Flux of Radio Emission from the Sun with a Wavelength of 10.7 cm (2800 MHz)
After the discovery of the radio emission of the Sun in 1947, a new index of solar activity was introduced -
flux of radio emission
F10.7 with a wavelength of 10.7 cm (2800 MHz).
It is measured in solar flux units: 1 sfu = 10-22W/(m2·Hz).
This index characterizes changes in temperature and density
on the entire visible disk of the Sun. Its changes correlate well with changes in Wolf numbers and
of the total area of spots and is a convenient daily characteristic of solar activity.
Daily measurements of the integrated emission from the solar disk at 2800 MHz (10.7 cm wavelength) are carried according to the Sun
monitoring program by the National Research Council of Canada from 1947. Until May 31, 1991, observations were made at the Algonquin
Radio Observatory, near Ottawa. Since June 1, 1991, observations have been carried out at the
Dominion Radio Astrophysical Observatory, located near Penticton, British Columbia.
The results of observations in the form of daily, monthly and yearly values of F10.7 emissions are published on
the website of the National Centers for Environmental Information, NOAA (USA) in the
"Solar Indices" section.
Data are presented in three forms: obs – observed values measured by the solar radio telescope;
adj – adjusted values corrected for the change in Earth-Sun distance
and reduced to the mean distance;
abs – absolute values - adjusted values multiplied by 0.9.
Data for the period 1947-1999 were obtained from the former WDC-A for STP (USA) and are continued to date with values published
by the National Centers for Environmental Information.