垂线偏差测量的固体潮和海潮改正

垂线偏差是大地测量学和地球物理学的基础数据。固体潮和海潮是影响高精度垂线偏差测量的重要因素,固体潮改正主要表现为天体引潮位对垂线偏差的直接影响及造成地球形变而产生的附加位对其的间接影响。本文基于引力场球谐展开理论,推导了垂线偏差测量中固体潮和海潮的改正公式。利用JPL DE421星历和EOT11A海潮模型,计算全球19 570个GNSS测站处垂线偏差的潮汐改正值,分析了垂线偏差潮汐改正的时空变化规律。通过实例给出了日、月引潮位及附加位、海潮对垂线偏差子午和卯酉分量的改正。现有高精度垂线偏差测量精度已达到0.1″,而固体潮和海潮对垂线偏差的改正总量级可达我国一等天文规定精度(0.3″)的17%,因此在高精度的垂线偏差应用中需要顾及潮汐改正。

Corrections of solid earth tide and ocean tide for measurement of deflection of the vertical

The deflection of the vertical (DOV) is the basic data for geodesy and geophysics. The solid earth tide and ocean tide are important factors affecting the precision of DOV measurement.The correction of the solid earth tide mainly includes the direct effect of celestial tidal-generating potential on the DOV, and the indirect effect of additional gravitational potential caused by solid earth deformation.Based on the spherical harmonic expansion theory of the gravitational field, this paper deduces the correction formulae of the solid earth tide and ocean tide for DOV measurement. Using JPL DE421 ephemeris model and EOT11A tide model, the DOV corrections on 19570 GNSS stations all over the world were calculated, and their temporal and spatial variations were then analyzed. The corrections of tidal-generating potentials of solar and lunar and its additional gravitational potentials, and ocean tide for the meridian and prime vertical components of DOV are given bythe examples. The updated precision of DOV measurement can reach the level of 0.1″, however, the DOV corrections of the solid earth tide and the ocean tide account for about 17% of the first-class astronomical accuracy (0.3″) in China. It must be taken into account the corrections of solid earth tide and ocean tide in the applications of precise DOV.