Comparison of MHD Simulations of the Solar Wind with In-Situ Measurements
Abstract
ENLIL is a time-dependent 3D MHD model to simulate the structure and evolution of the solar wind parameters in the inner and mid heliosphere. ENLIL can be coupled to the coronal models "Magnetohydrodynamics Around Sphere" (MAS) and "Wang-Sheeley-Arge" (WSA) which use synoptic magnetograms of the solar photosphere as input parameter. We tested the performance of the coupled models ENLIL/MAS and ENLIL/WSA by comparing the modeled solar wind speed, proton density, temperature, and radial and total magnetic field strength to in-situ measurements from Wind and ACE at 1 AU. For the comparison we chose the year 2005 as a time period with low solar activity. We requested model runs with the aim to produce a stationary solution of the background solar wind. All simulations were carried out by CCMC/NASA. For the analysis of the model results we extracted the data at the exact position of the spacecraft. We calculated correlation coefficients to quantify the agreement between model predictions and measurements. The accuracy of the predicted arrival times of solar wind structures was quantified by carrying out cross-correlations. The results show that ENLIL/MAS and ENLIL/WSA are able to simulate the general features of the background solar wind and to reproduce recurring structures in the heliosphere. The best results were obtained for the parameter solar wind speed. However, the predicted arrival times of high speed solar wind streams have typical uncertainties of the order of 1 - 1.5 days, and the absolute values of the magnetic field were systematically too low. The sector structure of the interplanetary magnetic field was well reproduced by both models.
- Publication:
-
Solar Heliospheric and INterplanetary Environment (SHINE 2012)
- Pub Date:
- June 2012
- Bibcode:
- 2012shin.confE..31G