東北亞最高峰玉山正高測量

Determination of the orthometric height of northeast Asia's highest peak ： Mt.Jade(Yushan)

玉山為台灣最高峰，亦是東北亞最高峰，向為台灣精神表徵。其高程3952.348m，係民國六十七年辦理台灣地區三角點測量時，以三角高程測量方法測量結果。台灣地區於民國九十、九十二年分別完成一等一級及一等二級水準網，其中一等二級水準點沿新中橫公路佈設，於玉山登山口塔塔加遊客中心附近設置點號X121水準點，自該點沿登山步道至玉山主峰約14.5公里，內政部土地測量局（以下簡稱本局）於九十二年，完成全線水準測量，並辦理重力測量供正高改正計算，得到目前為止玉山主峰最精密的高程測量成果。玉山正高測量成果係以水準測量逐段高差，加上Heiskanen and Moritz（1967）法正高改正值，求得玉山主峰三角點正高為3951.798公尺，並以各段水準測量往返閉合差作為精度評估之依據，估計本成果精度約為0.072公尺。本作業部分路段尚辦理GPS測量、三角高程測量，供作資料檢核。另考量高山地區地形起伏較大，經以交通大學2002年研究之嚴密平均重力約化法計算正高改正，其結果與Heiskanen and Moritz法有相當差異，且與GPS測量、三角高程測量成果更為相符，這部分亦在文中作一比較分析。 Mt. Jade, or Yushan in Chinese, is the highest peak in Taiwan and east Asia, and is also the spiritual symbol of Taiwan. Its latest published height is 3952.348 m, which was obtained by trigonometric leveling during the establishment of a Taiwan triangulation network carried out in 1978. A new first-order first-class and a new first-order second-class vertical control networks of Taiwan were established in 2001 and 2003, respectively. In the first-order second-class network, benchmarks (BM) along a provincial route near Mt. Jade were deployed and the closest BM to Mt. Jade is X121, which is about 14.5 km to Mt. Jade along a trekking route. In 2003 the Land Survey Bureau (LSB) deployed BM along this trekking route and collected leveling, GPS and gravity data on these BM and computed orthometric correction (OC) for leveling heights. A most precise possible orthometric height of Mt. Jade was obtained. The orthometric height of Mt. Jade was obtained by correcting the differential heights from leveling for OC and is 3951.798 m. The standard error of this orthometric height is 0.072 m, which was based on the misclosures of leveling and the error of OC. GPS and trigonometric data were also collected to verify the leveling result. Because of the complex terrain, a rigorous procedure was used to compute OC, yielding a result that is significantly different from the result computed with the Helmert orthometric correction, but provides orthometric heights better matching the GPS and trigonometric results.

Mt. Jade, or Yushan in Chinese, is the highest peak in Taiwan and east Asia, and is also the spiritual symbol of Taiwan. Its latest published height is 3952.348 m, which was obtained by trigonometric leveling during the establishment of a Taiwan triangulation network carried out in 1978. A new first-order first-class and a new first-order second-class vertical control networks of Taiwan were established in 2001 and 2003, respectively. In the first-order second-class network, benchmarks (BM) along a provincial route near Mt. Jade were deployed and the closest BM to Mt. Jade is X121, which is about 14.5 km to Mt. Jade along a trekking route. In 2003 the Land Survey Bureau (LSB) deployed BM along this trekking route and collected leveling, GPS and gravity data on these BM and computed orthometric correction (OC) for leveling heights. A most precise possible orthometric height of Mt. Jade was obtained. The orthometric height of Mt. Jade was obtained by correcting the differential heights from leveling for OC and is 3951.798 m. The standard error of this orthometric height is 0.072 m, which was based on the misclosures of leveling and the error of OC. GPS and trigonometric data were also collected to verify the leveling result. Because of the complex terrain, a rigorous procedure was used to compute OC, yielding a result that is significantly different from the result computed with the Helmert orthometric correction, but provides orthometric heights better matching the GPS and trigonometric results.