Use of Interplanetary Scintillation for Earth Space Environment and Geomagnetic Forecasting

摘要

A comparison is presented between solar wind velocities determined from IPS (Interplanetary Scintillation) observations made from 1973 to 1981 with those measured in situ by spacecraft instruments. The IPS method is indirect but it provides reasonably accurate estimates of the large scale and slowly varying velocity structures in the solar wind. Thus the corotating solar wind streams typical of 1973-75 (declining and low solar activity) are well estimated; the slower average speed typical of 1979-81 was also well estimated. However, the transient increases during this period of high solar activity were often not detected. The difficulties of interpretation are offset by the capacity to monitor the solar wind speed out of the ecliptic and over long periods of the time without the expense of a spacecraft.