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sidc.be/nemo

"To understand is to perceive patterns". http://sidc.be/nemo. ROB. EIT Wave Detector. Motivation EIT waves quantitative properties Free propagation Interaction with ARs Properties - Models NEMO software Architecture Recognition & Diagnostic,

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sidc.be/nemo

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  1. "To understand is to perceive patterns" http://sidc.be/nemo ROB

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

  3. Solar Eruptions in Real time • Flares • CMEs • SEC events at NOAA, SXI • SolarSoft events • B2Xflare • “Gopalswamy” list • http:/sidc.be/cactus

  4. 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.

  5. 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

  6. 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/

  7. 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

  8. 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 -> to develop specifically tailored method.

  9. 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 dimmingregion • 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)

  10. 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

  11. 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 04:50 UT 05:07 UT S S N N E W W E 05:41 UT 05:24 UT S S

  12. FRONT EXTRACTION • EIT wave quantities will depend explicitly on: • Distance from eruption center,i.e. length of r (defined on sphere) • Direction of radius-vectorj • Special polar • coordinate system: • Center: eruption center. • Radius vector on sphere. 1st step: Definition of eruption center (most intensive area) A posteriori: All complex EIT waves found to be well described in polar coordinates Algorithms based on the principles: Basic principles

  13. Ring Analysis Eruption Center m m into pixel into line • Ring integral intensity • Synhronous propagation of the peak in sectors FRONT EXTRACTION Angular-Ring Analysis Extraction techniques

  14. Example 1: (1/4) simple magnetic structure, free front propagation FRONT EXTRACTION • Peak propagation used for automatic definition of radial velocity Extracted Front Evolution EIT Wave 12 May 1997(1/4) Ring analysis

  15. Angular 3D Structure of EIT waveEIT Wave 12 May 1997 (3/4) FRONT EXTRACTION Hot loop overlap • Rotation • of fronts ! • Morphological similarities between fronts and dimmings! Example 1: (3/4) simple magnetic structure, free front propagation EC front dimmings Angular-Ring Analysis

  16. FRONT EXTRACTION Integral front intensity Integral dimming intensity Dimmings and EIT front Integral IntensitiesEIT Wave 1 April 1997 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

  17. 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

  18. CROSS-SECTION • 8 vertical cross-section from EC, radially Eruption center EIT wave front dimmings 2. Geometrical Extraction (1/3) • Solar demisphere projected on the plane • during an EIT wave event

  19. Example 1: simple magnetic structure, free front propagation FRONT EXTRACTION • Under condition of free propagation rotation of EIT wave fronts • observed regulary. Sense of rotation is different in the two solar • hemispheres EC EC front front dimmings dimmings Angular 3D Structure of EIT wave Angular-Ring Analysis

  20. RELATION BETWEEN EIT WAVE FRONT & DIMMING NONCIRCULAR PROPAGATION OF EIT WAVE 07/04/97 14:53 - 14:00 UT 14:12 - 14:00 -UT 14:12 - 14:00 -UT NW E W E d3 W d2 d1 d4 S S 14:35 -14:00 UT 14:21-14.00 UT 14::21-14.00 UT SE E W E W 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.

  21. 07 April 1997

  22. Phase velocities of linear waves, absence of slow mode at θ = π / 2.

  23. Density profile after cylindrical source explosion (Sedov like solution) 3. Validation (1/2) Spatial coordinate time Fast mode moving upwards and slow downwards

  24. A. Detection LASCO CME 1. 1997/04/01 06:22:00 2. 1997/04/01 09:24:33 WHERE? 3. 1997/04/01 12:05:23 4. 1997/04/01 15:18:38 1. 2. 3. 4. ERUPTION MEASURE

  25. Higher-orderMoments DETECTION: method PDF(xi) • theoretical: • Measure of PDF • asymmetry: • flatness: • g1,g2>> 0computed for pixels distribution of EUV image could be indicators of large scale coherent structures: Gaussian: g1=g2=0 for a Gaussian distribution g1=g2= 0 g1=0, g2>0 - Skewness - Kurtosis g1>0, g2>0 • Centered moment of order k: • experimental:

  26. 3. Validation (2/2)

  27. Example of Daily List

  28. Architecture NEMO 5.0 Matlab 7.0 SOHO-STEREO-SWAP (onboard) Detection Geometrical Extraction Real Time Catalog Validation SOHO scan catalog

  29. Conclusion (1/2) • SIDC new product (sidc.be/nemo) • Real-time catalog • Monthly scan • STEREO Waves

  30. 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)

  31. 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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