Power spectral characteristics of ESF irregularities during magnetically quiet and disturbed days

Amplitude scintillations on 251 MHz signal recorded by spaced receivers at Tirunelveli (8.7°N, 77.8°E, dip latitude 0.6°N) for eight months during 1995–2005 are utilized in present work. Power spectral analysis of weak scintillations (0.15≤S4≤0.5)(0.15≤S4≤0.5) is carried out and spectral index, m   of ESF irregularities, is computed for quiet and disturbed days. Maximum cross-correlation, CI(x0,tm)CI(x0,tm), of intensity variations between two receivers is used to identify the fresh generation of EPBs resulted from magnetic activity. Increase in F-region height is seen prior to the generation of these fresh EPBs and associated ESF irregularities found to possess shallower power spectrum.

► Disturbed days with freshly generated EPBs are likely to have small scale length.
► Spectral slope is found to decrease with decrease in maximum cross-correlation CICI.
► Enhancement in h′Fh′F is seen prior to the fresh generation of EPBs on disturbed days.