Thursday

Increased accuracy in the forecasting the solar wind is important as society becomes increasingly dependent on technologies that are susceptible to space weather events. Current models are dependent on Potential-Field Source-Surface (PFSS) magnetic field extrapolations as an inner boundary condition, with the solar wind speed gained from the magnetic field configuration based on empirical comparisons. This study presents a new boundary condition based on maps of the coronal electron density, gained directly from tomography of coronagraph observations at distances where the solar wind has formed and is predominantly radial in flow (4 to 8 solar radii), thus above the complex inner corona which is most difficult to model. Using the highly-efficient HUXt solar wind model, we show that the new boundary conditions give results that compare well with PFSS-based boundary conditions for several different periods over the recent solar cycle. We experiment with different empirical relationships between the coronal density and solar wind velocity with the aim of both improving the comparison between in situ measurements and to explore the solar wind velocity profile close to the Sun. Future improvements to the tomography-solar wind model interface are described, including the possibility for constraining the solar wind acceleration at distances of 4 to 8 solar radii.