Helioseismology of the Solar Dynamo
ROSES ID: NNH08ZDA001N Selection Year: 2009
Program Element: Focused Science Topic
Principal Investigator: Martin Woodard
Affiliation(s): Northwest Research Associates, Inc.
Wachter, Richard Co-I Stanford University
Braun, Douglas C Co-I NorthWest Research Associates, Inc.
Crouch, Ashley D Co-I NorthWest Research Associates
Schou, Jesper Co-I Max Planck Institute for Solar System Research
Birch, Aaron C Co-I Max Planck Institute for Solar System Research
We propose to improve current measurements of solar meridional and zonal flows
by analyzing the nearly continuous 12-year sequence of Dopplergrams from the
SOHO/MDI medium-l helioseismology program.
The analysis technique we will use is based on measuring a mode-leakage
matrix which is sensitive to the distortion of mode eigenfunctions by flows
Significant effort will be devoted to identifying, understanding, and
modeling instrumental error.
We are proposing (1) to model and correct for instrumental and
radiative transfer effects, (2) to model the theoretical effect of differential
rotation and meridional circulation on the leakage matrix, (3) to develop
and verify codes to fit the leakage model to helioseismic data, and to
run the fitting codes on MDI data and, (4) to invert measurements of the
leakage matrix for meridional and zonal flows.
The resulting measurements of deep flows are anticipated to be accurate
enough to impact our understanding of the solar dynamo, as meridional flow
is a critical component of flux-transport dynamos. In addition, the
leakage matrix measurements we will carry out will be useful to other
areas of helioseismology.
The goals and measures of success of Focused Science Topic (a) -- "Measure
the properties of the solar dynamo that affect solar irradiance and active
region generation" -- include "improved measurements of critical subsurface
flows, including the expected deep meridional flow." The detection of sub-
surface meridional flow promises to facilitate our understanding of, and
perhaps predict, the generation, emergence, and evolution of magnetic
regions. This research is therefore critical to the TR&T Focused Science
Topic and NASA's Strategic Subgoal 3B through Research Objective 3B.1:
"Understand the fundamental physical processes of the space environment from
the Sun to Earth .. ", which addresses NASA's Science Question, "How and why
does the Sun vary?" from Strategic Subgoal 3B.
|Performance Year||Reference||Investigation Type||Actions|
|1||Woodard, M. F.; (2009), Seismic Detection of Solar Mesogra...||not set|
|1||Woodard, M.; Schou, J.; Birch, A. C.; Larson, T. P....||not set|
|1||Woodard, M.; (2014), Detectability of Large-Scale Solar Sub...||not set|
|1||Woodard, Martin F.; (2009), Helioseismic Detection of Mesogr...|
|1||Schou, Jesper; Woodard, M. F.; Birch, A. C.; (2009), ...|
|1||Woodard, M. F.; (2009), Helioseismic Measurement of Large-Sc...|
|1||Schou, Jesper; Woodard, M. F.; Larson, T. P.; (2012),...|
Export to PDF