利用多元資料評估臺灣深度基準及深度系統之精度

近年來隨著海洋空間規劃、國土劃界以及電子航行圖測製與發行等發展需求，內政部已完成我國深度基準及深度系統建置，模式內容包含台灣周圍海域無縫5個潮位面、新版大地起伏模型、平均海水面網格模型以及高精度MOI.18v1潮位模式，能提供陸海域數據於不同垂直基準面間進行相互轉換。本研究利用臨時潮位站、全球導航系統（Global Navigation Satellite System, GNSS）浮標以及船測水深資料等多元測繪資料分析臺灣深度基準及深度系統之精度。成果顯示，臨時潮位站資料（港內）和龍洞GNSS浮標（港外）分別與MOI.18v1潮位模式之正高以及約最低低潮位面（Indian Spring Low Water, ISLW））水位高比較，其差值均方根誤差為0.20~0.22 m（港內/正高）、0.14 m（港外/正高）以及0.12~0.14 m（港內/ISLW），而MOI.18v1潮位模式於港內和港外之精度分別為0.10~0.11 m和0.13 m。另外，水深資料轉換至橢球高、ISLW與正高等基準面，並與船測公司成果相比較，各基準差值平均值和標準偏差之平均值範圍分別為-0.225~0.177 m和0.130~0.226 m，表示水深資料和深度基準及深度系統之基準面間約有10~20 cm差異。

In recent years, in order to fulfill the requirement for the development of marine spatial planning, boundary demarcation, and the survey and publication of electronic navigational charts, the Ministry of Interior has established a depth datum and system for Taiwan, including five seamless gridded tidal surfaces, an updated geoid undulation model, a gridded mean sea surface model, and a high-precision MOI.18v1 ocean tide model, allowing users to convert land/sea data to shift elevations/depths from one vertical datum to another. The study analyzed the accuracy of the depth datum and system for Taiwan using multi-data, including temporary tide gauge records, Global Navigation Satellite System (GNSS) buoy, and shipboard bathymetric data. Results showed that the root mean square errors of the differences between the observed data from the temporary tide gauge records (inner harbor) and the GNSS buoy (outer harbor) in Longdong, respectively, and the water levels of MOI.18v1 ocean tide model above a geoid and Indian Spring Low Water (ISLW) were 0.20-0.22 m (inner harbor/orthometric height), 0.14 m (outer harbor/orthometric height), and 0.12~0.14 m (inner harbor/ISLW height). The accuracy of the MOI.18v1 ocean tide model is 0.10~0.11 m for inner harbor and 0.13 m for outer harbor, respectively. Furthermore, bathymetric data were converted to ellipsoidal, ISLW, and orthometric datums, respectively, and then compared with the hydrographic survey results. The mean differences of individual datums and the mean standard deviations were -0.225~0.177 m and 0.130~0.226 m, respectively, indicating that there is a difference of about 10~20 cm between the bathymetric data and the depth datum and system for Taiwan.