Study on the influence of frequency-dependent accelerometer noise in determining temporal gravity field model

On-board accelerometer is one of the key payloads for low-low satellite-to-satellite tracking mission, while its accuracy is seriously affected by the accelerometer noise level as well as the observational environment. In this study, we designed various accelerometer noise scenarios by comprehensively considering the accelerometer manufacture ability and observational environment, and further assessed the impact of frequency dependent accelerometer noise on temporal gravity field model determination. Firstly, the accelerometer noise of next generation gravity mission (NGGM) is significantly smaller than the GRACE-type accelerometer in frequency domain. However, due to the limitation of background force model errors, there is only about 2% improvement in terms of the corresponding retrieved gravity field model. Secondly, due to the periodic variations of temperature and magnetic field, there are tone errors with the integer multiples of the orbit frequency in accelerometer observations. Among the tone errors with the same type and same noise level, those in radial and along-track direction seriously affect the accuracy of temporal gravity field model, while the affect in cross-track direction is minor. If one want to obtain the sensible temporal gravity signals with reasonable north-south stripe errors, the tone errors should be limited to at least 10(-8) m . s(-2) in radial and along-track direction, while the limitation can extend to 10(-7) m . s(-2). Meanwhile, to reduce the stripe errors in spatial domain, the tone errors at high frequency should be carefully limited. Finally, the potential improvements derived from the three-axis sensitive accelerometer are discussed. However, since the minor effect of accelerometer noise in cross-track direction, the introduce of three-axis sensitive accelerometer can only improve the temporal gravity field model within 2%. Our results demonstrate that, during designing the satellite gravity mission or processing in-situ observations, we should not only consider the impact of accelerometer noise level, but also sincerely take the frequency dependent accelerometer noise into account.