Plan for Pipeline Ring Diagram Analysis
R. S. Bogart, D Haber, F. Hill, & J. Toomre
v. 0.1 94.07.25
1. When:
During Dynamics time or any time essentially continuous full-disc
and/or high-res velocity and/or intensity (line depth?) images are
available for minimum of 3 days.
2. Data:
Extract subimages of each calibrated observable mapped into azimuthal
equidistant coordinates with fixed position angle centered on a set of
selection points. The mapped subimages for the full-disc field should
have an extent of 40 degrees, i.e. extend at least 20 degrees from the
selection center in all directions. The subimages on the hig-res field
will be smaller. The subimages will track in Eulerian coordinates
moving at a constant but arbitrary rotation rate applicable to the
latitude of the selection center and referred to the heliographic
coordinates of the extracted subimage at a fixed epoch.
The selection centers will be located at approximately 15 degree
spacings extending as far as +/-60 degrees latitude (closer for the
high-res field). Whether the selection centers will be selected so
that they are at the same heliographic longitude or the same
co-rotating location at their latitude is TBD, but in any case the
selection centers should be labeled by their heliographic coordinates
at central meridian passage and the time (or Carrington rotation
number) of central meridian passage. The beginning and end of data for
each tracked data array (disc crossing) is TBD; intensity may be
trackable for a longer period than velocity on full-disc images.
3. Analysis:
For each time series of tracked subimages at a given selection center,
compute the 3d spatial-temporal power spectra for time samples of 3
days' duration; if the data series is longer, multiple power spectra
are to be computed such that the whole data series is sampled. For
each power spectrum, parameters describing the location, shape, and
thickness in k_x-k_y-omega space of the rings of maximum power are
computed, probably by the method of steepest descent using initial
values which are updated from time to time as better determinations are
made of the average computed values. The ring parameters are indexed
by n and functions of omega; the tabulated parameters are the u and v
coefficients of the expansion of the perturbations of the radius of the
ring as function of azimuth; the ring radius and thickness and
amplitude.
This page last reviewed and revised 5 May 1995
Please address comments and questions to the Team Coordinator
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