The application of satellite data to potential field studies

Abstract

Satellite data can play a useful role in the compilation, reduction, and analysis of gravity and magnetic survey data, especially at regional scales. The global coverage and altitude variations afforded by satellite observations offer distinct advantages in the definition of the background terrestrial potential fields and in the analysis of related spatial anomalies. These data are also complementary to those obtained in more detailed surface and airborne surveys and can be combined in many analyses. Satellite magnetometers have been used to map the main geomagnetic field and crustal magnetic anomalies. These two signals are not completely independent, as an accurate definition of the main field is necessary for complete reduction of magnetic survey data. However, presently available mathematical models describing this field are becoming less reliable, because of the lack of recent global measurements. These measurements could be obtained, as they have been previously, through satellite observations. Although satellite data can be used to differentiate only magnetic anomalies that have wavelengths approximately 1 4 to 1 2 as long as the orbital altitude, analysis of the POGO (Polar Orbiting Geophysical Observatory) satellite data has revealed crustal anomalies of these wavelengths. Precision tracking observations of artificial satellites have been analyzed to provide information on the long-wavelength (i.e., greater than 2000 km) component of the earth's gravity field. Combining the satellite-derived gravity data with existing surface measurements provides detailed information on the terrestrial gravitational field and the undulations of the geoid relative to a reference ellipsoid. The long-wavelength gravity anomalies can provide information on the regional field through the identification of distinct broad features within the global field, information that is especially important in areas devoid of surface data. In areas where surface data are available, the two data sets can be used to produce detailed regional anomaly maps.