Large-scale structure of solar wind turbulence near solar activity minimum

Abstract

Interplanetary scintillation measurements at 327MHz taken in 1997 are used to study the large-scale heliospheric structure near the solar activity minimum. Our data show that density fluctuations in the fast polar wind is much less than those of the slow wind around the equator. The reduction ratio of the fast wind turbulence is estimated to be about 0.53 from the model calculation. While an inverse relation between wind speed and density fluctuations appears to exist, the correlation is weak, and there are significant discrepancies in the locations of high turbulence and slow wind speed. This discrepancy might come from the integration effect along the line-of-sight and/or the effect of the stream-stream interaction.