星载原子干涉技术用于地球重力场测量及其精度评估

Recovery of the Earth's Gravity Field Based on Spaceborne Atom-interferometry and Its Accuracy Estimation

重力梯度卫星GOCE通过搭载静电式重力梯度仪,将全球静态重力场恢复至200阶以上。目前GOCE卫星已结束寿命,亟须发展下一代更高分辨率的卫星重力梯度测量来完善200~360阶的全球静态重力场模型。原子干涉型的重力梯度测量在空间微重力环境下可获得较长的干涉时间,因此具有很高的星载测量精度,是下一代卫星重力梯度测量的候选技术之一。本文针对未来更高分辨率全球重力场测量的科学需求,提出了一种适用于空间微重力环境下的原子干涉重力梯度测量方案,其梯度测量噪声可低至0.85mE/Hz1/2。文中对不同类型的卫星重力梯度测量方案进行了重力场反演精度的对比评估,仿真结果表明,相比于现有静电式卫星重力梯度测量,原子干涉型的卫星重力梯度测量有望将重力场的恢复阶数提升至252~290阶,对应的累积大地水准面误差7~8cm,累积重力异常误差3×10-5 m/s2。

The electrostatic gravity gradiometer has been successfully applied as a core sensor in satellite gravity gradiometric mission GOCE,and its observations are used to recover the Earth＇s static gravity field with a degree and order above 200.The lifetime of GOCE has been over,and the next generation satellite gravity gradiometry with higher resolution is urgently required in order to recover the global steady-state gravity field with a degree and order of 200~360.High potential precision can be obtained in space by atom-interferometry gravity gradiometer due to its long interference time,and thus the atom-interferometry-based satellite gravity gradiometry has been proposed as one of the candidate techniques for the next satellite gravity gradiometric mission.In order to achieve the science goal for high resolution gravity field measurement in the future,a feasible scheme of atom-interferometry gravity gradiometry in micro-gravity environment is given in this paper,and the gravity gradient measurement can be achieved with a noise of 0.85 mE/Hz1/2.Comparison and estimation of the Earth＇s gravity field recovery precision for different types of satellite gravity gradiometry is discussed,and the results show that the satellite gravity gradiometry based on atom-interferometry is expected to provide the global gravity field model with an improved accuracy of 7~8 cm in terms of geoid height and 3×10-5 m/s2 in terms of gravity anomaly respectively at a degree and order of 252~290.