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. Developed over last 2 days during sessions, lunches, chats, etc. Synthesis of conversations with several attendees. Synthesis of conversations with several attendees. NSO/GONG has experience in several areas of helioseismology but they will not be evenly covered here. 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. Will mainly focus on rings, but not exclusively.

Just about every helioseismic processing step needs work! Magnetic effects on spectral line characteristics Magnetic effects on spectral line characteristics Shape changes Shape changes Phase changes Phase changes Travel times Travel times Non-simultaneous λ sampling Non-simultaneous λ sampling Remapping, projections, tracking Remapping, projections, tracking Large set of choices, all bad Large set of choices, all bad Adaptive strategy? Adaptive strategy? Abandon altogether? Abandon altogether? Interpolation Interpolation Vary with ρ? Vary with ρ? Recent work of de Forest Recent work of de Forest Fitting Fitting Rings, peaks, ridges, etc. V & I? Leaks Background & asymmetry Inversions Inversions Which for rings? 1D, 2D, 3D, RLS, OLA? Better error estimates – correlated Depth-dependent trade-off parameter Display Display Q(x,y,z,t) VRML

Where’s the new science? HMI is first helioseismology + vector magnetograph combination. HMI is first helioseismology + vector magnetograph combination. Subsurface flows and magnetic field geometry unexplored. Subsurface flows and magnetic field geometry unexplored. GONG + SOLIS provide good test bed. GONG + SOLIS provide good test bed. Want continual synoptic flow maps and vector B maps 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. HMI resolution will allow study of subsurface flows closer to poles than before. New highly-detailed flow maps will challenge AFD & dynamo theory. New highly-detailed flow maps will challenge AFD & dynamo theory. Ultimate goals of activity prediction and now- casting. Ultimate goals of activity prediction and now- casting. Want on-demand custom tracking origin and extent. Want on-demand custom tracking origin and extent. VSO integration will leverage SDO return. 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). 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. Construct a “point spread function” proxy (PSFP) for each analysis. PSFP is function of x, y, z, t, Δx, Δy, Δz, Δt. PSFP is function of x, y, z, t, Δx, Δy, Δz, Δt. “Deconvolve” PSFP from data – it’s the same sun. “Deconvolve” PSFP from data – it’s the same sun. Blind deconvolution assumes no a-priori knowledge. Blind deconvolution assumes no a-priori knowledge. Average results with some weights. Average results with some weights.

Develop using rings Same analysis method, but different horizontal resolution as function of depth. Same analysis method, but different horizontal resolution as function of depth. Use 3-D resolution kernels as first guess to PSFP. Use 3-D resolution kernels as first guess to PSFP. Specter of mode beating may rise again for small-area short-time span patches. Specter of mode beating may rise again for small-area short-time span patches. Need resolution kernels as standard data product. Need resolution kernels as standard data product.

Another semi-pastry Return of full raw data enables 4-D power spectra of solar atmosphere. Return of full raw data enables 4-D power spectra of solar atmosphere. λ is a proxy for height in the atmosphere. λ is a proxy for height in the atmosphere. P(k x,k y,k z,ω) allows estimate of slowness surface, useful for MHD mode studies. P(k x,k y,k z,ω) allows estimate of slowness surface, useful for MHD mode studies. Major challenges: Major challenges: Calibration from λ to z (RT) Calibration from λ to z (RT) Only 5 or 6 z points (limits accuracy) Only 5 or 6 z points (limits accuracy) Non-simultaneous sampling in λ (Fourier shift theorem) Non-simultaneous sampling in λ (Fourier shift theorem)

Needed data products Synoptic maps of subsurface flow Synoptic maps of subsurface flow Quick-look available 24 hours after acquisition Quick-look available 24 hours after acquisition Updated daily Updated daily sf (surface focusing) and ar (active region) products are OK as specified sf (surface focusing) and ar (active region) products are OK as specified Synoptic maps of B with identical specifications Synoptic maps of B with identical specifications Resolution kernels Resolution kernels

Tentative Co-I Plans Systematic projection comparison for rings Systematic projection comparison for rings Attempt to combine rings with different resolutions Attempt to combine rings with different resolutions Extend study of magnetic field effects on observables Extend study of magnetic field effects on observables Improve fitting and inversions Improve fitting and inversions

Rasmus’ goal