絕對重力監測點作為臺灣重力基準之研究

Study on Absolute Gravity Monitoring Stations for Taiwan Gravity Datum

李瓊武(Chiung-Wu Lee) ； 謝文祺(Wen-Chi Hsieh) ； 黃鉅富(Jiu-Fu Huang) ； 高瑞其(Ricky Kao) ； 彭淼祥(Miao-Hsiang Peng) ； 黃金維(Chein-Way Hwang) ； 陳杰宗(Jie-Zong Chen)

《地籍測量：中華民國地籍測量學會會刊》 28卷3期 (2009/09) Pp. 51-58

https://doi.org/10.29609/YYWYLL.200909.0004

摘要

1971年國際重力基準網(I.G.S.N.71)以多點基準取代單點1909年波茨坦重力基準，至現在正著手建置高精度（±10μGal或更好）的國際絕對重力基本網(IAGBN)，其主要任務是長期監測重力隨時間的變化，其次是作為重力測量的基準，及不同重力儀比對。因此，這些絕對重力點建立後，間隔數年後須進行重複觀測。內政部自2003年陸續購置兩部絕對重力儀FG5，在臺澎金馬地區（含蘭嶼及綠島）設置絕對重力監測點，實施絕對重力量測，作為重力測量引測重力之用。為此，2005年曾將絕對重力儀FG5運至巴黎國際度量衡局(BIPM)，參加國際絕對重力儀比對活動(ICAG-2005)，評估量測不確定度，藉以確保我國絕對重力量測能力與國際水準一致。而本文參考國際標準組織(ISO)量測不確定度表示指引，評估絕對重力監測點在95%信賴水準及擴充因子2.0下，其擴充不確定度約8μGal，預期可成為國際絕對重力基本網(IAGBN)之一，並作為國家重力基準及國家重力系統之主要依據。

關鍵字

絕對重力儀 ； 擴充不確定度 ； 國際絕對重力基本網 ； 重力基準

並列摘要

The International Gravity Standardization Net 1971 (I.G.S.N.71) with more gravity datum has been used to replace the Potsdam gravity system 1909 with only one basis. The International Absolute Gravity Basestation Network (IAGBN) with high precision (±0.1 μm s^(-2) or better) is scheduled to be established. The main purpose of the network is to monitor temporal gravity changes. Besides, the stations of the network are able to be served as a basis of regional gravity surveying and to function as reference stations for tests and comparisons of different gravimeters. Therefore, the stations of the network are required to be measured repeatedly at a certain interval.
Ministry of Interior has owned two absolute gravimeters of FG5 since 2004. The absolute gravity monitoring stations measured with them have been carried out over the area of Penghu, Kinmen, Matsu, Lanyu, Green Island and Taiwan for these years, which are serving as a basis for relative gravity surveying. For the quality assurance program, the team with the Absolute Gravimeter FG5-224 in the name of Chinese Taipei took part in the ICAG-2005 campaign at BIPM in Paris for verifying the measurement uncertainty of the absolute gravity. The result showed that our competence in absolute gravity measurement is identical to the international level. The expanded uncertainty of the absolute gravity monitoring stations are evaluated to be around 8 μGal, in accordance with the ”Guide to the Expression of Uncertainty in Measurement” published by ISO and under the confidence level of 95% and coverage factor of 2.0. Those stations are expected to act as a part of the IAGBN and the gravity datum for the National Gravity System in Taiwan.

並列關鍵字

Absolute Gravimeter ； Expanded Uncertainty ； IAGBN ； Gravity Datum