Tuesday 23 August 2005

G2

PT0025
The time-variable gravity field and the GOCE Mission
Gruber, Thomas¹, Peters, Thomas¹, Ackermann, Christian¹, Dobslaw, Hendryk²
1 Institute Of Astronomical And Physical Geodesy, Technical University Munich, Germany
2 Institute Of Planetary Geodesy, Technical University Dresden, Germany
Author email: Thomas.Gruber@bv.tu-muenchen.de
The GOCE gradiometry and high-low satellite-to-satellite tracking mission will provide observations for two measurement observation phases separated by five months. During the mission it will be decided by the project if a third measurement phase again separated by five months from the previous one will be flown. The so-called hibernation phase of five months in between the measurement phases is required due to the orbit characteristics and the power consumption requirements (long eclipse seasons). This means, that even by using GOCE data from all measurement phases we will determine a mean seasonal gravity field, if no correction is applied taking into account the seasonal gravity field variations. As a second effect the short term mass variations from the atmosphere and the oceans alias directly into the observations and could affect the quality of the resulting mean gravity field solutions significantly. For this reason, within ESA's GOCE gravity field processing system, a de-aliasing concept has been developed and is currently under implementation. This concept includes short term mass variations and as far as possible also seasonal effects taking into account results from the GRACE mission. The paper investigates the sensitivity of the GOCE mission to different sources of mass variations and provides an overview of the GOCE de-aliasing concept.

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