Short-term periodicities in the time series of solar radio emissions at different solar altitudes

A spectral analysis of the time series of daily values of 12 parameters, na mely, ten solar radio emissions in the range 275-1755 MHz, 2800 MHz solar r adio flux, and sunspot numbers for six continuous intervals of 132 values e ach during June 1997-July 1999 showed considerable differences from one int erval to the next, indicating a nonstationary nature. A similar to 27-day p eriodicity was noticed in Interval 2 (similar to 26.8 days), 3 (similar to 27.0 days), 5 (similar to 25.5 days), 6 (similar to 27.0 days). Other perio dicities were near 11.4, 12.3, 13.3, 14.5, 15.5, 16.5, 35, 40, 50-70 days. Periodicities were very similar in a large vertical span of the coronal reg ion corresponding to 670-1755 MHz. Above this region, the homogeneity disap peared. Below this region, there were complications and distortions due to localized solar surface phenomena.