Ocean Surface Wind Estimation From Waves Based on Small GPS Buoy Observations in a Bay and the Open Ocean. Issue 9 (7th September 2022)

• Record Type: Journal Article
• Authors: Shimura, Tomoya; Mori, Nobuhito; Baba, Yasuyuki; Miyashita, Takuya
• Is Part Of: Journal of geophysical research. Volume 127:Issue 9(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-09-07
• Subjects: ocean wave -- ocean wind -- wave spectrum -- buoy -- observation; Oceanography -- Periodicals; 551.4605
• DOI: 10.1029/2022JC018786
• Languages: English
• ISSNs: 2169-9275

Abstract

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 ${u}_{\ast }{f}^{-4}$ where u ∗ ${u}_{\ast }$ is the friction velocity and f $f$ is the frequency. The determination algorithm for the coefficient of f − 4 ${f}^{-4}$ 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. Plain Language Summary: Ocean observations are spatially sparse compared with on‐land observations because of the difficulty of observation platform development. However, ocean wind and wave information is important in a wide variety of areas, such as coastal disaster mitigation and offshore structure design. Recently, readily deployed small global positioning system (GPS)‐tracked buoys for wave observation have been developed that have the potential to fill gaps in observations through mass deployment. This study proposes a new ocean wind speed and direction estimation method using ocean wave information derived from a small GPS buoy. The performance of the proposed method was validated and compared with data of the observed wind. It was shown that the proposed method can be applied to any type of wave condition, whereas the applicability of the previous method was limited. The proposed method allows for high‐quality ocean wind and wave information to be simultaneously collected. Key Points: Ocean surface wind is estimated from ocean surface wave spectrum information measured by a small global positioning system buoy Ocean surface wind is estimated from ocean surface waves for both bay and open ocean conditions The newly proposed method improves the accuracy of wind speed and direction estimations from ocean surface waves