Solar Cycle Prediction and Reconstruction Using Spherical Advective Magnetic Flux Transport Codes
Speaker: David Hathaway, Computational Physics Branch, NASA Ames Research Center
Presentation
Abstract
Recent observations and analyses strongly indicate that the strength of the sun’s polar fields at the end of a sunspot cycle predicts the strength of the next sunspot cycle. The surface magnetic flux transport that builds up these polar fields is now well observed and can be realistically modeled with advective flux transport codes. Given only the emergence of magnetic flux in active regions, surface flux transport models using the observed flows can reproduce, in detail, the observed magnetic features—including both the polar fields and the large unipolar regions. These surface flux transport codes can also be used to predict the strength of the polar fields years before the end of a cycle and thus provide an earlier prediction for the strength of the next cycle. We examine the limits of these predictions by reconstructing the sun’s magnetic field in previous cycles with spherical, 2D advective flux transport codes. We find that both the surface flows and the active region sources change systematically over the course (and with the strength) of a cycle and we include those systematic variations in the model. However, stochastic variations in both the flows and the active region sources ultimately limit predictions of the solar cycle.
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 at 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.