Impact of Limitations in Geophysical Background Models on Follow-on Gravity Missions |
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Authors: | Ernst J O Schrama |
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Institution: | (1) Faculty of Aerospace Engineering, Astrodynamics and Satellite Systems, Delft University of Technology, The Netherlands |
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Abstract: | Purpose of this article is to demonstrate the effect of background geophysical corrections on a follow-on gravity mission.
We investigate the quality of two effects, tides and atmospheric pressure variations, which both act as a surface load on
the lithosphere. In both cases direct gravitational attraction of the mass variations and the secondary potential caused by
the deformation of the lithosphere are sensed by a gravity mission. In order to assess the current situation we have simulated
GRACE range-rate errors which are caused by differences in present day tide and atmospheric pressure correction models. Both
geophysical correction models are capable of generating range-rate errors up to 10 μm/s and affect the quality of the recovered temporal and static gravity fields. Unlike missions such as TOPEX/Poseidon where
tides can be estimated with the altimeter, current gravity missions are only to some degree capable of resolving these (geo)physical
limitations. One of the reasons is the use of high inclination low earth orbits without a repeating ground track strategy.
The consequence is that we will face a contamination of the gravity solution, both in the static and the time variable part.
In the conclusions of this paper we provide suggestions for improving this situation, in particular in view of follow-on gravity
missions after GRACE and GOCE, which claim an improved capability of estimating temporal variations in the Earth’s gravity
field. |
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