A discussion of the general problem of inferring fluid velocities in the core from magnetic data. Previous results are compared with one another, and the earlier analysis is extended by allowing for small contributions to secular change from magnetic diffusion, while constraining the velocity to satisfy a quasi-geostrophic condition. The latter condition is derived from first principles, and allows for electromagnetic forces in addition to the Coriolis force. The under-determined system of equations is solved by applying a variational principle which sets up the condition that nonsingular solutions correspond to a given magnetic Reynolds number. Solutions are shown for several values of the Reynolds number and for the first time include estimates of surface electrical-current patterns. 55 pp. Refs. (KB)
This report is part of the RAND Corporation Research memorandum series. The Research Memorandum was a product of the RAND Corporation from 1948 to 1973 that represented working papers meant to report current results of RAND research to appropriate audiences.
Our mission to help improve policy and decisionmaking through research and analysis is enabled through our core values of quality and objectivity and our unwavering commitment to the highest level of integrity and ethical behavior. To help ensure our research and analysis are rigorous, objective, and nonpartisan, we subject our research publications to a robust and exacting quality-assurance process; avoid both the appearance and reality of financial and other conflicts of interest through staff training, project screening, and a policy of mandatory disclosure; and pursue transparency in our research engagements through our commitment to the open publication of our research findings and recommendations, disclosure of the source of funding of published research, and policies to ensure intellectual independence. For more information, visit www.rand.org/about/research-integrity.
The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.