Thursday

Inner boundary conditions for solar wind models are either directly or indirectly based on magnetic field models, thus the only direct observational constraint is the smoothed photospheric field. Between the photosphere and Earth, there are no other direct empirical constraints on models, other than techniques based on hindcasting of in situ measurements. New breakthroughs in coronal rotation tomography, applied to coronagraph observations, allow maps of the coronal electron density to be made in the heliocentric height range 4-12 solar radii (Rs). We show that these maps (i) give a new empirical boundary condition for solar wind structure at a height where the coronal magnetic field has become radial, thus avoiding the need to model the complex inner coronal magnetic field, (ii) give accurate rotation rates for the corona, of crucial importance to the accuracy of solar wind models and forecasts, and (iii) open the possibility for constraining the slow solar wind acceleration at the model base. The tomography maps also allow a direct constraint on the model density, which may be propagated outwards giving predictions for both solar wind speed and density at 1AU.