1. ARCGICE WP 5.1 Leader: UCL Synthesis report on benefit of combining data C.C.Tscherning, University of Copenhagen, 2005-03-01 1

2. Observations: Parameter is equal to N 0 mean sea surface height A i = 1 if bias only for all values of i which are associated with geoid heights. Parameter and error-estimation C.C.Tscherning, University of Copenhagen, 2005-01-13 2

3. Then an estimate of T and of the parameters X are obtained as where W is the a-priori weight matrix for the parameters (Generally the zero matrix). Parameter estimate C.C.Tscherning, University of Copenhagen, 2005-01-13 3

4. The associated error estimates are with the mean square error of the parameter vector and the mean square error of an estimated quantity. Error-estimates C.C.Tscherning, University of Copenhagen, 2005-01-13 4

5. 1.From knowledge of survey type or data- collection method. 2.From comparison with independent sources such as MSS from WP 1.2 3.From comparison of two sources in same area. Spatial errors C.C.Tscherning, University of Copenhagen, 2005-01-13 5

6. Least-squares collocation with parameters may be used to combine data dependent on gravity field and a few other physical parameters. Data-combination C.C.Tscherning, University of Copenhagen, 2005-01-13 6