Improving Modelling Areas of Open-Closed Flux in the Corona Using Remote Sensing Observations
Abstract
Modelling the open magnetic field in the heliosphere with high accuracy is essential for space weather forecasting purposes. Primary source of open magnetic field are Coronal Holes (CH). Therefore, when assessing how well we model the open magnetic field one needs to test how well the model performs on one of its fundamental functions, that of reconstructing coronal hole areas. For our study, we used EUHFORIA (European heliospheric forecasting information asset) model which employs an empirical solar wind model that combines the Potential Field Source Surface (PFSS) and the Schatten Current Sheet (SCS) models. Two important free parameters of the PFSS and the SCS models are the source surface height (the outer boundary of the PFSS) and the height of the inner boundary of SCS. Although, a commonly used value for the source surface height is that of 2.5 solar radii, a wider range of allowed heights ranging from 1.5 to 3.25 solar radii exist. Here, we investigate the optimal heights that one should preselect in the model aiming for better reconstruction of open flux areas. We vary the source surface height within the interval [1.4, 3.2]Rs with a step of 0.1Rs, and the SCS inner boundary height within the interval [1.3, 2.8]Rs with the same step, where Rs is one solar radius. The study is applied on 15 CH exhibiting different latitudinal position and geometry. We compare the modelled open flux areas with CH boundaries extracted using remote sensing EUV observations and CATCH (Collection of analysis tools for coronal holes). This study indicates that lower values of the two boundary heights improve the modelling results. EUV image data from instruments having a wide field of view, such as SUVI on board GOES-R, and SWAP on board PROBA2, offer unprecedented possibility to actually observe the heights below which closed loops exist in the corona, and therefore further constrain the height choices in the model by providing a lower limit.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMSH13A..09A
- Keywords:
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- 7509 Corona;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7513 Coronal mass ejections;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7594 Instruments and techniques;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY