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Measuring and Modeling the Transport of Magnetic Flux at the Surface of the Sun – Toward Solving One-Half of the Solar Dynamo Problem

AMS Seminar Series

Speaker: David Hathaway, NASA Advanced Supercomputing Division, NASA Ames Research Center

Presentation

Seminar Slide Deck (PDF-20MB)

Abstract

Models for the transport of magnetic flux at the Sun’s surface are key to understanding the solar dynamo that produces the sunspot cycle. Observations and previous modeling have both shown that this is a purely advective process in which the magnetic field is concentrated in vertical bundles that are advected like passive scalars. This transport is facilitated by the axisymmetric flows (differential rotation and meridional flow) and by the non-axisymmetric cellular flows (granules, supergranules, and giant cells). Previous models of magnetic flux transport parameterized the non-axisymmetric components as a diffusive process and often used meridional flow profiles that were poorly constrained by observations. In this talk I will describe efforts to fully characterize all flows involved and to model the magnetic flux transport using these flows.

Biography

Hathaway received a B.S. in Astronomy in 1973 from the University of Massachusetts in Amherst, an M.S. in Physics in 1975 and a Ph.D. in Astrophysics in 1979 - both from the University of Colorado in Boulder. He was a Postdoctoral Fellow in the Advanced Study Program at the National Center for Atmospheric Research in Boulder from 1979 to 1981 and then moved to Sunspot, New Mexico where he was an Assistant Astronomer at the National Solar Observatory. In 1984 he moved to Huntsville, Alabama where he was an Astrophysicist at NASA's Marshall Space Flight Center and served as Chief of the Solar Physics Branch from 1996 to 2010. In July of 2014 he moved west to NASA’s Ames Research Center in Moffett Field, California where he continues has work as an Astrophysicist. His research interests include observing and modeling the sunspot cycle and the magnetohydrodynamics of the solar interior. He has written over 150 papers and has three US patents including two for VISAR - NASA's 2002 Invention of the year.