近二十年,GRACE/GRACE-FO实现了对地球时变重力场的连续监测.但受单极轨轨道配置、背景模型误差和载荷精度的限制,其时空分辨率和观测精度不足以探测短时间、小尺度的质量变化信号.以欧空局MAGIC(Mass Change and Geoscience International Constellation)和中山大学"天琴计划"为代表的下一代重力计划将通过多对卫星星座和新一代高精度载荷来提高时变重力场反演精度.考虑到未来多项卫星重力计划和当前GRACE-FO、中国重力卫星同期观测的可能,本文基于动力学方法对双极轨、Bender、极轨+Bender和双Bender四种星座构型进行了闭环仿真模拟,并对其月尺度解和1～3天短周期解进行评估.结果表明:(1)相较于单极轨,双极轨、Bender、极轨+Bender和双Bender四种星座的月尺度时变重力场恢复精度分别提高了 30.7％、85.7％、85.9％和89.5％.(2)多对卫星星座能够恢复高空间分辨率的短周期时变重力场解,且在时间序列中能够保留地球物理信号的高频部分.其中双Bender能够恢复40阶的1天解时变重力场,极轨+Bender能够恢复40阶的2天解时变重力场,Bender能够恢复40阶的3天解时变重力场.
A simulation study on uncertainties and spatio-temporal resolutions of time-variable gravity fields based on multiple GRACE-like constellations
In recent two decades,GRACE/GRACE-FO has continuously monitored the earth's time-variable gravity field(TVG).However,limited by a single-polar orbit configuration,background model errors and the accuracy of satellite payloads,the spatio-temporal resolution and accuracy of TVG are insufficient to detect short-term,small-scale mass change signals.The next-generation gravity missions(NGGMs),represented by ESA's MAGIC(Mass Change and Geoscience International Constellation)and SYSU's"TianQin",will improve the accuracy of the recovered TVG through multi-pair satellite constellations and the new generation of high-precision satellite payloads.Considering the possibility of synergistic observation for future gravity missions,GRACE-FO and the Chinese gravity mission,this paper performed closed-loop simulations based on four constellations:2Polar,Bender,Polar+Bender and 2Bender with the dynamic method.The solutions based on these different simulations are evaluated on one-day,two-day,three-day and monthly time scales.The results show that compared with the single-polar,the accuracy of monthly TVG for 2Polar,Bender,Polar+Bender and 2Bender is increased by 30.7％,85.7％,85.9％and 89.5％,respectively.The multi-pair satellite constellations can recover short-term TVG with high spatial resolution and retain the high-frequency part of the geophysical signals in time series.Among them,in terms of 40 degrees in spherical harmonics,2Bender,Polar+Bender and Bender can recover 1-day,2-days,and 3-days TVG,respectively.
Next generation gravity missionSatellite constellationClosed-loop simulation
NETL
NSTL
万方数据
