综合利用海岸带GNSS水准和重力数据精密确定中国高程基准偏差

Precise Determination of National Height Datum Discrepancy from Combination of GNSS/Leveling and Gravity Data in Coastal Areas of China

综合利用中国海岸带GNSS水准和多源重力测量数据,通过精化陆海统一的重力似大地水准面计算高程异常零阶项,精密确定了中国1985国家高程基准相对于重力大地水准面的偏差。结果显示:中国1985国家高程基准相对于国际地球自转服务(International Earth Rotation Service,IERS)的IERS2010标准W_0对应的重力大地水准面的偏差为30.4±1.0cm;中国1985国家高程基准于20世纪80年代经琼州海峡传递到海南岛后,在1cm精度水平上未发现明显差异;计算的重力似大地水准面经全球导航卫星系统(globa navigation satellite system,GNSS)水准外部检核,标准差约为4cm,12个省市和陆海交界处在厘米级精度水平上无缝衔接。在近10a内,天津市除西北角外,大部分地区存在地面下沉,东南部地面下沉约7cm,上海市地面下沉约7cm,浙江省、江苏省和福建省等沿海省份局部地区也出现地面下沉。

A seamless coastal gravimetric quasi-geoid model was computed using a combination of heterogeneous gravity data.A comparison to the precise GNSS/leveling derived height anomalies,accurately determined the discrepancy of the 1985 national height datum with respect to the gravimetric quasi-geoid.Based on the numerical results,the discrepancy of the 1985 national height datum with respect to the gravimetric quasi-geoid with W_0 defined by IERS2010 standard is 30.4±1.0 cm.After transmitting the 1985 national height datum to Hainan Island through the Qiongzhou Strait in 1980 s,the regional height datum of Hainan Island showed no significant bias at the 1 cm accuracy level.The standard deviation of the differences between the GNSS/leveling derived height anomalies and the computed quasi-geoid model was 4 cm.The quasi-geoid is seamless across the borders of the 13 provinces and cities.Research findings show that during the last ten years,land subsidence is extensive over most areas of Tianjin except for its northwest corner,where the land subsidence over southeast area reaches up to 7 cm.The land subsidence of Shanghai is about 7 cm,and there are various degrees of land subsidence in some parts of Zhejiang,Jiangsu and Fujian as well.