A two-dimensional Alfven-wave-driven solar wind model

This paper presents a two-dimensional, Alfven-wave-driven solar wind model, in which the wave energy is assumed to cascade from the low-frequency Alfv en waves to high-frequency ion cyclotron waves and to be transferred to the solar wind protons by cyclotron resonance at the Kolmogorov rate. A typica l structure in the meridional plane consisting of a coronal streamer near t he Sun, a fast wind in high latitudes, and a slow wind across the heliosphe ric current sheet, is found. The fast wind obtained in the polar region is essentially similar to that derived by previous one-dimensional flow-tube m odels, and its density profile in the vicinity of the Sun roughly matches r elevant observations. The proton conditions at 1 AU are also consistent wit h observations for both the fast and slow winds. The Alfven waves appear in the fast- and slow-wind regions simultaneously and have comparable amplitu des, which agrees with Helios observations. The acceleration and heating of the solar wind by the Alfven waves are found to occur mainly in the near-S un region. It is demonstrated in terms of one-dimensional calculations that the distinct properties of the fast and slow winds are mainly attributed t o different geometries of the flow tubes associated with the two sorts of w inds. In addition, the 2-D and 1-D simulations give essentially the same re sults for both the fast and the slow winds.