The construction of sparse models of Mars's crustal magnetic field
Abstract
Previous work has shown that Mars's crustal magnetic field is highly nonuniform, with large regions of either very weak or very strong magnetic field. Commonly used techniques of magnetic field analysis (such as truncation or L2 regularization of a spherical harmonic expansion) have a smoothing effect and are not well suited to representing magnetic fields which may have regions of zero magnetization or sharp contrasts in magnetization. Indeed, there is no a priori reason to expect that the crustal field should be smooth. In this study, we use L1 and elastic net regularizations of Mars Global Surveyor magnetometer data to create sparse representations of the magnetic field of Mars, and examine what percentage of the surface field is actually required to have nonzero magnetization in order to fit the data. We find that solutions with up to 98% or higher sparsity yield an adequate fit to the data, although solutions with 85% sparsity are more realistic. These sparse solutions are substantially different from other smoothed solutions. The choice of inversion method used to analyze the data significantly impacts the resulting field morphology, which may affect the resulting physical interpretation.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jul 01, 2017
- Source ID
- 10.1002/2016je005238
Entities
People
- Jeremy Bloxham
- Kimberly M. Moore
Organizations
- Harvard University
- United States Department of Defense