Solar wind temperature and speed.

Abstract

When it is averaged on a time scale of several solar rotations, the solar wind proton temperature T increases monotonically with the bulk speed V (Hundhausen et al., 1970; Burlaga and Ogilvie, 1970). This macroscale T-V relation does not change appreciably with solar cycle. The temperatures corresponding to intervals of increasing speed are only 15% higher than those corresponding to decreasing speeds, and thus it is indicated that the macroscale T-V relation is not appreciably affected by stream interactions. On a time scale of a tenth of a solar rotation there are time dependent T(t)-V(t) relations that are closely related to the stream profiles, as was noted by Hundhausen (1973). These T(t)-V(t) relations can meaningfully be resolved into two components - the macroscale T-V relation and systematic time dependent deviations from the macroscale relation.