Ocean Surface Wind Estimation From Waves Based on Small GPS Buoy Observations in a Bay and the Open Ocean

Abstract

Ocean surface wind and wave information is important in a wide variety of areas, such as coastal disaster reduction, offshore structure design, and atmosphere-ocean flux estimation. This study proposed a new method for ocean surface wind estimation from surface wave spectrum information measured by small global positioning system buoys. The concept of this method relies on the assumption that the high-frequency part of the ocean-wave spectrum is proportional to u* f⁻⁴ where u* is the friction velocity and urn:x-wiley:21699275:media:jgrc25175:jgrc25175-math-0003 is the frequency. The determination algorithm for the coefficient of f⁻⁴ was optimized in this study. The wind direction was determined by the wave cross-spectrum, assuming that the wind direction aligns the propagation direction of the high-frequency part of the wave. The proposed wind estimation method was applied to bay and open ocean observations, and the performance of the proposed wind estimation method was similar between the bay and the open ocean. The proposed method improves the wind estimation especially in coastal areas and at high wind speeds in the open ocean compared with the previous method. The performance of the method of the previous study differs between the bay and open ocean due to their spectral shape differences. High-quality wind and wave information can be obtained using the proposed method. If the mass deployment of small drifting buoys covered the global ocean, the information based on the proposed method could be considerably powerful, and could compensate for the weakness of satellite-based wind and wave estimations.