WP6 - Numerical Modelling

Introduction:

The primary goal of WP6 is to transform the catalogues of CMEs and CIRs observed by HI, accomplished in WP2/3 and WP5, into more advanced catalogues of simulations results of CIRs and CMEs. This advanced database will provide to the space community a set of simulation results optimised by assimilating direct images of the solar wind into ENLIL simulations. The delivery of these advanced catalogues will enhance forefront research on the ‘background’ solar wind (fast and slow solar wind) and on the spatial and temporal evolution of CIRs and CME shocks, and will provide unique material to study and interpret particle radiation measurements in the inner heliosphere. This resource will also be useful to assess the potential role of HI images for space-weather predictions and to prepare future missions (e.g. ESA’s Solar Orbiter).

The work package consists of three tasks.

  • Assimilating HI images to model the background solar wind
  • Assessing the use of HI to initialize ENLIL
  • Continual assimilation of HI data in ENLIL and comparison with standard implementation techniques

Methodology:

The work package will assess the use of HI observations of solar wind streams to initialise numerical models of the background solar wind. In the case of CMEs the task will be to investigate the use of HI observations to inject transients in numerical models of the background solar wind and to compare initialisation techniques of MHD codes with HI-assimilated initialisation techniques. An important output will be to establish a catalogue of numerically-predicted CME and shock impacts at in-situ spacecraft and a catalogue of optimised background solar wind and CME simulation results.

Task 1: Assimilating HI images to model the background solar wind

The combination of the catalogues of CIRs derived in WP5.1 and WP5.2, J-maps derived from HI images and movies will be compared with synthetic J-maps and movies of CIRs derived from numerical simulations of the background solar wind (ENLIL). We will divide events in two classes: Class 1 for which a good correspondence is immediately obtained between simulated and observed height-time maps and Class 2 for which J-maps differ significantly. We will compare how well ENLIL predicts the in-situ measurements of CIRs for these two classes of events separately. We will then modify the coronal input of ENLIL of the second class of events until synthetic and observed J-maps are in good agreement. We will then quantify the improvement in the predicted simulations by a statistical comparison of results with in-situ measurements of CIRs. A catalogue of the most accurate set of simulations of the background solar wind will then be established. This catalogue will be very useful for further simulations or for scientific users to obtain a more accurate estimate of the magnetic connectivity of spacecraft with solar events.

Task 2: Assessing the use of HI to initialize ENLIL

The results of WP3 and 4 will provide the central axis, volume and speed of CMEs between 10 and 20 solar radii (range of inner boundary for ENLIL). These CMEs will then be injected as hydrodynamic spheres into the most accurate simulations of the background solar wind derived from Task 1. The arrival time of the leading edge of the CMEs and the properties of the potential shocks driven ahead of them will be compared with in-situ measurements (exploiting the results of WP4.2). A catalogue of these optimised ENLIL simulations of CMEs and their shocks will then be stored for the ecliptic plane. This advanced catalogue will help studies of the origin of solar energetic particle events.

Task 3: Continual assimilation of HI data in ENLIL and comparison with standard implementation techniques

In Task 2, the CME properties are specified once at the inner boundary. The CME position, volume and speed can be updated every 40 minutes for HI-1 and 2 hours for HI-2. Medium resolution ENLIL simulations will be re-launched at every time step such that the CME position and speed remains in agreement with HI images. The results of this set of assimilated simulations will be compared with results of WP5.2 and in-situ measurements; we will determine whether a continual assimilation of HI images provides a better forecast of CME arrival times at 1 AU.

Deliverables:

Deliverable Number Deliverable Title Leader Delivery Month
D6.1 Assessment of how well ENLIL predicts the properties of CIRs using HI UPS 24
D6.2 Catalogue of optimised ENLIL simulations UPS 24
D6.3 Catalogue of shocks of obtained using ENLIL UPS 36
D6.4 Assessment of the use of HI/ENLIL for space-weather forecasting UPS 36

Other Outputs:

Description of work package.

Schedule:

Description of work package.



Current Status:

Description of work package.