Data quality and error analyses of precise leveling observations

• Main Authors: Yu-Te Chou, 周侑德
• Other Authors: Ruey-Juin Rau
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/02967426544784076554

碩士 === 國立成功大學 === 地球科學系碩博士班 === 95 === Abstract We used the precise leveling data of Central Geological Survey from 27 leveling lines in Taiwan between 2002 and 2006 to evaluate the data quality and their accuracy and to construct a procedure for checking the observations and analyzing the systematic errors. The measuring accuracies of about 87% of all single sections are smaller than 1.5 mm √K (K is measures section length, unit for kilometer). Based on our analysis, we found that the error from leveling ruler sinking would accumulate and the correction of this error is between -4.51 and 5.05 mm. In addition, the refraction error and the rod temperature error have significant correction (-1.629-1.519 mm) for systematic errors while estimating the elevation change. The turning point error contributes mainly to the misclosures but not to elevation change. The average misclosure of raw data is 7.3×10-1 mm. After we corrected the raw data according to our procedure, the average misclosure decreases to 1.41×10-3 mm. In the elevation change result, the difference before and after the corrections is 0.72 mm, the maximum value is 4.5mm. The systematic errors can accumulate easily in the mountainous area. If we don’t correct systematic errors, the elevation variation will reach a maximum value of 221.5 mm after 50 years. In regression analyses, the correction parameters refraction error in the plain area is -3.31×10-5 (mm/m3℃) and the correction parameters refraction error in the mountainous area is -4.70×10-5 mm/m3℃. The correction parameters of refraction error in the plain area are different from those in the mountainous area.