Improving Wind Velocity Measurements on Ships: Industrial Training year at the James Rennell Centre for Ocean Circulation, 12 Aug 1993 - 9 Sept 1994

Accurate wind speed measurements are required from Research vessels for satellite validation and climate research, but the results have been shown to differ significantly from ship to ship. This report discusses an attempt to find the cause of the discrepancies and, if possible, to correct for them. A study on wind speed errors was undertaken to study the airflow distortions around a ship using numerical modelling. Simple potential models were used to study the airflow distortions around an idealised cylindrical mast to fmd the effect of the ship's mast on anemometers positioned close to it. The wake potential model was applied to wind speed data from RRS. Charles Darwin cruise 43 and partially corrected the wind speed measurements from anemometers at 5 to 6 mast diameters. The airflow distortions over the ship's hull and superstructure were then investigated to try to account for these remaining wind speed errors. Wind speed errors were calculated using a Computational Fluid Dynamics (C.FD.) package and computer generated ship models. The study is in a preliminary stage and the C.F.D. package has been validated against a wind turmel study for the C.S.S. Dawson and wind speed corrections agree to within 2 %