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Proposal ID DeForest_72

Date of Proposal
97/02/11

firstname
Craig

lastname
DeForest

institute
Stanford University

address
NASA/GSFC Code 682.3
Greenbelt, MD 20771

email
zowie@urania.nascom.nasa.gov

phone
(301)-286-3251

fax

proposal
Please note: this is an old proposal that appears to have been
rejected and slipped through the cracks- Jeff Newmark

With the recent profusion of theoretical mechanisms for coupling
sound waves and alfven waves, there is a need to search for
ways in which coherent low-frequency (3 - 5 minute period) wave
structures may leak from the photosphere into the corona, through
the transition region (which reflects most low-frequency compressive
modes).

Such waves would manifest themselves in the first three moments
of spectral line profiles in the corona: as intensity variations
(in the case of compressive wave modes); as wavelength shifts
(for transverse modes); and as line broadenings (for compressive
and torsional wave modes). All of these perturbations should be
in a fixed phase relation to the propagating waves. Of these
effects, EIT is capable of sensing only one: intensity variations
in the lines of interest. However, that is the most interesting
effect, as compressive modes are the most likely to accelerate
and heat the lower coronal plasma.

MDI's one-minute cadence observations of the photosphere provide
aa high S/N phase reference for these hypothesized waves, which
allows the use of lock-in techniques to search for traces of the
photospheric perturbation higher up. Polar plumes are near-ideal
structures for this type of study, as they are geometrically simple
compared to loops, streamers, or active regions.

I propose to look, initially, at the JOP-39 and JOP-52 high-
cadence EIT data to look for retarded correlations with the MDI
signal inside polar plumes in EIT images. If the initial analysis
proves interesting, I will search through the data archives for
other periods of high cadence EIT observations during MDI
full-disk dopplergram times, and perform similar correlation
studies on them.

Similar cross-correlation analyses are being performed between
MDI data and CDS, UVCS, and SUMER observations.

inside_collab
Barbara Thompson and/or Joseph Gurman

consortium
no

topic
Waves

topic

title
Search for Photosphere-Driven Waves in the Lower Corona


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