Thank you for your interest in SOHO EIT data analysis.

Proposal ID Worden_36

Date of Proposal



High Altitude Observatory/NCAR

PO Box 3000
Boulder, Co 80307-3000


303 497 8324

303 497 1589

I am interested in analyzing some of the EIT images. I am most interested
in analyzing the He II 304 data but would like to attempt to examine the
shorter wavelength corona data. The analysis would be to identify the plage,
decayed plage, enhanced network, and quiet sun on each image. I would then
compare these "masks" of the EIT images with similar type "masks" that I have
already derived for NSO Sacramento Peak Ca II K images. The algorithms
for this identification procedure was developed as part of my doctoral
dissertation. If interested I can send you a copy, but briefly, the algorithm
uses intensity, size, and filling factor to identify the different structures
on the solar disk. The goal of this analysis is to derive contrasts and mapping
functions of the He 304 line and hopefully of the corona lines for
use with a model of solar irradiance variability. Ideally it would be
good to have at least 10 images at each wavelength that correspond to
the Ca II K images that I have already analyzed. I can work with Don
Hassler, here at HAO, to obtain these images upon approval of this

Dr. Werner Neupert, Dr. Joe Gurman


EUV Sources


Comparison of EUV active features with Ca II K images and masks

update added on 1998/02/19 at 16:45:25
Progress Report: I have submitted paper titled "Evolution
of Chromospheric Structures: How Chromospheric Structures
Contribute to the Solar He II 30.4 nm Irradiance and Variability.
I also have submitted a poster sesseion to the AGU spring meeting.

The abstract for the paper and the session is:
Abstract. The bright He II 30.4 nm solar emission is an
important energy source for ionization and heating of the
Earths upper atmosphere. The analysis of the Solar and
Heliospheric Observatory (SOHO) Extreme-Ultraviolet
Imaging Telescope (EIT) He II 30.4 nm images provides
an improved understanding on how the solar surface
structures, i.e. plage, enhanced network, active network,
and quiet-chromosphere, contribute to the solar He II 30.4
nm irradiance. Our results can be used to derive a model of
the solar He II 30.4 nm irradiance over the solar cycle. The
plage, enhanced network, active network, and quiet-
chromosphere structures are identified on each EIT He II
image with an algorithm that uses criteria of intensity, size,
filling factor, and continuity. This decomposition leads to
time series of structure area and integrated intensity, their
spatial distribution on the solar disk, and their intensity
contrast relative to the quiet-chromosphere intensity thus,
these time series show how the solar surface structures
contribute to the He II 30.4 nm irradiance. For example,
we find that the active network contributes as much as the
plage and enhanced network to the solar He II 30.4 nm
irradiance variability during solar minimum. In addition,
although we cannot explicitly show that the quiet-
chromosphere intensity varies during solar minimum, we
can place an upper limit of 1.4% on any potential solar
minimum quiet-chromosphere intensity variations.

Please describe additions or updates to your proposal.

You must click the "submit" button in order to enter your proposal update. Thank you.

Return to the EIT home page.