東沙潮位站設施與運作

The Establishment of Dongsha Tidal Station

本文所記述之東沙潮位站設置於東沙環礁東沙島上，為由「中央氣象局」在東沙新建碼頭施工前規劃設計，內政部委由國立交通大學建置。本站於民國98年底初次完成開始運作，民國107年進行井內固定架與太陽能板重建，其間歷經定期保養與數次儀器更換。本站感測端位於東沙島南岸新建碼頭靜水井內，面向環礁潟湖，採用Druck PTX 1830壓力式感測器，Rixen Sentron溫度計，觀測水壓與水溫。記錄端位於漁民服務站文康室內，GPS定時天線設置於漁服站屋頂近樓梯處，太陽能板設置於漁服站水塔頂。感測端與記錄端間以訊號線相連結，訊號線長度為200公尺。基於降低類比訊號衰減之考量，訊號線與感測端一體成型。潮位站水壓經由換算得瞬間觀測水深，再經由支距常數量測及直接水準測量與東沙島正高系統連接。本站觀測頻率為每秒一筆，同時產出每秒一筆（S檔）與每六分鐘一筆（T檔）觀測記錄。 The tidal station documented in this article is located in Dongsha island of the Dongsha atoll. This tidal station was designed by the Central Weather Bureau prior to the construction of the new wharf in Dongsha. The Ministry of Interior implemented this tidal station in 2009, in conjunction with the National Chiao Tung University. This station became operational by the end of 2009. In 2018, a major re-construction was conducted including that of the fixture frame inside the stilling well. Regular maintenance was carried out routinely, with periodic sensor and equipment replacement. Two major sensors, Druck PTX 1830 pressure sensor for measuring sea surface height, and Rixen Sentron thermometer for sea temperature, were installed inside the stilling well located at the wharf. The relevant data logger for these sensors is located in the Service Center of Fishermen. A GPS timing device is used to keep track of time. The antenna of this GPS device is located on the roof of the building, in close proximity to the ladder. Solar panels are installed on the top of the water tower which is located on the roof of the ser building. Signals from the sensors were transmitted via cable from the wharf to the loggers In order to reduce the noise level resulting from the transmission, a 200 m cable is consolidated with the sensor. The water pressure measured is converted to depth. Then the height of sea surface at the time of observation is linked with the orthometric height through the offset measurements and the direct levelling. The frequency of observation is one Hertz. Both the S file (every one second) and the T file (every six minutes) are recorded.