The National Geomagnetic Initiative (1993) / Chapter Skim
Currently Skimming:
Scientific Framework
Scientific Framework
Pages 11-17
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 11... ...
The Earth's lithosphere, asthenosphere, deep mantle and core, oceans, and solar-terrestrial environment either as primary sources or as induced secondary sources—contribute magnetic "signals" that must be separated and decoded to obtain an "image" of the underlying physical processes. Recent technological advances present unique opportunities for studies of the geomagnetic field to contribute to the understanding of a variety of dynamic processes in the solid Earth and geospace environment.
|
From page 12... ...
· What role does the magnetic field play in coupling the core and the mantle, contributing to changes in the length of the day over time scales of decades? · How are fluids- water phases and/or molten magma distributed in the deep crust, and what is their role in regional tectonic processes?
|
From page 13... ...
The scientific issues that can now be addressed through implementing this technology include the following: · the recovery and interpretation of low-amplitude, long- and short-wavelength magnetic anomalies from airborne, marine, and satellite surveys; · the nature of the coupling of ionospheric and magnetospheric processes; · an understanding of dynamic processes in the core as they affect global magnetic field modeling and long-term prediction of secular variations; and · regional and global electromagnetic induction phenomena, including those processes associated with the dynamics of the oceans themselves. An initiative to capitalize on the new opportunities and to address questions related to geomagnetism can be readily and cost-effectively mobilized within the traditional research establishment (federal and state agencies, academia, industry, and scientific societies)
|
From page 14... ...
, a refined assessment of natural resources and natural hazards of the continental and oceanic crust, improved and safer navigation, and more reliable satellite-based communications. The Dynamics of the Global Geomagnetic Environment Contemporary views of the Earth's magnetic field emphasize its variable nature on a wide range of scales in space and time.
|
From page 15... ...
At periods of less than a few years to a decade, contributions from internal field sources originating in the core overlap the spectrum of transient external field sources in the magnetosphere and ionosphere. These external magnetic field sources fluctuate over characteristic times ranging from a few seconds to a few years or longer and have characteristic dimensions at the Earth's surface of lot to 104 kilometers (km)
|
From page 16... ...
An upgraded global monitoring network is not only essential for correcting magnetic survey data; it would also be used to define the conductivity structure of the Earth's lithosphere and upper mantle and to study fundamental plasma processes in the magnetosphere. Ground-based
|
From page 17... ...
These facilities, which require major funding commitments and involve long lead times for implementation, have longterm value to many federal agencies and to the scientific community at large. Recommendations · A national geomagnetic initiative should be undertaken to define objectives and encourage coordination among federal and state agencies, academic institutions, and industry to systematically characterize the spatial and temporal behavior of the Earth's magnetic field on local, regional, and global scales and to apply this understanding to a variety of scientific problems and to technical and societal needs.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.