Abstract
For a three-dimensional magnetohydrodynamics solar wind model, it is necessary to carry out assessment studies to reveal its ability and limitation. In this paper, the ambient solar wind results of year 2008 generated by the CESE-HLLD 3D MHD model are compared with multipoint in-situ measurements during the late declining phase of solar cycle 23. The near-ecliptic results are assessed both quantitatively and qualitatively by comparing with in-situ data obtained at the L1 point and by the twin STEREO spacecraft. The assessment reveals the model’s ability in reproducing the time series and statistical characteristics of solar wind parameters, and in catching the change of interplanetary magnetic field polarity and the occurrence of the stream interaction regions. We find that the two-stream structure observed near the ecliptic plane is reproduced, but the differences among observations at L1 and the twin STEREO spacecraft are not caught by the model. The latitudinal variation of the results is assessed by comparing with the Ulysses observation. The characters of variation in different latitudinal ranges are duplicated by the model, but biases of the results are seen, and the boundary layers between fast and slow solar wind are sometimes thicker than observation.
Highlights
Three-dimensional (3D) magnetohydrodynamics (MHD) ambient solar wind models are critical tools for space weather forecasting (Feng et al, 2011a, 2013; Wu & Dryer, 2015; Gombosi et al, 2018; Feng, 2020)
The first 3D MHD solar wind model transitioned into operations is the Wang–Sheeley–Arge–ENLIL (WSA–ENLIL) model (Odstrcil, 2003), which is responsible for providing 1–4 day solar wind condition forecasts upstream of the Earth, and has been updated to its 2.0 version recently (Note that version number 2.0 of the WSA– ENLIL model is different from the individual version numbers of WSA and ENLIL models)
The ambient solar wind results generated by the conservation element and solution element (CESE)-HLLD 3D MHD model during year 2008 are assessed by comparing with multipoint in-situ measurements
Summary
Three-dimensional (3D) magnetohydrodynamics (MHD) ambient solar wind models are critical tools for space weather forecasting (Feng et al, 2011a, 2013; Wu & Dryer, 2015; Gombosi et al, 2018; Feng, 2020). To validate a 3D model covering the 4p domain of the heliosphere more convincingly, it is necessary to assess its results utilizing multipoint spacecraft data Such multipoint assessment will help to further verify that the solar wind is correctly described at positions other than the L1 point, and provide more comprehensive information about the model’s strength and weakness in reproducing the global structure of ambient solar wind in the heliosphere (e.g., Pahud et al, 2012; Broiles et al, 2013; Shiota et al, 2014; Wiengarten et al, 2014; Jian et al, 2016; Merkin et al, 2016).
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