Browse ORBilu by Open Access
- What it is and what it isn't
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- How can I support the OA movement?
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ORBilu is a project developed by
   Seasonal Motion in the Annapolis, Maryland GPS Monument; van Dam, Tonie  ; in GPS Solutions (1999), 2(3), 41-49 The permanent GPS tracking site at Annapolis, MD shows a 7-mm seasonal signal primarily in its horizontal position. It is suggested that thermal expansion of the pier on which the antenna rests is the ... [more ▼] The permanent GPS tracking site at Annapolis, MD shows a 7-mm seasonal signal primarily in its horizontal position. It is suggested that thermal expansion of the pier on which the antenna rests is the source of this motion. A simple numerical model of the pier reproduces the observed motion of the GPS antenna, lending credence to this hypothesis. Although adding an additional level of complexity, this motion is predictable and the site retains it s value for high precision monitoring. Although the arrangement of this GPS site it somewhat uncommon, these results emphasize the importance of the underlying antenna monumentation when measuring crustal motions. [less ▲] Detailed reference viewed: 122 (1 UL)A detailed analysis of tropospheric effects on geodetic observations at TMGO; van Dam, Tonie ; et alin Physics and Chemistry of the Earth (1998), 23(1), 103-106 Improvements in geodetic tools are making previously subtle effects significant. Two examples affecting GPS observations are atmospheric loading of the Earth's crust and the tropospheric delays ... [more ▼] Improvements in geodetic tools are making previously subtle effects significant. Two examples affecting GPS observations are atmospheric loading of the Earth's crust and the tropospheric delays, specifically the wet component. Each measurement, tropospheric delays and site coordinates, requires unambiguous determination of the other to achieve the highest accuracy. Table Mountain Geophysical Observatory (TMGO) is a unique site where a long history of observations from two complementary techniques, GPS and superconducting gravimetry, have been accrued. In particular, the superconducting gravity measurements provide a unique baseline for evaluating GPS vertical estimates over a variety of time frames. Positional estimates for TMGO using these techniques will be compared. Tropospheric effects will be identified and discussed. The ability for GPS to make subdaily, daily, and long term vertical estimates will be evaluated. [less ▲] Detailed reference viewed: 127 (1 UL)Chesapeake Bay subsidence monitored as wetlands loss continues; van Dam, Tonie ; in EOS (1998), 79 Detailed reference viewed: 106 (3 UL)Sea-level rise studied in Chesapeake Bay as wetlands loss continues; ; van Dam, Tonie in Earth in Space (1998), 10(12), 156-157 Detailed reference viewed: 42 (0 UL) |
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