Evolution of solar wind velocity direction in the inner heliosphere

Previous statistical studies revealed that the tangential component of the solar wind velocity is positive (co-rotating) in the vicinity of the Sun but it turns its sign at about 0.2 AU. After it, this negative value increases toward 0.3 AU and gradually relaxes to zero at distances in excess of 10 AU. Since the intervals of a large negative tangential velocity component exhibit also enhanced cross-helicity, outward propagating Alfven waves generated in the outer corona were suggested as the most probable source of the observed deviation. However, the weak point of this conclusion is that the waves would deviate the solar wind velocity in all directions with the same probability. For explanation of this caveat, we use all available data gathered by PSP and analyze factors that can affect the velocity direction like waves, stream interactions or magnetic reconnection. As a result, we suggest interchange reconnection of closed lines of coronal loops with the open lines from nearby coronal hole as a most probable driver of the observed velocity reversal.  However, this type of reconnection is expected at the source regions of the slow wind whereas the negative tangential velocity component was observed in the fast wind and we discuss a scenario that can explain this objection.