P2D – A two-dimensional solar wind persistence model

The background solar wind is one of the most crucial aspects in space weather forecasting. It is the environment through which coronal mass ejections propagate, impacting their geo-effectiveness. Due to the solar rotation and the slow evolution of solar sources of the solar wind, solar wind parameters exhibit an autocorrelation with a period of roughly 27 days. We make use of this property and produce a solar wind persistence model with input from multiple spacecraft (Solar Orbiter, Parker Solar Probe, STEREO-A and OMNI) projected onto the ecliptic. We present the statistical performance of the persistence model. The model propagates in-situ data from the position of their measurement radially away from the Sun, as well as longitudinally with the solar rotation rate.  We combine measurements from different spacecraft into one solar wind forecast at Earth using error estimates from a statistical evaluation of solar wind persistence across radial, longitudinal, and latitudinal separation. Due to the long persistence of the solar wind, the model does not rely heavily on real-time measurements but rather can use weeks-old in-situ measurements from all the spacecraft. The source code and model output will be made publicly available.