近岸海域潮位與波浪觀測用GNSS浮標效能之研究

Performance of the GNSS Buoy for Monitoring Tides and Ocean Waves in Coastal Areas

林演斌(Yen-Pin Lin) ； 黃清哲(Ching-Jer Huang) ； 董東璟(Dong-Jiing Doong) ； 高家俊(Chia Chuen Kao)

《海洋工程學刊》 17卷3期 (2017/09) Pp. 175-177+179-195

摘要

全球衛星導航系統(Global Navigation Satellite System, GNSS)透過內政部國土測繪中心之虛擬基準站即時動態定位(Virtual Base Station Real-Time Kinematics, VBS-RTK)技術解算能獲得公分等級精度的高度資料。本研究主要是探討Lin et al. (2017)利用上述衛星導航系統所研發的近岸海域潮位與波浪作業化觀測用GNSS浮標的效能，如GNSS解算成功率(the percentage of good altitude data)對潮位與波浪觀測結果的影響，以及浮標傾角對潮位與波浪觀測結果的影響等。為探討上述特性，本研究首先進行VBS-RTK服務的解算成功率測試，並分別將GNSS浮標布放於灣裡及小琉球海域，進行現場試驗。試驗結果顯示，GNSS浮標觀測潮位與波浪之有效資料（解算成功率達門檻值以上的資料）比例分別大於83%及74%。在GNSS天線安裝高度為2.26 m的條件下，當浮標平均總傾角小於7°時，潮位誤差基本上可忽略，而當平均總傾角達到16.1°時，未修正的潮位低估12 cm。而以瞬時總傾角修正與否對於示性波高、平均週期與主波向的影響極微。此外，小琉球浮標在試驗期間測到示性波高接近7 m的颱風湧浪，GNSS與加速度-傾角-電羅經(accelerometer-tilt-compass, ATC)波浪儀所觀測到的示性波高非常吻合。

關鍵字

VBS-RTK ； GNSS浮標 ； 近岸海域 ； 潮位與波浪作業化觀測

並列摘要

The Global Navigation Satellite System (GNSS) that utilizes a Virtual Base Station Real-Time Kinematics (VBS-RTK) positioning technology, operated by the National Land Surveying and Mapping Center, Ministry of Interior, R. O. C., can achieve centimeter-level accuracy in measuring elevations. This research aims to examine the performance of the GNSS buoy developed by Lin et al. (2017) based on the above-mentioned GNSS system for monitoring tides and ocean waves in coastal areas. The performance will be examined to clarify the effect of the percentage of good altitude data on the monitoring of tides and waves, as well as the possible errors in the tides and waves that would be caused by the inclination of the buoy hull. First, static test was performed to determine the percentage of good altitude data obtained by the GNSS. Two field tests were carried out by deploying the buoy in the Wan-Li waters and the Small Liu-Qiu waters, respectively, to examine the performance of the GNSS buoy. The field tests demonstrate that the rate of effective data reaches 83 % and 74 % in measuring tides and waves, respectively. The data are referred to as effective data when their accuracies reach centimeter-level. For the field tests with the GNSS antenna installed at an elevation of 2.26 m, as the inclination of the buoy hull is less than 7°, the error in tide caused by the inclination is negligible. However, as the angle increases up to 16.1°, the uncorrected GNSS tide underestimates a water level of 12 cm. The correction of the water level due to inclination does not make significant change in the values of significant wave height, mean wave period, and the peak wave direction. Finally, during the field test, the GNSS buoy deployed in the Small Liu-Qiu waters detected a typhoon-caused swell with a significant wave height up to 7 m. The significant wave height obtained by the GNSS agrees very well with that obtained by the ATC (accelerometer-tilt-compass) wave sensor even at this high wave height.

並列關鍵字

VBS-RTK ； GNSS buoy ； coastal waters ； operational monitoring of tides and waves