67 gcc nega2ve anomalies blue occur in areas of lower

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Unformatted text preview: rages that exclude December 2004. GRACE (free air) vs. Surface (Bouguer) Correc2ons to gravity measurements •  •  •  •  Drib Correc2on Eötvös Correc2on La2tude Correc2on Topographic Correc2ons –  Free air –  Bouguer –  Terrain •  Tidal correc2ons for micro- Gal precision Regional- residual separa2on A somewhat arbitrary process designed to separate anomalies on the basis of spa2al scale, and hopefully depth. Regional- residual separa2on 3- D example from LA Basin Texas: Bouguer Anomaly Map •  •  •  •  The colors on this Bouguer gravity anomaly map represent gravity varia2ons resul2ng from lateral density varia2ons in the Earth. Posi2ve (red) anomalies represent average density greater than the Bouguer reduc2on density of 2.67 g/cc Nega2ve anomalies (blue) occur in areas of lower density. hip://pubs.usgs.gov/ds/ 2006/232/texas_boug.htm •  •  •  The Bouguer gravity anomaly grid was generated from over 76,000 gravity sta2on measurements in and adjacent to the state of Texas. Observed gravity measurements rela2ve to the IGSN- 71 datum were reduced to the Bouguer anomaly using a reduc2on density of 2.67 g/cc. Terrain correc2ons were calculated radially outward from each sta2on to a distance of 167 km. Ocean Gravity Derived from SST Merged with Land Gravity hip://...
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