Preliminary verification of dual-satellite tandem altimetry on board
The classic method to derive gravity field from satellite altimetry is first to calculate the deflection of the vertical using the sea surface height difference(SSHD),and then further to calculate the marine gravity anomaly and the marine geoid height,et al.Obviously,improving the measurement accuracy of SSHD can directly improve the inversion accuracy of ocean gravity field.The dual-satellite tandem altimetry principle is proposed in the paper.By designing the orbit of dual-satellite,the cross orbit distance(i.e.resolution)between the sub-satellite points of the dual-satellite can be reached about 1 arcmin.The dual-satellite simultaneously measure the SSHD along their orbital direction and in the cross orbital direction.At this time,the radial error of the orbit is showed as the relative orbital radial error between dual-satellite or between single satellite observation epochs,and the corrections related to atmospheric propagation and geophysical effects are approximately equal for dual-satellite with a ground orbit spacing of only 1 arcmin,and are rarely reflected in the SSHD.Therefore,the accuracy of SSHD will be significantly improved compared to that of the traditional single satellite condition.Using the actual observation data from our twin altimetry satellites A,B,the difference error between the relative orbit radial error and the eight corrections in the SSHD was preliminarily verified.The results show that for the calibration stage with a distance of about 25 km between sub-satellite points,the difference errors of corrections such as dry troposphere,wet troposphere,ionosphere,solid tide,polar tide,and reverse atmospheric pressure are all on the order of 5 mm.There are residual errors of approximately 1 cm and 2 cm in the difference in tidal correction and sea state deviation,respectively.For the sub-satellite point spacing of about 2 km in the busi-ness orbit,the relative orbital radial error is about 3 mm,and except for the residual error of about 0.52 cm in the sea state de-viation difference,the difference error of other corrections is less than 0.05 cm and can be completely ignored.
satellite altimetrydual-satellite tandem altimetry modemarine gravity fielddeflection of the verticalrelative orbit determinationsea state bias
万方数据
维普
