First simultaneous in situ measurement of electron density and electric field fluctuations during spread F in the Indian zone

The paper presents results of in situ measurements of electron:density and electric field fluctuations (delta n(e), delta E-v' and delta E-H') during a strong spread F event from the SHAR rocket, range in India. Intermediate scale n(e) irregularities were observed in the F region valley over SHAR, w hich was earlier found to be free from irregularities. Experimental evidenc e of the validity, of the image striation theory is provided through first Simultaneous spectral measurement of electron density and electric field in the valley region. Correlation analysis of delta n(e), delta E-v' and delt a E-H' suggests the existence of a sheared flow of current below the F-peak . A new type of irregularity in the intermediate scale having a steep spect rum (n = -3.1) has also been detected in the valley region. A very sharp la yer of ionization wherein the electron density increased by a factor of 50 in 10 km vertical extent was detected at 105 km.