Blending of Ground- and Space-Based Magnetograms: Application to L1-L5 Solar Wind and Coronal Hole Predictions

We examine the effect of blending ground-based Global Oscillations Network Group (GONG) line-of-sight solar magnetic flux maps ("magnetograms") with space-based magnetograms from the Solar Dynamics Observatory (SDO) Helioseismic and Magnetic Imager (HMI) instrument on solar wind and coronal hole model-based forecasts. The longitudinally blended maps are used to "reforecast" solar wind conditions using the Wang-Sheeley-Arge (WSA) solar wind model during historical periods of coronal hole High Speed Streams (HSS) and Corotating Interaction Regions (CIRs) and compared to Advanced Composition Explorer (ACE) data at the L1 Lagrangian point. The same WSA runs are repeated using GONG and HMI data alone to determine the effect of data blending. The blended maps are also used to create Potential Field Source Surface (PFSS) maps of open coronal field lines and compared with historical coronal hole data from SDO Atmospheric Imaging Assembly (AIA) images. The study addresses the feasibility of combining ground- and space-based data from instruments with widely disparate and varying spatiotemporal resolution and flux sensitivity levels for use as inputs to solar wind and coronal hole forecasting models. The results are relevant to mission studies considering blended data inputs from, e.g., L5 Lagrangian point satellite instruments with ground-based measurements on the Sun-Earth line, as well as to expected magnetogram data from the Solar Orbiter Polarimetric and Helioseismic Imager (PHI) instrument. This study complements others that examine the utility of having multiple viewpoint (e.g. L1 and L5) magnetogram inputs to solar wind models by exploring data blending from disparate instruments.