The Three-Dimensional Structure of the Solar Wind from Radio Scintillations.
Abstract
Since 1972 the UCSD 74 MHz radio observatory has continuously monitored the solar wind using the method of interplanetary scintillation (IPS). The two reports presented here bear on the problems involved in tracing the fast changing three dimensional structure of the solar wind from the solar surface out to the vicinity of the earth. The interplanetary scintillation technique is a radio propagation method for studying the velocity and small scale (approximately 100 to 1000 km) turbulence in the solar wind. The signals are cross-correlated from three spaced antennas to yield time offsets from which the speed of the scintillation pattern can be deduced. Comparisons of IPS observations with spacecraft measurements have shown excellent agreement when the IPS source lies in the ecliptic plane. Since our equipment relies on the use of natural radio sources, we are not restricted to observations in the ecliptic. Furthermore, observations can be made in the direction of many radio sources (almost) simultaneously so as to generate a three-dimensional map of the solar wind. The eight-year data base is important for correlative studies throughout the solar cycle. In our analysis we emphasize three time scales: (a) the solar cycle evolution of six month average velocity structures; (b) studies of one solar rotation duration; and (c) variations in the solar wind structure on time scales of a few days.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1981
- Accession Number
- ADA108152
Entities
People
- A. Nagendran
- B. V. Jackson
Organizations
- University of California