Investigation of temporal gravity variations

Understanding the effect of environmental processes on gravity is a key issue for interpreting long-term gravity variations and a wide range of other geodynamic phenomena like earth tides, core motions and free oscillations of the earth as well as rotational effects. A correct modeling enables to separate disturbing gravity signals of non- instrumental origin from gravity records in order to improve the signal to noise ratio when investigating low amplitude signals. In combination with absolute gravity measurements it helps to separate local effects and makes global signals better visible. Short- and long-term atmospheric and hydrological processes play an important role in that respect. Since 1995 the superconducting gravimeter GWR C025 has been operating in Vienna. This enables now to investigate the long periodical components (Chandler wobble, long period tides) of the 7 years` gravity record. Specific short-term gravity variations as detected by GWR C025 in Vienna are another important research target. They are probably caused by vertical air redistribution occurring in atmospheric convection processes. The gravimeter is planned to be transferred to the new Conrad observatory at Trafelberg (Lower Austria) in summer 2003. This offers the possibility to investigate these gravity effects under complete different topographic conditions than at the Vienna site. A pre-processing procedure will be developed that detects these gravity effects automatically by utilizing the information of meteorological data like rain fall, air pressure and temperature in high temporal resolution. The project is performed in the framework of GGP (Global Geodynamics Project) that utilizes the results of about 25 superconducting gravimeters distributed worldwide for global geodynamics investigation.

Understanding the effect of environmental processes on gravity is a key issue for interpreting long-term gravity variations and a wide range of other geodynamic phenomena like earth tides, core motions and free oscillations of the earth as well as rotational effects. A correct modeling enables to separate disturbing gravity signals of non- instrumental origin from gravity records in order to improve the signal to noise ratio when investigating low amplitude signals. In combination with absolute gravity measurements it helps to separate local effects and makes global signals better visible. Short- and long-term atmospheric and hydrological processes play an important role in that respect. Since 1995 the superconducting gravimeter GWR C025 has been operating in Vienna. This enables now to investigate the long periodical components (Chandler wobble, long period tides) of the 7 years` gravity record. Specific short-term gravity variations as detected by GWR C025 in Vienna are another important research target. They are probably caused by vertical air redistribution occurring in atmospheric convection processes. The gravimeter is planned to be transferred to the new Conrad observatory at Trafelberg (Lower Austria) in summer 2003. This offers the possibility to investigate these gravity effects under complete different topographic conditions than at the Vienna site. A pre-processing procedure will be developed that detects these gravity effects automatically by utilizing the information of meteorological data like rain fall, air pressure and temperature in high temporal resolution. The project is performed in the framework of GGP (Global Geodynamics Project) that utilizes the results of about 25 superconducting gravimeters distributed worldwide for global geodynamics investigation.