such as surface wave effects on fluxes, vertical profiles and aerosol concentrations, as well as the resulting effects on optical and microwave propagation.

The near-horizon propagation data themselves are useful for providing information regarding the characteristics of the marine atmospheric surface layer. For example, near-horizon microwave propagation depends primarily on the vertical humidity and temperature structure in the lower atmosphere. Optical propagation depends primarily on the vertical temperature profile, turbulent intensity and aerosol concentrations along the path. Therefore, having simultaneous meteorological and propagation data available provides more complete information for air-sea interaction studies than the sum of the two measurement components obtained individually.

In this presentation we will examine the applicability of Monin-Obukhov similarity (MOS) theory scaling over the wavy ocean surface in terms of structure parameter functions and vertical scalar profiles. Direct turbulence measurements of the temperature scaling parameter, CT2, will be compared with estimates obtained from mean meteorological measurements using MOS-based bulk models and optically-derived Cn2 observations, to attempt to determine under which meteorological and surface wave conditions MOS scaling is valid and when it begins to break down. The near-surface profiles of temperature and humidity will be examined using the directly measured profiles obtained on the NPS buoy, as well as information gleaned from the microwave and optical propagation data. The surface wave spectra data obtained from the flux buoy will be used to determine the possible effects of ocean waves in modifying MOS scaling theory from the traditional forms derived from over-land observations.

extended abstract  Extended Abstract (500K)

Session 9, RED SEAS Experiments
Thursday, 13 February 2003, 8:30 AM-2:15 PM

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