NEMO ESSW3 SIDC
http://sidc.be/nemo
"To understand is to perceive patterns"
ROB
NEMO ESSW3 SIDC
EIT Wave Detector
Motivation EIT waves quantitative properties
Free propagation Interaction with ARs
Properties - Models
NEMO software Architecture Recognition & Diagnostic,
Catalogue
in real time
NEMO ESSW3 SIDC
Solar Eruptions in Real time
Flares
CMEs
“Gopalswamy” list http:/sidc.be/cactus
SEC events at NOAA, SXI SolarSoft events B2Xflare
NEMO ESSW3 SIDC
Importance of On-Disk Eruptionsgeoeffectivity
SOHO is in the L1 Lagrange point
in the Solar-Terrestrial System,
and goes around the Sun simultaneously with the Earth.
SOHO profits continuous view of the Sun.
NEMO ESSW3 SIDC
FOV: 45 arcmin FOV: 54 arcmin
1.67 R
2.36 R
Typically (CME watch): Cadence: 12 minCentral wavelength: 19.5 nm
Cadence: 1 minCentral wavelength: 17.5 nm
NEMO ESSW3 SIDC
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/http://stereo.nrl.navy.mil/
NEMO ESSW3 SIDC
How does Eruption look like in EUV?
“EIT wave”precursor
Original Image Image substructed from prevrious one
Discovery: Thompson et al, 1998; On disk CME signatures: Biesecker & Thompson, 2002
NEMO ESSW3 SIDC
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.
NEMO ESSW3 SIDC
NEMO version 5.00 in MATLAB 7
DETECTION of event occurrence
DIMMING extraction from EUV image
EIT WAVE extraction from EUV image
Higher order moments technique (applied to EUV image pixels distribution)
method to detect coherent large scale structure in white noise
Progressive Growth of intensive dimming region
Ring Analysis (for automatic calculation of radial velocity of the EIT wave)
Angular-Ring Analysis (to quantify the angular rotation of EIT wave )
NEMO ESSW3 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 intensityd). Selected region of negative intensity, corresponding to the full size of the dimmings
NEMO ESSW3 SIDC
Dimmings: Spatial properties1. Dimmings are extracted rigorously, defined:
•Their area
•Integral and differential intensity; structureAssumption: 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:
04:50 UT 05:07 UT
05:24 UT 05:41 UT
EIT wave 12/05/97N
E
S
W
N
E
S
W
N
E
S
W
N
E
S
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NEMO ESSW3 SIDC
EIT wave quantities will depend explicitly on:
Distance from eruption center, i.e. length of r (defined on sphere)
Direction of radius-vector
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
FRONT EXTRACTION
Basic principles
Algorithms based on the principles:
NEMO ESSW3 SIDC
mm
Eruption Center
into
lin
e
Synhronous propagation of the peak in sectors
FRONT EXTRACTION
Extraction techniques
Ring integral intensity
into
pix
el
Angular-Ring Analysis Ring Analysis
NEMO ESSW3 SIDC
Peak propagation used for automatic definition of radial velocity
FRONT EXTRACTION
Ring analysis
Example 1: (1/4)simple magnetic structure, free front propagation
Extracted Front Evolution EIT Wave 12 May 1997(1/4)
NEMO ESSW3 SIDC
Rotation
of fronts !
Morphological similarities between fronts and dimmings!
FRONT EXTRACTION
Angular-Ring Analysis
Example 1: (3/4)simple magnetic structure, free front propagation
Hot loop overlap
dimmings
EC
front
Angular 3D Structure of EIT waveEIT Wave 12 May 1997 (3/4)
NEMO ESSW3 SIDC
Integral front intensity
Integral dimming intensity
Angular-Ring Analysis
FRONT EXTRACTION
Example 4: (2/2)complex magneticstructure, restricted front propagation
Dimmings and EIT front Integral Intensities EIT Wave 1 April 1997
-Integral intensity of propagating front grows in time (30 mn) symmetrically ,,,with respect decrease of integral dimming intensity – regular peculiarity.
NEMO ESSW3 SIDC
EIT Wave 12 May 1997 Integral intensity on concentric circles around flaring center at 4 successive times
Space weather applications
•Real-time halo CME alerts:•Source identification•Faint undetected halos
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
Extraction
NEMO ESSW3 SIDC
2. Geometrical Extraction (1/3)
dimmings
EIT wave front
Eruption center
1.1. Solar demisphere projected on the planeSolar demisphere projected on the plane
during an EIT wave event during an EIT wave event 2.2. 8 vertical cross-section from EC, 8 vertical cross-section from EC,
radiallyradially
CROSS-SECTION
NEMO ESSW3 SIDC
Under condition of free propagation rotation of EIT wave fronts
observed regulary. Sense of rotation is different in the two solar
hemispheres
FRONT EXTRACTION
Angular-Ring Analysis
Example 1:simple magnetic structure, free front propagation
dimmings
EC
front
dimmings
EC
front
Angular 3D Structure of EIT wave
NEMO ESSW3 SIDC
NEMO ESSW3 SIDC
NEMO ESSW3 SIDC
14:12 - 14:00 -UT
14:21-14.00 UT14:35 - 14:00 UT
14:53 - 14:00 UT
S
WE
S
WE
RELATION BETWEEN EIT WAVE FRONT & DIMMING NONCIRCULAR PROPAGATION OF EIT WAVE 07/04/97
S
WE
S
WE
d1
d2d3
d4
14:12 - 14:00 -UT
14::21-14.00 UT
ANISATROPIC EIT wave structuresDimmingsIntegral intensity of each half circle in time
SE
NW
Velocity of structure propagation is different in SE and NW. Dimmings adjoins fronts in each directions.
NEMO ESSW3 SIDC
07 April 1997
NEMO ESSW3 SIDC
Phase velocities of linear waves, absence of slow mode at θ = π / 2.
NEMO ESSW3 SIDC
0 0.2 0.4 0.6 0.86
8
10
12
14
Fast mode moving upwards and slow downwards
time
Spatial coordinate
Density profile after cylindrical source explosion (Sedov like solution)
3. Validation (1/2)
NEMO ESSW3 SIDC
4.
3.
2.
1.
15:18:381997/04/01
12:05:231997/04/01
09:24:331997/04/01
06:22:00 1997/04/01
LASCO CMELASCO CME
1.1.
2.2. 3.3.
4.4.
WHERE?WHERE?
ERUPTION MEASUREERUPTION MEASURE
A. Detection
NEMO ESSW3 SIDC
Centered moment of order k:
experimental:PDF(xi)
theoretical:
Measure of PDF
asymmetry:
- Skewness
Gaussian: 1=2=0
1=0, 2>0
DETECTION: method
flatness:
- Kurtosis
1>0, 2>0
1,2 >> 0 computed for pixels distribution of EUV image could be indicators of large scale coherent structures:
for a Gaussian distribution 1=2 = 0
Higher-order Moments
NEMO ESSW3 SIDC
3. Validation (2/2)
NEMO ESSW3 SIDC
Example of Daily List
NEMO ESSW3 SIDC
Architecture
NEMO 5.0NEMO 5.0Matlab 7.0Matlab 7.0
DetectionDetection
Real Time CatalogReal Time CatalogGeometrical Geometrical ExtractionExtraction
ValidationValidation SOHO scan catalogSOHO scan catalog
SOHO-STEREO-SOHO-STEREO-SWAP (onboard)SWAP (onboard)
NEMO ESSW3 SIDC
Conclusion (1/2)
SIDC new product (sidc.be/nemo)Real-time catalog Monthly scan
STEREO Waves
NEMO ESSW3 SIDC
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)
Conclusion (2/2)
NEMO ESSW3 SIDC
Thanks
To Barbara Thompson for 1997-1998 EIT wave catalogTo SIDC preview web, Cactus, B2X teamTo ESA, NASA, SECCHI/STEREO/NRLOrleans- LPCE, Meudon Obsrevatory, Florence University (European network)
NEMO ESSW3 SIDC