To understand is to perceive patterns http sidc
- Slides: 34
"To understand is to perceive patterns" http: //sidc. be/nemo ROB NEMO ESSW 3 SIDC
EIT Wave Detector Motivation Ø EIT waves quantitative properties m Free propagation m Interaction with ARs Properties - Models NEMO software Ø Architecture Ø Recognition & Diagnostic, Catalogue in real time NEMO ESSW 3 SIDC
Solar Eruptions in Real time Flares Ø SEC events at NOAA, SXI Ø Solar. Soft events Ø B 2 Xflare CMEs Ø “Gopalswamy” list Ø http: /sidc. be/cactus NEMO ESSW 3 SIDC
Importance of On-Disk Eruptions geoeffectivity SOHO profits continuous view of the Sun. SOHO is in the L 1 Lagrange point in the Solar-Terrestrial System, and goes around the Sun simultaneously with the Earth. NEMO ESSW 3 SIDC
2. 36 R FOV: 45 arcmin FOV: 54 arcmin 1. 67 R Typically (CME watch): Cadence: 12 min Central wavelength: 19. 5 nm NEMO Cadence: 1 min Central wavelength: 17. 5 nm ESSW 3 SIDC
Space Missions: STEREO SECCHI: Sun-Earth Connection Coronal Heliospheric Investigation and Ø Solar and heliospheric imager suite Ø Instrument goal: m 3 -dimensional reconstruction m Tracking of CMEs from the Sun to the Earth Ø Partners: NRL (PI), NASA & Lockheed (USA), MPI (D), CSL (B), RAL (UK), ROB (B) Belgian participation: Ø CSL: hardware & testing (stray light) for the Heliospheric Imager Ø ROB: software (image processing, event detection) and data analysis NEMO http: //stereo. nrl. navy. mil/ ESSW 3 SIDC
How does Eruption look like in EUV? precursor “EIT wave” Original Image substructed from prevrious one Discovery: Thompson et al, 1998; On disk CME signatures: Biesecker & Thompson, 2002 NEMO ESSW 3 SIDC
To extract such a signal from noise Requires an advanced technological approach Ø Huge phenomenological diversity of events Ø Signal weakness on top of dynamical backgrounds Requires a new pattern recognition approach Ø methods for tracking solid objects do not apply, Ø regular properties of EIT waves classification -> to develop specifically tailored method. NEMO ESSW 3 SIDC
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 ) NEMO ESSW 3 SIDC
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 NEMO ESSW 3 SIDC
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: N E W S E W 04: 50 UT S 05: 07 UT N N W E S NEMO EIT wave 12/05/97 N 05: 24 UT ESSW 3 E W S 05: 41 UT SIDC
FRONT EXTRACTION Algorithms based on the principles: EIT wave quantities will depend explicitly on: Distance from eruption center, i. e. length of r (defined on sphere) Direction of radius-vector j Special polar coordinate system: Center: eruption center. 1 st step: Radius vector on sphere. Definition of eruption center (most intensive area) A posteriori: All complex EIT waves found to be well described in polar coordinates NEMOprinciples Basic ESSW 3 SIDC
Ring Analysis Angular-Ring Analysis FRONT EXTRACTION Eruption Center m into line into pixel m Synhronous propagation of the peak in sectors NEMO Extraction techniques ESSW 3 Ring integral intensity SIDC
Example 1: (1/4) simple magnetic structure, free front propagation Extracted Front Evolution FRONT EXTRACTION EIT Wave 12 May 1997(1/4) Peak propagation used for automatic definition of radial velocity NEMO Ring analysis ESSW 3 SIDC
FRONT EXTRACTION Angular 3 D Structure of EIT wave Example 1: (3/4) simple magnetic structure, free front propagation EIT Wave 12 May 1997 (3/4) EC front dimmings Hot loop overlap Rotation of fronts Angular-Ring Analysis NEMO Morphological similarities ESSW 3 between fronts and ! SIDC
FRONT EXTRACTION Dimmings and EIT front Integral Intensities Example 4: (2/2) complex magnetic structure, restricted front propagation EIT Wave 1 April 1997 Integral front intensity Integral dimming intensity -Integral intensity of propagating front grows in time (30 mn) symmetrically , , , with respect decrease of integral dimming intensity – regular peculiarity. NEMO Angular-Ring Analysis ESSW 3 SIDC
Extraction Int eg EIT Wave 12 May 1997 ral int en sity on Space weather applications co n ce n Tool for science investigation • Physical nature of • waves: fast/slow MHD? • dimmings: field opening, transient coronal hole ? tric • Real-time halo CME alerts: • Source identification cir cle s a • Faint undetected halos rou nd fla • First systematic event catalog rin gc • Coronal seismology en ter at 4 su cc es siv et im es • 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 NEMO ESSW 3 SIDC
2. Geometrical Extraction (1/3) CROSS-SECTION Eruption center EIT wave front dimmings NEMO 1. Solar demisphere projected on the plane 2. during an EIT wave event ESSW 3 2. 8 vertical cross-section from EC, radially 3. SIDC
Example 1: simple magnetic structure, free front propagation FRONT EXTRACTION Angular 3 D Structure of EIT wave EC EC front dimmings Under condition of free propagation rotation of EIT wave fronts observed regulary. Sense of rotation is different in the two solar hemispheres NEMO Angular-Ring Analysis ESSW 3 SIDC
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RELATION BETWEEN EIT WAVE FRONT & DIMMING NONCIRCULAR PROPAGATION OF EIT WAVE 07/04/97 14: 53 - 14: 00 14: 12 UT - 14: 00 -UT 14: 12 - 14: 00 -UT NW E d 3 W E d 1 d 2 W d 4 S S 14: 21 -14. 00 UT 14: 35 - 14: 00 UT 14: : 21 -14. 00 UT SE E W S Integral intensity of each half circle in time ANISATROPIC EIT wave structures. Dimmings NEMO ESSW 3 Velocity of structure propagation is different in SE and NW. Dimmings adjoins fronts in each directions. SIDC
07 April 1997 NEMO ESSW 3 SIDC
Phase velocities of linear waves, absence of slow mode at θ = π / 2. NEMO ESSW 3 SIDC
3. Validation (1/2) Density profile after cylindrical source explosion (Sedov like solution) Spatial coordinate time Fast mode moving upwards and slow downwards NEMO ESSW 3 SIDC
A. Detection LASCO CME 1. 1997/04/01 06: 22: 00 2. 1997/04/01 09: 24: 33 3. 1997/04/01 12: 05: 23 4. 1997/04/01 15: 18: 38 WHERE? 1. 2. 3. 4. ERUPTION MEASURE NEMO ESSW 3 SIDC
Higher-order Moments DETECTION: method Centered moment of order k: experimental: theoretical: PDF(xi) Measure of PDF asymmetry: flatness: - Skewness - Kurtosis g 1, g 2 >> 0 computed for pixels distribution of EUV image could be indicators of large scale coherent structures: for a Gaussian distribution g 1=g 2 = 0 g 1=0, g 2>0 Gaussian: g 1=g 2=0 g 1>0, g 2>0 NEMO ESSW 3 SIDC
3. Validation (2/2) NEMO ESSW 3 SIDC
Example of Daily List NEMO ESSW 3 SIDC
Architecture NEMO 5. 0 Matlab 7. 0 NEMO Detection SOHO-STEREOSWAP (onboard) Geometrical Extraction Real Time Catalog Validation SOHO scan catalog ESSW 3 SIDC
Conclusion (1/2) SIDC new product (sidc. be/nemo) ØReal-time catalog ØMonthly scan STEREO Waves NEMO ESSW 3 SIDC
Conclusion (2/2) Ø detects only eruptions, not flares. Ø can build on-disk SP. W. event catalog with SWAP and SECCHI. Ø extraction technique brings new insight on events. Ø is able to sort out the SOL. O. SDO dataflow ~TB/day. Ø Onboard realisation (CORONAS-F) NEMO ESSW 3 SIDC
Thanks To Barbara Thompson for 1997 -1998 EIT wave catalog To SIDC preview web, Cactus, B 2 X team To ESA, NASA, SECCHI/STEREO/NRL Orleans- LPCE, Meudon Obsrevatory, Florence University (European network) NEMO ESSW 3 SIDC
NEMO ESSW 3 SIDC
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