Comparison of undulation difference accuracies using gravity anomalies and gravity disturbances |
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Authors: | Christopher Jekeli |
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Institution: | (1) Department of Geodetic Science, The Ohio University, 1958 Neil Ave, 43210 Columbus, Ohio |
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Abstract: | Errors are considered in the outer zone contribution to oceanic undulation differences as obtained from a set of potential
coefficients complete to degree 180. It is assumed that the gravity data of the inner zone (a spherical cap), consisting of
either gravity anomalies or gravity disturbances, has negligible error. This implies that error estimates of the total undulation
difference are analyzed. If the potential coefficients are derived from a global field of 1°×1° mean anomalies accurate to
εΔg=10 mgal, then for a cap radius of 10°, the undulation difference error (for separations between 100 km and 2000 km) ranges
from 13 cm to 55 cm in the gravity anomaly case and from 6 cm to 36 cm in the gravity disturbance case. If εΔg is reduced to 1 mgal, these errors in both cases are less than 10 cm. In the absence of a spherical cap, both cases yield
identical error estimates: about 68 cm if εΔg=1 mgal (for most separations) and ranging from 93 cm to 160 cm if εΔg=10 mgal. Introducing a perfect 30-degree reference field, the latter errors are reduced to about 110 cm for most separations. |
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