The 2800-MHz Solar Radio Minimum of February 1976
Abstract
The total daily 2800-MHz solar flux observed at Algonquin Radio Observatory, Lake Traverse, Ontario, during the recent sunspot minimum has been analyzed for simultaneously occurring values of the basic quiet sun and of the slowly varying component (SVC). Values of 67.5 and 2.7 solar flux units (sfu), respectively, were found to have occurred in February 1976. Previous radio minima were in July 1964, with values of 67.2 and 4.9 sfu, and January 1954, with values of 65.0 and 3.1 sfu. The basic quiet-sun levels for 1976 and 1954 appeared intermittently several months before the two-parameter minima, while in 1964 the basic quiet sun appeared only once, for a duration of three days. The average values of the fluctuating SVC for twelve months centered on the minima of 1954, 1964 and 1976 were 8.0, 6.8, and 15.4 sfu, respectively. The high value in 1976 corresponds to the highest sunspot minimum in 250 years of sunspot records, according to Waldmeier (1977).
- Publication:
-
Journal of the Royal Astronomical Society of Canada
- Pub Date:
- February 1979
- Bibcode:
- 1979JRASC..73....1C
- Keywords:
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- Solar Activity Effects;
- Solar Flux Density;
- Solar Radio Emission;
- Sunspots;
- Ultrahigh Frequencies;
- Electromagnetic Spectra;
- Microwave Emission;
- Radio Astronomy;
- Sunspot Cycle;
- Solar Physics