The National Geomagnetic Initiative (1993) / Chapter Skim
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Observational Needs and Facilities
Observational Needs and Facilities
Pages 51-60
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From page 51... ...
satellite measurements; and 4. prehistorical reconstructions, historical data, and laboratory measurements.
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From page 52... ...
. In the past, arrays of many tens of simultaneously recording variometers have been temporarily deployed to detect electrical conductivity anomalies in the crust and upper mantle or to record activity in the ionosphere and magnetosphere, but at present there are no arrays of high-frequency instruments available to the scientific community in the United States.
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From page 53... ...
OBSERVATIONAL NEEDS AND FACILITIES 53 FIGURE 4-1 Global distribution of magnetic observatories in operation in 1993 (courtesy NOAA-National Geophysical Data Center)
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From page 54... ...
Ocean bottom installations can be located on transoceanic communication cables that have recently become available to the scientific community. In addition to the observatory network, there is a critical need for a portable network facility to measure magnetic variations for induction studies and for studying the ionosphere and magnetosphere.
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From page 55... ...
They could be filtered or averaged to maintain their scientific usefulness while protecting the proprietary interests of the source. The needs of the scientific community will not be met by simple addon activities (for example, "ships of opportunity")
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From page 56... ...
Satellite Measurements The value of satellite measurements of the Earth's magnetic and plasma fields has been evident since the first measurements by Sputnik 3 in 1958. Subsequent pioneering missions include the Magsat mission that made a major advance in the characterization of the internal magnetic field; the Defense Meteorological Satellite Program (DMSP)
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From page 57... ...
Measurement of electric currents associated with the auroral plasma environment is a key element in characterizing the state of the magnetosphere, because Joule dissipation provides almost twice as much energy deposition into the upper atmosphere as particle precipitation does. Commerce, the military, and society increasingly rely on a network of sophisticated communication and other service satellites in geosynchronous orbit, but these systems are vulnerable to the flux of particles and fields.
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From page 58... ...
Since no single investigator or institution now supports the necessary range of analytical and experimental facilities needed for such studies, an increased level of collaboration will be required among individual investigators measuring both physical and chemical properties. In an analogous way, laboratory studies of electrical conductivity provide the means for inferring the nature of physical and chemical processes in the Earth from estimates of the conductivity from field observations.
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From page 59... ...
The installation of approximately 20 island stations and 25 oceanbottom stations would be a major step forward in developing this network in support of ongoing work to update the IGRF and for magnetospheric and solid-Earth induction studies. The community of solid-Earth and space scientists should work with the relevant government agencies to develop detailed implementation plans for the full network and to address funding and management issues.
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From page 60... ...
survey over the United States should be undertaken for baseline control and for regional charting. Data from a highaltimde survey would provide a consistent data set free from intense local anomalies derived from upper crustal rocks, which is needed for leveling and "stitching together" individual {owaltitude magnetic surveys to upgrade the magnetic anomaly map of North America.
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