Accurate computation of geoid-quasigeoid separation in mountainous region – A case study in Colorado with full extension to the experimental geoid region

IF 0.9 Q4 REMOTE SENSING
Y. M. Wang, M. Véronneau, Jianliang Huang, K. Ahlgren, J. Krcmaric, Xiaopeng Li, D. Avalos-Naranjo
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引用次数: 1

Abstract

Abstract The geoid-quasigeoid separation (GQS) traditionally uses the Bouguer anomalies to approximate the difference between the mean gravity and normal gravity along the plumb line. This approximation is adequate in flat and low elevation areas, but not in high and rugged mountains. To increase the accuracy, higher order terms of the corrections (potential and gravity gradient) to the approximation were computed in Colorado where the 1 cm geoid computation experiment was conducted. Over an area of 730 km by 560 km where the elevation ranges between 932 and 4,385 m, the potential correction (Pot. Corr.) reaches −0.190 m and its root mean square (RMS) is 0.019 m. The gravity gradient correction is small but has high variation: the RMS of the correction is merely 0.003 m but varies from −0.025 to 0.020 m. In addition, the difference between the Bouguer gravity anomaly and gravity disturbance causes about a 0.01 m bias and a maximum correction of 0.02 m. The total corrections range from −0.135 to 0.180 m, with an RMS value of 0.019 m for the region. The magnitude of the corrections is large enough and is not negligible considering today’s cm-geoid requirement. After the test in Colorado, the complete GQS term is computed in 1′ × 1′ grids for the experimental geoid 2020 (xGEOID20), which covers a region bordered by latitude 0–85° north, longitude 180–350° east. Over the land areas, the RMS of the GQS is 0.119 m and the maximum reaches 1.3 m. The RMS of the GQS increases with respect to the height until 4,000 m, then decreases unexpectedly. At the highest peaks (5,500–6,000 m) of Denali and Mount Logan, the RMS of the GQS ranges between 0.08 and 0.189 m. The small GQS at these high peaks are caused by steep slopes around the peaks that produce large Pot. Corr. caused by the topography. In addition, the higher order correction terms reach half of a meter in those peaks.
山区大地水准面-准大地水准面分离的精确计算——以科罗拉多州为例,并全面扩展到实验大地水准面区域
传统的大地水准面-拟大地水准面分离(GQS)方法是利用布格异常近似铅垂线上的平均重力与正常重力之差。这种近似适用于平坦和低海拔地区,但不适用于高而崎岖的山区。为了提高精度,在科罗拉多州进行了1 cm大地水准面计算实验,计算了对近似的高阶修正项(势和重力梯度)。在海拔932 ~ 4385 m的730 km × 560 km范围内,潜在改正量(Pot. Corr.)达到- 0.190 m,均方根(RMS)为0.019 m。重力梯度改正量小但变化大:改正量的均方根值仅为0.003 m,但变化范围为- 0.025 ~ 0.020 m。此外,布格重力异常与重力扰动之间的差异导致了大约0.01 m的偏差和0.02 m的最大校正。总校正范围为- 0.135 ~ 0.180 m, RMS值为0.019 m。修正的幅度足够大,考虑到今天的厘米大地水准面要求,这是不可忽略的。在科罗拉多州进行测试后,完整的GQS项以1 ' × 1 '网格计算实验大地水准面2020 (xGEOID20),该区域覆盖北纬0-85°,东经180-350°的区域。在陆地区域,GQS的均方根值为0.119 m,最大值为1.3 m。GQS的均方根随海拔高度的增大而增大,直到4000 m,然后突然减小。在德纳里山和洛根山的最高峰(5500 - 6000米),GQS的均方根值在0.08到0.189米之间。这些高峰处的小GQS是由山峰周围的陡坡造成的,山峰周围的陡坡产生了大的波束。此外,在这些峰中,高阶校正项达到半米。
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来源期刊
Journal of Geodetic Science
Journal of Geodetic Science REMOTE SENSING-
CiteScore
1.90
自引率
7.70%
发文量
3
审稿时长
14 weeks
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