极地空白对GOCE引力场恢复的影响研究

由于倾角大约为96.7°，GOCE卫星的观测值在地球两极附近分别有球冠半径约为6.7°的空白区域。本文结合引力梯度不变量算法，采用球谐分析方法讨论了极区空白对引力场恢复的影响。文中首先推导了空白区对位系数恢复的影响公式，然后通过模拟计算分析了空白区的影响量级和特点。结果表明: 由于正交性遭到破坏,各阶之间会相互影响，特别是对低次的影响比较显著；采用“移去恢复法”可有效解决极地空白带来的精度损失问题，但不同的先验模型会使得最终的解有差异;然而,尽管极区有空白且模型的整体精度将受参考模型的影响，在非极区GOCE仍可提供厘米级的大地水准面。

Research on Influence of Polar Gaps on Gravity Field Recovery Using GOCE Data

There are empty regions near the poles which are two spherical caps with angle radius of 96.7°, as the inclination of GOCE satellite is 96.7°. This paper will discuss the influence by combining the methods of invariants. Firstly it derives the formulas which show the influence of the polar gaps on the gravity field recovery, and then analyzes the magnitude and prosperity of the influence by simulation. The results show that different degrees will influence each other due to the destruction of orthogonality, especially on low orders. The method of remove-restore can effectively solve the problem of accuracy lose due to the polar gaps, but different reference models will give different results. However, even so, GOCE can still provide geoid with accuracy of several centimeters not in polar region.