Reconstructing Coronal Hole Areas With EUHFORIA and AdaptedWSA Model: Optimizing the Model Parameters

The adoptedWang-Sheeley-Arge (WSA) model embedded in EUHFORIA (EUropean Heliospheric FORecasting Information Asset) is compared to EUV observations. According to the standard paradigm, coronal holes are sources of open flux; thus, we use remote sensing EUV observations and catch (Collection of Analysis Tools for Coronal Holes) to extract CH areas and compare them to the open flux areas modeled by EUHFORIA. From the adopted WSA model we employ only the Potential Field Source Surface (PFSS) model for the inner corona and the Schatten Current Sheet (SCS) model for the outer (PFSS+SCS). The height, Rss, of the outer boundary of the PFSS, known as the source surface, and the height, Ri, of the inner boundary of the SCS are important parameters affecting the modeled CH areas. We investigate the impact the two model parameters can have in the modeled results.We vary Rss within the interval [1.4, 3.2]R⊙ with a step of 0.1R⊙, and Ri within the interval [1.3, 2.8]R⊙ with the same step, and the condition that Ri < Rss. This way we have a set of 184 initial parameters to the model, and we assess the model results for all these possible height pairs.We conclude that the default heights used so far fail in modeling accurately CH areas and lower heights need to be considered.status: Published onlin