The behavior of a lithospheric magnetization and magnetic field model

Abstract

The Earth’s “lithosphere” is its outer shell, made up of the Earth’s crust and outermost mantle. The part of the Earth’s magnetic field that originates in the lithosphere consists of a superposition of magnetic anomalies with a broad spectrum of sizes and intensities, which arise from geological and tectonic features. The lithospheric magnetic field is known from surface observations, and on larger scales from above-surface measurements. The increase in recent decades of satellites dedicated to measuring the Earth’s magnetic field has improved significantly our models of the Earth’s magnetic environment. Based on these increasing observations, a number of comprehensive field models have been constructed, some of which focus solely on the lithosphere, such as the MF model series. We present a map of lithospheric magnetic anomalies at 400 km altitude, based on a vertically integrated magnetization model. This height was chosen because it is the expected orbital altitude of the Macau Science Satellite-1 (MSS-1) mission. The model presented herein indicates that the amplitude of the lithospheric anomalies at 400 km altitude is between −14.8 nT and 18.2 nT. This information is useful because it provides a reference for the lithospheric source of the Earth’s magnetic field that contributes to the magnetic measurements made from satellite instruments. The low inclination orbit of the MSS-1 mission will provide information that is sensitive to lateral variation within the lithosphere; these variations arise from plate tectonic features with longitudinal extent. In conclusion, the new MSS-1 mission will provide valuable information in detecting compositional variations in the lithosphere, and in delineating large-scale geological structures.

Keywords

• vertically integrated magnetization
• lithospheric magnetic field
• field model
• mss-1