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Abstract: To cover the increased demand of renewable energy the development of offshore wind turbines that can be placed in deep water has started. Model results from Sullivan et al. [2] indicate that the ocean has the ability to interact with the lower part of the Marine Atmospheric Boundary Layer (MABL). This leads to turbulent horizontal and vertical motions of the air that potentially reduces turbine lifetime and energy reliability. This paper gives a description of the Norwegian Center for Offshore Wind Energy (NORCOWE) direct covariance flux system. Consisting of a sonic anemometer, a state-of-the-art inertial measurement unit (IMU) and a data logger the system can easily be mounted on all floating platforms, e.g. ships or buoys and operates autonomously. This will in the future enable researchers to investigate turbulent motion and turbulent momentum transport processes in the MABL in more detail. [Copyright &y& Elsevier]

Abstract: In this paper, we present the air–sea flux of momentum obtained with the eddy correlation method applied to data measured from a moored discus buoy deployed approximately 600 m off a research Air Sea Interaction Tower at Martha's Vineyard Coastal Observatory, Massachusetts during spring 2010. We discuss corrections to account for the wave–induced motion of buoy. Our analysis confirm that the neutral drag coefficient depends upon wave age and wind speed. The data scatter between wind and momentum stress in the low wind speed are significantly larger for those with higher wind speeds. Furthermore, the momentum transfer is investigated using a wave model with sea state dependent drag coefficient. This wave age dependent drag reveals fairly good agreement compared to the observed drag coefficient. [Copyright &y& Elsevier]

Abstract: Understanding of the turbulent exchange processes between the ocean and the overlying atmosphere is essential for wind shear and turbulence structure of the Marine Atmospheric Boundary Layer (MABL). This is highly relevant for the development of offshore wind projects with respect to the expected power output and acceptable structural loads and fatigue of turbines. This paper presents preliminary results from a recent field experiment off the coast of Martha''s Vineyard, Massachusetts. Turbulent fluxes have been measured from both a discus buoy and the Air Sea Interaction Tower (ASIT). Using the correction algorithm of Edson et al. (1998) the buoy data are corrected and compared with the ASIT measurements. The comparison shows that the corrected fluxes measured from the mooring are in good agreement with measured fluxes from the tower and that the direct covariance flux method is applicable for offshore turbulent flux measurements. [Copyright &y& Elsevier]