EUV Waves - Poster

Alexandros Koukras

Welcome to the Webpage of my Poster

This Webpage was created as suppporting material for the poster:
"Analyzing the kinematics of EUV waves by combining simulations and multi-instrument observations"

It contains three different sections Introduction , Event 1, Event 2


Introduction

Abstract:

EUV ("EIT") waves are wavelike disturbances of enhanced EUV emission that propagate away from an eruptive active region across the solar disk. We present a framework, where we treat the EUV waves as fast-mode MHD waves, study their kinematics and their connection with type II bursts. We propagate numerically a fast mode MHD wave based on the model of Uchida (Uchida 1968, 1970, 1973) and the formalism of Wang (Wang 2000;ray tracing). To accomplish that we use a 3D MHD-based coronal model (from Predictive Science Inc.) that provides density, temperature and Alfvén speed in the undisturbed coronal medium. Next, taking advantage of the high cadence and multi-wavelength observations of SDO/AIA images, we compare the propagation of the computed wavefront with the observed wave. Finally, we use the frequency drift of the type II radio bursts to track the propagating shock wave. We compare the kinematics of the simulated wavefront, identifying the most probable wave vectors that match the best the kinematics deduced from the radio emission. We focus our attention on two eruptive events on 03/04/2017 and 12/09/2017, where EUV waves are observed respectively above the limb and on the disk. We make use of a collection of high quality and multi instrument observations (PROBA2/SWAP, STEREO/SECCHI,SDO/AIA, SOHO/LASCO and the Humain, Nancy and Culgoora radio spectrographs) and combine them to better constrain the kinematics of the EUV waves.

Model:

Ushida model (1968, 1970, 1973), Wang formalism (2000)

  • In the short-wavelength WKB approximation, a magneto-hydrodynamic wave may be regarded propagating along rays that are refracted by the nonuniform coronal medium.
  • When dissipation and damping effects are neglected the propagation of a fast-mode wave is given by the equations
Model equations

Model equations, taken from Wang 2000.

MHD Coronal Model:

We use coronal data provided by global 3D MHD Coronal Models, from Predictive Science Ink.

Specifically, we focus our analysis with the new WDT model.

  • High resolution runs
  • Custom magnetogram seam

Simulation:

  • Spatial and temporal initial conditions are constrained by observations (RHESSI signatue, GOES curve)
  • Initialize the wave with a uniform distribution of initial wave vectors in all directions
  • Code written in Python
  • Parallelization, in order to be able to handle large numbers of wave-vectors
  • Validation on simple cases (topologies)

Visualization:

  • Build a 3D visualization scene using Mayavi and tvtk libraries
  • Creation of the wave-front using Delaunay 3D triangulation
  • 3D representation of the Sun surface
  • Wrap as texture to it, EUV images
  • Creation of coronal planes, which have as texture the coronal part of EUV images
  • Creation of interactive 3D animations and movies for every event
coronal data inside Mayavi

Alfven speed data inside our visualization scene.


Event 1 - April 3 2017

RHESSI image of the first event GOES plot of the first event

RHESSI image and GOES plot for Event1

Movie 1

Movie of the first event, with images from SWAP at 174 Angstrom Left panel: regular images, Right panel: running difference images.

Movie 2

Complete movie of the frames that are displayed in the poster. Left panel has a viewpoint similar to the spacecraft (S/C), right panel has a tilted viewpoint (azimuthal rotation), for better comprehension of the event.

Movie 3

Simulation of event 1 together with the type II signature. Left and right panels display the simulation but in a simple visualization without the EUV images as texture on the 3d mesh that represents the Sun surface. The central panel display the type II radio burst, with selected bourders and a vertical line that scans the radio spectrum indicating the progression in time (raypaths time steps).



PFSS image of the first event

PFSS plot for Event1


Event 2 - September 12 2017

RHESSI image of the first event GOES plot of the first event

RHESSI image and GOES plot for Event2

Movie 1

Movie of the second event, with images from AIA at 193 Angstrom. Left panel: regular images, Right panle: running difference images.

Movie 2

Complete movie of the frames that are displayed in the poster. Left panel has a viewpoint similar to the spacecraft (S/C), right panel has a tilted viewpoint (azimuthal rotation), for better comprehension of the event.

Movie 3

Simulation of event 2 together with the type II signature. Left and right panels display the simulation but in a simple visualization without the EUV images as texture on the 3d mesh that represents the Sun surface. The central panel display the type II radio burst, with selected bourders and a vertical line that scans the radio spectrum indicating the progression in time (raypaths time steps).


PFSS image of the secont event

PFSS plot for Event2


           
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