VUME Upper Mantle of the Earth

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Magnetic Observatory.





International Real-time Magnetic Observatory Network Map.
A large number of geomagnetic observatories throughout the world are members of INTERMAGNET. All these observatories send their data to Geomagnetic Information Nodes. In order to become an INTERMAGNET observatory (IMO) a strict set of conditions must be met. These conditions are described in the INTERMAGNET Technical Manual. Use the list of IMOS to follow the links to individual observatories. Details on location, instrumentation, type of data, etc. are given in the pages for the individual observatories.
map of IMOs in the world
The USGS National Geomagnetism Program.

The mission of the U.S. Geological Survey’s Geomagnetism Program is кeal-time monitoring the Earth’s magnetic field. Using ground-based observatories, the Program provides continuous records of magnetic field variations covering long timescales; disseminates magnetic data to various governmental, academic, and private institutions; and conducts research into the nature of geomagnetic variations for purposes of scientific understanding and hazard mitigation.
USGS data are used for research and practical application.
The USGS Geomagnetism Program’s work with foreign national geomagnetism programs is coordinated through INTERMAGNET, a worldwide consortium of observatory programs, and the International Association of Geomagnetism and Aeronomy.
Regionally, USGS data are used to support aeromagnetic surveys and directional drilling programs for the oil and gas extraction industry.
USGS data also are used by the pipeline and electrical power grid industries, as well as for academic studies across a broad range of geophysical sciences.
Observatories
The geographic distribution of Geomagnetism Program observatories. Click on the observatory name for details of each facility.
Map of U.S.G.S. magnetic observatory locations.
Map of USGS Magnetic Observatory Locations. Guam (GUA) Honolulu (HON) Fresno (FRN) Tucson (TUC) Deadhorse (DED) Stennis (BSL) San Juan (SJG) Fredericksburg (FRD) Boulder (BOU) Shumagin (SHU) Newport (NEW) Sitka (SIT) College (CMO) Barrow (BRW)
United States Geological Survey (USGS)
The United States Geological Survey (USGS) is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology, geography, geology, and hydrology. The USGS is a fact-finding research organization with no regulatory responsibility.

Observatory Sensor Package





The basic sensor package at each observatory consists of:
- A tri-axial fluxgate magnetometer which gathers vectorial data, typically the horizontal intensity, declination, and the vertical component (H,D,Z);
- A proton magnetometer, which measures the total intensity of the field (F);
- A theodolite coupled to a small magnetometer;
- The piers that are firmly anchored into the ground;
- The buildings of observatory are situated on plots of land of sufficient size to help isolate the operations from outside magnetic interference.
The redundancy between two measurement systems allows for consistency checks that are useful for troubleshooting. A fluxgate sensor-electronics package is prone to deliver data that drift on an absolute scale, primarily as the result of changes in ambient temperature; proton magnetometer data also drift with temperature, but usually much less than fluxgate data. To reduce this baseline drift, the sensors and electronics are housed in well-insulated, thermostatically-controlled buildings, but even then there remains some residual baseline drift.





Therefore, each observatory is visited by a Program employee or contractor once a week so that so-called ‘absolute’ measurements can be made using a theodolite coupled to a small magnetometer; these data are used later during data processing to make final adjustments to the data baselines. To preserve sensor orientation, both the fluxgate magnetometer and the theodolite are supported by piers that are firmly anchored into the ground. Finally, the buildings at each observatory are situated on plots of land of sufficient size to help isolate the operations from outside magnetic interference. The observatory standards are consistent with those set by Intermagnet, an international consortium which promotes the worldwide collection of high-quality, ground-based magnetometer data.