Instrumentation for high-frequency meteorological observations from research vessel
Abstract
Ship provides an attractive platform from which high-frequency meteorological observations (e.g., wind components, water vapor density, and air temperature) can be made accurately. However, accurate observations of meteorological variables depend on removal of ship motion contamination and appropriate placement of sensors on-board. Vertical and lateral wind components suffer more disturbances than longitudinal wind in consequence of ship motion. Wind stream approaching towards bow gets deflected due to the presence of ship's superstructure that causes error in the wind measurements. It has been reported that underestimation in wind speed owing to the ship's superstructure is approx 7% for bow-on wind and overestimation is approx 10% for relative wind direction of 900. Mean wind speed reduction of approx 8.5% were estimated due to the cylindrical mast when wind flow was parallel to the horizontal plane and excess of approx 9% for the wind flow normal to the plane. The effect of flow distortion on wind was less for relative wind direction of + or -450 relative to the major axis of the ship. In this article, instrumentation used for measuring high-frequency components of meteorological parameters on-board Indian research vessel 'Sindhu Sankalp' and correction of wind for ship motions is described.
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