Height of the slowly varying component of radio emission at 9.1 cm during the Quiet Sun Years

The slowly varying component of solar microwave emission is associated with plage and sunspot regions seen optically. Under the assumption that the microwave emission originates radially above the associated optical feature the height of the microwave emission region above the photosphere can be calculated.For 99 regions seen at 9.1 cm during the International Quiet Sun Years 1964–1965 the average height was 8000 km. This result compares with 18000 km measured for the same wavelength emission during 1960. A change of height in this direction could be the result of the changing strength of the magnetic field associated with regions seen during the two periods.