SESSION: C3

Thermal Studies 


TIME: Tuesday, Feb-14, 10:30--noon.


SUMMARY:

This discussion section will address a variety of topics related
to AIA science, differential emission measure (DEM) estimation, and
temperature (thermal) maps. Some time will be allocated for
participants to make brief presentations on the topics listed below,
with ample time allocated for followup discussion. An emphasis will
be given to issues which bear upon the scientific, operational, and
technical aspects of DEM analysis with AIA. The principal goals for
this discussion are (a) to generate commentary on issues of DEM
analysis for AIA science; and (b) to promote the scientific value
of DEM products in the new era of "very multi"-channel imagers.


FORMAT:

The session is 1.5 hours long, broken into four main topics (see
below).  For each topic, we welcome a few brief presentations (each
about 2 slides, 3--4 minutes) which focus on highlighting specific
issues of DEM analysis.  There will be extended time reserved for
open discussion on each topic and set of presentations. This is a
working discussion group, so participants are expected to have some
familiarity with DEM analysis.


THE HARE & HOUND CHALLENGE:

In conjunction with the discussion group, we are providing a set
of DEM puzzles for participants to work on before the meeting. The
goal is provide some mutual context for the discussion section, and
compare notes among research groups regarding techniques and issues.
Go *here* for a full description.

www.lmsal.com/~boerner/demtest/


TOPICS:

The following four main topics will be allocated time in the discussion
section. We list here possible subtopics for discussion for each main
topic. Participants are welcome to comment on these issues and/or
introduce other issues.

1. Atomic and Plasma Physics Models. DEM analysis relies on physical
models of coronal abundances, ionizations states, and atomic spectra,
which may dominate the uncertainties in DEM estimations. Key subtopics
for discussion include:

- pros and cons of current spectral codes
- abundances and ionization states
- optical depth of emitting plasma along the lines of sight
- propogation of uncertainties into DEM analysis
- modularity and interface of codes with DEM tools

2. DEM Algorithms and Techniques. Various approaches to DEM analysis
have a variety of pros and cons, and some aspects have yet to be
fully investigated and understood. Some examples of relevant subtopics
are:

- "forward search" versus direct inversion methods
- selection of solution temperature range and temperature bins
  appropriate to instrument
- a priori constraints (eg, positivity, smoothness, etc)
- estimating uncertainties due to: under-determined inversion,
  instrument calibration(s), details specific to algorithms, spectral
  codes, etc.

3. Data and IT Resources. Solving and rendering DEM data products
may require new levels of computing and display power. These issues
should be recognized and addressed. Possible subtopics for discussion
are:

- defining useful data products (eg, temperature maps)
- determining computational power required for data products and 
  solution methods
- defining useful and reasonable levels of modularity and flexibility
  for DEM tools provided by the instrument teams
- conceiving graphical methods for communicating the information
  of DEM solution/uncertainty sets across images with millions of pixels
- instrument-team provided DEM products (near real-time cadence)
  versus end-user tools (greater flexibility, processing)

4. DEM Science. New types of investigations in coronal physics will be
possible with SDO data and state-of-the-art DEM techniques.Subtopic
examples are:

- Distinguish structures along LOS.
- Catch plasma evolving through temperature bins; distinguish
  temperature changes vs plasma flows.
- Locations and magnitudes of heating and cooling.
- Topology and connectivity (and helicity?).
- Relation to EVE irradiance.