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.
