I: Session C3 Thermal Studies : Techniques

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I Session C3Thermal Studies Techniques

• Chair(s) Mark Weber Paul Boerner
• Status draft

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Guidelines to group leads

• Assess the task definitions in appendix A (AIA
  Science Plan) in the 2004 Concept Study Report
  (CSR). In particular
• Science/task descriptions in Ch. A1.1
• Summaries in Table A2
• Identify required changes from, and additions to,
  the AIA Science Plan
• Evaluate the status of that plan, and formulate
  changes, if needed.
• You may add as many pages to this document as you
  need, but
• Add pages under the same headings please, do not
  change the roman numerals in the page titles,
  please add a, b, c, d,
• Resources
• AIA home http//aia.lmsal.com/
• AIA CSR summary http//aia.lmsal.com/public/CSR.h
  tm
• CSR https//aia.lmsal.com/doc?cmdvcurproj_numA
  IA00435
• Proposal https//aia.lmsal.com/doc?cmdvcurproj_
  numAIA00341

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Schedule

• 17 November 2005 draft sheets I, II to teams,
  requesting input for sheets III and IV
• 24 November 2005 completed sheets I-IV for
  review to teams, requesting input for sheets V-VI
• 8 December 2005 team input received for sheets
  V-VI
• 19 December 2005 draft of sheets VII-VIII to
  teams
• 9 January 2006 team comments received for sheets
  VII-VIII
• 6 February 2006 draft Science plans on meeting
  website, with sheets IX-X filled out by team
  leads (or teams after telecons)
• 13-17 February 2006 discussions during science
  team meeting discuss and complete pages IX-X.
• 17 February completed Science plans on line.

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IIa Science questions and tasks (from CSR)

• Primary scientific questions
• Objective 2 Study coronal heating and
  irradiance, and the origins of the thermal
  structure and coronal emission, to understand the
  basic properties of the solar coronal plasma and
  field, and the spatially-resolved input to solar
  spectral irradiance.
• SDO/AIA science tasks
• Task 2B Characterize the physical properties of
  coronal structures

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IIb Science questions and tasks (DEM recovery)

• DEM recovery offers a description of the thermal
  structure along a line of sight, which allows us
  to
• distinguish overlapping structures in the
  optically-thin corona
• distinguish between plasma motion and heating
• identify the location and magnitude of heating
  and cooling events
• track plasma topology and connectivity
• relate morphology and dynamics observed in the
  corona with AIA to irradiance observed with EVE

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IIIa Science context

• There are a number of upcoming advances that
  should leave us in a better position to do
  thermal studies when SDO launches than we are
  now
• Observations with broader spectral (and thermal)
  coverage, particularly from SOLAR-B EIS and XRT
  also GOES-N SXI, STEREO SECCHI
• Gradual improvements in spectral codes and
  databases
• Faster computers and larger displays, which will
  facilitate the computation and visualization of
  DEM data products
• Improvements in the software and techniques that
  enable the analytic combination of multiple
  instrument datasets (e.g. TRACE, MDI, EIT, CDS)

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IIIb Science context (cont.)

• SDO should advance our understanding of coronal
  thermal structure even further
• AIA is designed for DEM recovery, with more EUV
  bandpasses than have ever been available from a
  high-resolution imager
• High spatial resolution is required in order to
  study the thermal properties of elemental
  structures
• High cadence allows studies of the evolution of
  coronal structures at the shortest relevant
  timescale

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IVa Science investigation

• Uncertainties in spectral models are a major
  obstacle
• databases rely on tabulated measurements of
  abundance, ionization balance, etc., which may
  not be correct or constant
• spectral databases do not have complete
  catalogues of coronal emission lines
• Another major obstacle is the scaling of the
  computation
• difficult to compute, analyze and display DEMs
  for the whole volume of AIA observations

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IVb Science investigation

• Additional obstacles
• instability of DEM inversion in the presence of
  error and uncertainty
• range of possible DEM solutions and uniqueness of
  recovered DEM must be estimated and understood
• optical depth of plasma is difficult to
  accommodate in large scale, automated codes
• going from LOS DEM to a description of thermal
  structure in a volume element not always trivial

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V Implementation general

• In order to improve our ability to do useful
  thermal studies, we need
• A DEM working group that will
• foster a broader understanding of the need for,
  and difficulty of, DEM analysis
• reach a consensus on many implementation issues
• Improvements to spectral models and databases
• These will allow us to work towards a standard
  DEM recovery code that will provide easily
  understood uncertainty estimates, temperature
  maps, and LOS discrimination

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VI Implementation AIAHMI

• DEM inversion requires AIA observations
• in all EUV bandpasses
• near-simultaneous
• Cadence of 1 minute
• Full dynamic range (longest exposures possible
  without saturating)
• Simultaneous HMI observations to enable study of
  topology/connectivity
• requires co-alignment with AIA
• Simultaneous EVE observations for
  cross-calibration

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VII AIA (HMIEVE) data products

• Critical data products
• SDO data
• AIA observations in EUV bandpasses
• Desireable data products
• SDO data
• HMI observations of magnetic field
• EVE observations for cross-calibration
• Supporting data from other observatories
• EIS spectra for cross-calibration
• STEREO images to distinguish 3-D structure

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VIIIa AIA (HMIEVE) data production

• Open question should there be a DEM data product
  in the pipeline?
• computationally intensive
• could implement linear inversion or lookup table
• numerous knobs must be set almost arbitrarily
• parameterization of DEM (range, resolution in T
  space)
• spectral code and assumptions (abundance,
  pressure, etc)
• conduct DEM recovery study to optimize these
  settings
• difficult to include other observations in the
  pipeline

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VIIIb AIA (HMIEVE) data production

• If we do have a standard DEM product, we will
  need to decide
• how comprehensively it will be produced
• full-disk, full-resolution per-pixel DEMs?
• bin pixels, sum over multiple exposures
• run DEM recovery routine selectively
• how to display the recovered DEM
• temperature maps
• error bars/level of certainty

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IXa Business plan Resources

• AIA can be used for thermal studies in 2 ways
  for quicklook T maps, and for more
  careful/detailed DEM reconstruction.
• It would be useful to supply 2 DEM data/code
  products
• A pipeline DEM/Temperature map data product
• A set of software tools to allow expert users to
  perform DEM reconstruction

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IXb Business plan Resources

• The pipeline data product should
• Be clear and usable by experts and non-experts
• Supply information that is not available in the
  standard images
• Allow users to identify features, events, and
  regions that warrant for further study
• The DEM reconstruction software package should
  allow users to
• Tweak a variety of atomic parameters (abundance,
  charge state, etc.) and a priori constraints
  (smoothness, etc.)
• Include observations from other instruments, and
  from models
• Understand the uncertainties in the recovered DEM

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Xa Business plan Implementation

• Develop a white paper and work with people who
  calculate and measure atomic physics properties
  to reduce atomic uncertainties in the AIA
  bandpasses
• Hold workshops to develop an understanding of the
  problem of DEM reconstruction with AIA
• 30 participants, incl. representatives of the
  instrument, spectral codes, and modeling teams
• Focused on DEM reconstruction problems (not
  spectral codes)
• Inversion algorithms
• Uncertainties
• Data pipeline realities
• Preliminary meeting adjacent to SPD 2006
  identify problems and have volunteers work on
  them
• Follow-up meeting in Feb 2007

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Xb Business plan Implementation

• The Pipeline Product Do we need a DEM data
  product in the pipeline? This fundamental
  question is still unanswered
• Survey community to determine how it would be
  used, and how useful it would be (May 2006)
• Based on the study of how practical DEM
  reconstruction is (see Xa), develop and test
  methods to determine how it could be implemented
  (Early-mid 2007)
• Spatial resolution (number of DEM pixels)
• Inversion technique
• Standard set of atomic physics assumptions