Coronal radio-sounding detection of a CME during the 1997 Galileo solar conjunction

Frequency fluctuations of the Galileo S-band radio signal were recorded nearly continuously during the spacecraft s solar conjunction from December 1996 to February 1997 A strong propagating disturbance most probably associated with a CME was detected on 7 February from 18 30 UT to 22 30 UT when the radio ray path proximate point was on the east solar limb at about 54 solar radii from the Sun The CME passage through the line of sight is characterized by a significant increase in the fluctuation intensity of the recorded frequency and by an increase in the plasma speed from about 210 km s up to 800 km s These velocity estimates are obtained from a correlation analysis of frequency fluctuations recorded simultaneously at two widely-separated ground stations The frequency fluctuation cross-correlation functions are relatively narrow during the passage of the disturbance through the radio ray paths implying that the outward solar wind transport in the CME may be described as an ordered flow The density turbulence power spectrum is found to steepen behind the CME front The Galileo radio sounding data are compared with observations of the CME in the corona and with Wind spacecraft data near the Earth s orbit