COMPARISONS OF GRAVIMETRIC GEOID RESULTS USING MEAN GRAVITY ANOMALIES AND POTENTIAL COEFFICIENTS IN THE SOUTH AUSTRALIAN REGION

SUMMARY HY-2A is China's first satellite altimeter mission, launched in Aug. 2011. Its geodetic mission (GM) started from 2016 March 30 till present, collecting sea surface heights for about five 168-d cycles. To test how the HY-2A altimeter performs in marine gravity derivation, we use the least-squares collocation method to determine marine gravity anomalies on 1′ × 1′ grids around the South China Sea (covering 0°–30°N, 105°E–125°E) from the HY-2A/GM-measured geoid gradients. We assess the qualities of the HY-2A/GM-derived gravity over different depths and areas using the bias and tilt-adjusted ship-borne gravity anomalies from the U.S. National Centers for Environmental Information (NCEI) and the Second Institute of Oceanography, Ministry of Natural Resources (MNR) of P. R. China. The RMS difference between the HY-2A/GM-derived and the NCEI ship-borne gravity is 5.91 mGal, and is 5.33 mGal when replacing the HY-2A value from the Scripps Institution of Oceanography (SIO) V23.1 value. The RMS difference between the HY-2A/GM-derived and the MNR ship-borne gravity is 2.90 mGal, and is 2.76 mGal when replacing the HY-2A value from the SIO V23.1 value. The RMS difference between the HY-2A and SIO V23.1 value is 3.57 mGal in open sea areas at least 20 km far away from the coast. In general, the difference between the HY-2A/GM-derived gravity and ship-borne gravity decreases with decreasing gravity field roughness and increasing depth. HY-2A results in the lowest gravity accuracy in areas with islands or reefs. Our assessment result suggests that HY-2A can compete with other Ku-band altimeter missions in marine gravity derivation.

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On the topographic effects by Stokes’ formula

Journal of Geodetic Science ◽

10.2478/jogs-2014-0014 ◽

2014 ◽

Vol 4 (1) ◽

Cited By ~ 1

Author(s):

L.E. Sjöberg

Keyword(s):

Gravity Anomaly ◽

Bouguer Anomaly ◽

Gravity Anomalies ◽

Geoid Height ◽

Topographic Effects ◽

Gravimetric Geoid ◽

Bouguer Gravity ◽

The Third ◽

Stokes Formula ◽

The Difference

AbstractTraditional gravimetric geoid determination relies on Stokes’ formula with removal and restoration of the topographic effects. It is shown that this solution is in error of the order of the quasigeoid-to-geoid difference, which is mainly due to incomplete downward continuation (dwc) of gravity from the Earth’s surface to the geoid. A slightly improved estimator, based on the surface Bouguer gravity anomaly, is also biased due to the imperfect harmonic dwc the Bouguer anomaly. Only the third estimator,which uses the (harmonic) surface no-topography gravity anomaly, is consistent with the boundary condition and Stokes’ formula, providing a theoretically correct geoid height. The difference between the Bouguer and no-topography gravity anomalies (on the geoid or in space) is the “secondary indirect topographic effect”, which is a necessary correction in removing all topographic signals.

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Comparison between Altimetric and Gravimetric Geoid in the South — West Mediterranean Basin

Geodesy on the Move - International Association of Geodesy Symposia ◽

10.1007/978-3-642-72245-5_41 ◽

1998 ◽

pp. 281-287 ◽

Cited By ~ 1

Author(s):

S. Kahlouche ◽

M. I. Kariche ◽

S. A. Benahmed Daho

Keyword(s):

Mediterranean Basin ◽

Gravimetric Geoid ◽

The South ◽

South West

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Geophysical modeling of Devonian plutons in the southern Gulf of St. Lawrence: implications for Appalachian terrane boundaries in Maritime Canada

Canadian Journal of Earth Sciences ◽

10.1139/e07-038 ◽

2007 ◽

Vol 44 (11) ◽

pp. 1551-1565 ◽

Cited By ~ 1

Author(s):

Lori A Cook ◽

Sonya A Dehler ◽

Sandra M Barr

Keyword(s):

Magnetic Anomaly ◽

Prince Edward Island ◽

Sedimentary Cover ◽

Complex Structure ◽

Physical Property ◽

Gravity Anomalies ◽

The South ◽

Cape Breton Island ◽

The North ◽

Cape Breton

A prominent positive magnetic anomaly spans the 100 km distance between Prince Edward Island and Cape Breton Island in the southern Gulf of St. Lawrence. The anomaly occurs in an area of complex structure where Appalachian terrane boundaries are poorly resolved because of thick late Paleozoic sedimentary cover. Analysis of the magnetic anomaly led to the interpretation that it is produced by four separate, approximately circular, source bodies aligned along the northwesterly trend of the anomaly. Seismic data, physical property measurements, and magnetic and gravity anomalies were used to further investigate the anomaly sources through forward modeling techniques. The four source bodies have densities and magnetic susceptibilities compatible with dioritic to granitic compositions. Modeling also suggests that basement to the north of the plutons has higher density and susceptibility than basement to the south, and hence the source bodies are interpreted as plutons emplaced along the boundary between Ganderian composite terranes to the north and the Ganderian Brookville – Bras d’Or terrane to the south. This interpretation suggests that the Ganderia–Avalonia boundary is located farther south, and shows the need for re-evaluation of the location and role of the Canso fault in offsetting terranes between Cape Breton Island and southern New Brunswick.

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