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Between the base of the solar corona and the Alfven critical point, thesolar-wind density decreases by approximately five orders of magnitude, but thetemperature varies by a factor of only a few. In this paper, I show that suchquasi-isothermal evolution out to the Alfven critical point is a genericproperty of outflows powered by reflection-driven Alfven-wave (AW) turbulence,in which outward-propagating AWs partially reflect, and counter-propagating AWsinteract to produce a cascade of fluctuation energy to small scales, whichleads to turbulent heating. Approximating the sub-Alfvenic region asisothermal, I first present a simplified calculation of the mass outflow rate,asymptotic wind speed, and coronal temperature that neglects conductive lossesand the wave pressure force. I then develop a more detailed model of thetransition region, corona, and solar wind that accounts for the heat flux fromthe coronal base into the transition region and momentum deposition by AWs. Isolve analytically for this heat flux by balancing, within the transitionregion, conductive heating against internal-energy losses from radiation, pdVwork, and advection. The density at the coronal base is determined by locallybalancing turbulent heating and radiative cooling. I solve the equations of themodel analytically in two different parameter regimes. Analytic and numericalsolutions to the model equations agree with a number of observations.

An approximate analytic solution to the coupled problems of coronal heating and solar-wind acceleration