http:sidc'benemo

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"To understand is to perceive patterns"
http//sidc.be/nemo
ROB
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EIT Wave Detector

• Motivation
• EIT waves quantitative properties
• Free propagation
• Interaction with ARs
• Properties - Models
• NEMO software
• Architecture
• Recognition Diagnostic,
• Catalogue
• 
  in real time

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Solar Eruptions in Real time

• Flares
• CMEs

• SEC events at NOAA, SXI
• SolarSoft events
• B2Xflare

• Gopalswamy list
• http/sidc.be/cactus

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Importance of On-Disk Eruptions
geoeffectivity
SOHO profits continuous view of the Sun.
SOHO is in the L1 Lagrange point in the
Solar-Terrestrial System, and goes around the
Sun simultaneously with the Earth.
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2.36 R
FOV 45 arcmin
FOV 54 arcmin
1.67 R
Typically (CME watch) Cadence 12 min Central
wavelength 19.5 nm
Cadence 1 min Central wavelength 17.5 nm
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Space Missions STEREO

• SECCHI Sun-Earth Connection Coronal and
  Heliospheric Investigation
• Solar and heliospheric imager suite
• Instrument goal
• 3-dimensional reconstruction
• Tracking of CMEs from the Sun to the Earth
• Partners NRL (PI), NASA Lockheed (USA), MPI
  (D), CSL (B), RAL (UK), ROB (B)
• Belgian participation
• CSL hardware testing (stray light) for the
  Heliospheric Imager
• ROB software (image processing, event detection)
  and data analysis

http//stereo.nrl.navy.mil/
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How does Eruption look like in EUV?
precursor

• EIT wave

Original Image
Image substructed from prevrious one
Discovery Thompson et al, 1998 On disk
CME signatures Biesecker Thompson, 2002
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To extract such a signal from noise

• Requires an advanced  technological approach  
                       
•    
• Huge phenomenological diversity of events
• Signal weakness on top of dynamical backgrounds
• Requires a new pattern recognition approach
• methods for tracking solid objects do not apply,
• regular properties of EIT waves classification
  -gt to develop specifically tailored method.

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NEMO version 5.00 in MATLAB 7

• DETECTION of event occurrence

• Higher order moments technique (applied to EUV
  image pixels distribution)
• method to detect coherent large scale
  structure in white noise

• DIMMING extraction from EUV image

• Progressive Growth of intensive dimming region

• EIT WAVE extraction from EUV image

• Ring Analysis (for automatic calculation of
  radial velocity of the EIT wave)

• Angular-Ring Analysis (to quantify the angular
  rotation of EIT wave )

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PROGRESSIVE BUILD-UP OF DIMMINGS
a). The deep core of the dimmings together with
noise b). The basis from which we build up the
rest of the dimmings c). All regions of negative
intensity d). Selected region of negative
intensity, corresponding to the full size of the
dimmings
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Dimmings Spatial properties

• 1. Dimmings are extracted rigorously, defined
• Their area
• Integral and differential intensity structure

• Assumption dimming simply connected propagating
  region. Filtering out of noise deforming the
  dimming.
• Region of dimming propagation is determined by
  building up of filtered section of intensive
  dimming.
• Building up is done by the adding to the deep
  cut the pixels that belong to the cut on the
  intensity level of std. dev. That keep the
  condition of simple connected region.
• final dimmings

EIT wave 12/05/97
N
N
E
W
E
W
0450 UT
0507 UT
S
S
N
N
E
W
W
E
0541 UT
0524 UT
S
S
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Algorithms based on the principles
FRONT EXTRACTION
Basic principles
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Angular-Ring Analysis

• Ring Analysis

FRONT EXTRACTION
Extraction techniques
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Extracted Front Evolution EIT Wave 12 May
1997(1/4)
FRONT EXTRACTION
Example 1 (1/4) simple magnetic structure, free
front propagation
Ring analysis
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Angular 3D Structure of EIT waveEIT Wave 12 May
1997 (3/4)
FRONT EXTRACTION
Example 1 (3/4) simple magnetic structure, free
front propagation
EC
front
dimmings
Angular-Ring Analysis
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Dimmings and EIT front Integral Intensities EIT
Wave 1 April 1997
FRONT EXTRACTION
Example 4 (2/2) complex magnetic structure,
restricted front propagation
-Integral intensity of propagating front grows
in time (30 mn) symmetrically ,,,with respect
decrease of integral dimming intensity regular
peculiarity.
Angular-Ring Analysis
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Extraction
EIT Wave 12 May 1997
Space weather applications

• Real-time halo CME alerts
• Source identification
• Faint undetected halos

Integral intensity on concentric circles around
flaring center at 4 successive times
Tool for science investigation

• First systematic event catalog
• Coronal seismology

• Physical nature of
• waves fast/slow MHD?
• dimmings

• field opening, transient coronal hole ?
• Difficulties phenomenological diversity weak
  and faint events

• Observed properties
• Width of the wavefront grows quasi quadratically
  in time
• Dimming boundary contiguous to inner wavefront
  edge
• Correlation of wave structure with associated
  dimming
• Energy supply to EIT wave fronts comes from
  dimmings

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2. Geometrical Extraction (1/3)

• Solar demisphere projected on the plane
• during an EIT wave event

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Example 1 simple magnetic structure, free front
propagation
FRONT EXTRACTION
Angular 3D Structure of EIT wave
Angular-Ring Analysis
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RELATION BETWEEN EIT WAVE FRONT DIMMING
NONCIRCULAR PROPAGATION OF EIT WAVE 07/04/97
1453 - 1400 UT
1412 - 1400 -UT
1412 - 1400 -UT
NW
W
E
W
E
d3
d2
d1
d4
S
S
1435 - 1400 UT
1421-14.00 UT
1421-14.00 UT
SE
W
E
W
E
S
S
Integral intensity of each half circle in time
ANISATROPIC EIT wave structures
Dimmings
Velocity of structure propagation is different in
SE and NW. Dimmings adjoins fronts in each
directions.
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07 April 1997
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• Phase velocities of linear waves, absence of
  slow mode at ? p / 2.

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3. Validation (1/2)

• Density profile after cylindrical source
  explosion (Sedov like solution)

Spatial coordinate
time
Fast mode moving upwards and slow downwards
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A. Detection
1.
2.
3.
4.
ERUPTION MEASURE
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DETECTION method
Higher-order Moments

• Centered moment of order k

• experimental

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3. Validation (2/2)
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Example of Daily List
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Architecture
NEMO 5.0 Matlab 7.0
SOHO-STEREO-SWAP (onboard)
Detection
Geometrical Extraction
Real Time Catalog
Validation
SOHO scan catalog
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Conclusion (1/2)

• SIDC new product (sidc.be/nemo)
• Real-time catalog
• Monthly scan
• STEREO Waves

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Conclusion (2/2)

• detects only eruptions, not flares.
• can build on-disk SP.W. event catalog with SWAP
  and SECCHI.
• extraction technique brings new insight on
  events.
• is able to sort out the SOL.O. SDO dataflow
  TB/day.
• Onboard realisation (CORONAS-F)

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Thanks

• To Barbara Thompson for 1997-1998 EIT wave
  catalog
• To SIDC preview web, Cactus, B2X team
• To ESA, NASA, SECCHI/STEREO/NRL
• Orleans- LPCE, Meudon Obsrevatory, Florence
  University (European network)

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