Transcript HMIHill.ppt
Some Thoughts on HMI Data
Products & Processing
F. Hill
Jan. 27, 2005
A personal view
Developed over last 2 days during
sessions, lunches, chats, etc.
Synthesis of conversations with several
attendees.
NSO/GONG has experience in several
areas of helioseismology but they will not
be evenly covered here.
Will mainly focus on rings, but not
exclusively.
Just about every helioseismic
processing step needs work!
Magnetic effects on spectral
line characteristics
Vary with ρ?
Recent work of de Forest
Rings, peaks, ridges, etc.
V & I?
Leaks
Background & asymmetry
Inversions
Large set of choices, all bad
Adaptive strategy?
Abandon altogether?
Interpolation
Fitting
Remapping, projections,
tracking
Shape changes
Phase changes
Travel times
Non-simultaneous λ sampling
Which for rings? 1D, 2D, 3D,
RLS, OLA?
Better error estimates –
correlated
Depth-dependent trade-off
parameter
Display
Q(x,y,z,t)
VRML
Where’s the new science?
HMI is first helioseismology + vector
magnetograph combination.
Subsurface flows and magnetic field
geometry unexplored.
GONG + SOLIS provide good test bed.
Want continual synoptic flow maps and
vector B maps
More new science
HMI resolution will allow study of subsurface
flows closer to poles than before.
New highly-detailed flow maps will challenge
AFD & dynamo theory.
Ultimate goals of activity prediction and nowcasting.
Want on-demand custom tracking origin and
extent.
VSO integration will leverage SDO return.
An idea from the half-bakery
Create the “Best” flow map by combining results
from different techniques (global, rings, TD,
holography).
Construct a “point spread function” proxy (PSFP)
for each analysis.
PSFP is function of x, y, z, t, Δx, Δy, Δz, Δt.
“Deconvolve” PSFP from data – it’s the same sun.
Blind deconvolution assumes no a-priori
knowledge.
Average results with some weights.
Develop using rings
Same analysis method, but different
horizontal resolution as function of depth.
Use 3-D resolution kernels as first guess
to PSFP.
Specter of mode beating may rise again
for small-area short-time span patches.
Need resolution kernels as standard data
product.
Another semi-pastry
Return of full raw data enables 4-D power
spectra of solar atmosphere.
λ is a proxy for height in the atmosphere.
P(kx,ky,kz,ω) allows estimate of slowness
surface, useful for MHD mode studies.
Major challenges:
Calibration from λ to z (RT)
Only 5 or 6 z points (limits accuracy)
Non-simultaneous sampling in λ (Fourier shift
theorem)
Needed data products
Synoptic maps of subsurface flow
Quick-look available 24 hours after acquisition
Updated daily
sf (surface focusing) and ar (active region)
products are OK as specified
Synoptic maps of B with identical
specifications
Resolution kernels
Tentative Co-I Plans
Systematic projection comparison for rings
Attempt to combine rings with different
resolutions
Extend study of magnetic field effects on
observables
Improve fitting and inversions
Rasmus’ goal