Interplanetary scintillation measurements of the solar wind above low-latitude coronal holes Original Research Article

Observations of interplanetary scintillation (IPS) made using the EISCAT facility provide accurate measurements of solar wind velocity between 15 and 120 solar radii. In this paper we present observations of the solar wind at low latitudes made between 1994 and 1997. Of 178 observations of the solar wind at low heliographic latitudes, 112 showed evidence of flow velocities significantly faster than the normal slow wind across a portion of the ray-path. In all cases, these enhanced flow speeds were clearly associated with coronal holes extending towards or across the heliographic equator. Fast flow from very close to the heliographic equator is clearly associated with equator-crossing coronal holes in all cases, suggesting that discrete streams of fast wind observed at low latitudes originate exclusively in coronal holes.