This page and the pages for each of the objectives
still under construction.
SOI-MDI Science Objectives and Results
The following is the list of science objectives detailed at the beginning
of the SOI program in 1987.
The primary objective of the SOI investigation is to investigate the
solar interior using the tools of helioseismology. To fulfill the potential
of helioseismology, observations free of the distortions from the Earth's
atmosphere and free of diurnal data gaps must be obtained. The primary data
set consists of precision measurements of the line-of-sight surface velocity
field from which the oscillation modes of the solar interior can be deduced.
In addition to the primary objectives, the SOI program includes investigation
of several associated science objectives. They are called associated objectives
because they involve the study of observable solar phenomena using traditional
techniques, though they share the same goal of understanding the structure
and variability of the Sun. These investigations are no less important to
the understanding of the solar structure and dynamics than the primary objectives.
Primary Science Objectives and Results
Radial Stratification
Determine the spherically symmetric components of the mean radial structure
of the Sun in and below the convective envelope of pressure, density, composition,
and sound speed.
Internal Rotation
Determine the rotation rate as a function of radius and latitude.
Large-Scale Convection
Large-scale convection cells and associated thermal structures.
Large-Scale Asphericity
Determine the non-spherically symmetric components of the mean structure
in the convective envelope of pressure, density, composition, and sound speed.
Chromospheric Structure
Analyze magnetic and thermal structures within the chromospheric acoustic
cavity.
Excitation and Damping
Explore the coupling of acoustic-gravity waves to turbulent convection.
Determine mode lifetimes, and elucidate the driving mechanisms.
Active Region Seismology
Measure the scattering and absorption of waves by active regions; search
for wakes behind sunspots; search for pre-eruptive magnetic fields.
Internal Global Scale Magnetic Fields
Determine the strength of the
toroidal magnetic fields at the base of the convection zone, and of the core
fields.
Seismic Response to Flares
Search for and analyze wave excitation by major flares.
Associated Science Objectives and Results
Large-Scale Surface Flows
Global surface flows: meridional circulation and giant cells; temperature
field associated with flows.
Magnetic Fields
Magnetograms, for validation of velocity data and support of other SOHO
experiments.
Turbulent Convection
Study granulation and mesogranulation, evolution and advection of smallest-scale
intensity features; study physics of intense turbulence.
Magneto-hydrodynamics
Study MHD processes by simultaneous sampling of velocities, temperatures,
and magnetic fields.
Supergranulation
Study evolution of supergranule convection cells and magnetic network
reorganization.
Figure of the Limb
Study long-term variations in the
figure of the limb.
Flux Budget
Spot and plage contribution to radiant flux.
Results for New Topics
Local Helioseismology
The science studying wave
oscillations in the Sun.
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Page last revised July 1, 2003