Blending of Ground- and Space-based Solar Magnetograms: an L5 Mission Imperative?

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 current L1 and L5 space weather mission plans that specify different instrument sets and will thus require complex data blending to provide forecasting model inputs.