導入氣象觀測資料於GPS網型定位高程精度之研究

Improving Height Precision of GPS Network with Meteorology Observation

楊恩銘(En-Ming Yang) ； 史天元(Tian-Yuan Shih) ； 陳春盛(Chun-Shung Chen) ； 吳俊毅(Jyun-Yi Wu)

《測量工程》 51卷3&4期 (2009/12) Pp. 23-43

https://doi.org/10.29983/JSE.200912.0003

摘要

GPS信號由衛星至地表經過大氣層導致信號的折射及延遲，在對流層當中GPS電磁波之傳遞速率，由於L1及L2兩種頻率的信號之折射量相同，所以GPS觀測時，無法利用雙頻觀測消除折射量。估計對流層延遲量是否精確，成爲影響GPS高程定位精度最大因素之一。
處理對流層延遲量的方法，包含氣象數學經驗模式、對流層參數估計、外部觀測資料改正。在靜態網型定位，通常會以氣象數學經驗模式配合對流層參數估計法來處理對流層延遲量。內政部於雲林縣北港站設有一台水氣微波輻射儀，可觀測此區域對流層延遲絕對量，配合對流層參數估計法可精準預估北港站附近短基線各站的延遲相對值。如此可結合外部改正配合參數估計，探討在台灣濁水溪沖積扇地層下陷區域，對靜態網型定位之坐標趨勢影響。
研究成果顯示，持續地層下陷的客厝站及土庫站加入水氣微波輻射儀資料後，可使高程定位標準差由2.088公分及2.675公分降低至1.092公分及1.321公分。

關鍵字

電磁波 ； 對流層 ； 靜態網形

並列摘要

GPS signals are transmitted from satellite to earth through the atmosphere, causing refraction and delay. The transmission speed of electromagnetic wave changes barely with signal frequency in the troposphere. For this reason, the troposphere delay cannot be eliminated with dual- frequency of carrier phase observation. Therefore, the troposphere delay becomes one of the significant factors for the GPS height accuracy.
Some strategies are frequently used to reduce the troposphere delay, including meteorological experience models, parameter estimation, and external correcting. For the static network computation, empirical meteorological models are usually combined with parameter estimation. On the other hand, the direct meteorological observations may be used for improving the positioning accuracy. This scheme is referred as correction with external observation. The Ministry of Interior has installed one WVR (Water Vapor Radiometer) at PeiKang GPS Station, which can observe the absolute troposphere delay, and predict precisely the relative troposphere delay of each short baseline station nearby PeiKang with parameter estimation.
It is shown that the height standard deviation can be reduced when applied WVR to those continuously subsiding stations. The height standard deviation of KTES GPS Station reduced from 2.088cm to 1.092cm, while TKJS GPS Station reduced from 2.675cm to 1.321cm.

並列關鍵字

Troposhere ； Static Network ； Electromagnet Wave