LATITUDINAL VARIATION OF SOLAR-WIND VELOCITY

Single station solar wind velocity measurements using the Ooty Radio T elescope (ORT) in India (operating at 327 MHz) are reported for the pe riod August 1992 to August 1993. Interplanetary scintillation (IFS) ob servations on a large number of compact radio sources covering a latit udinal range of +/-80 degrees were used to derive solar wind velocitie s using the method of fitting a power law model to the observed IFS sp ectra. The data shows a velocity versus heliographic latitude pattern which is similar to that reported by Rickett and Coles (1991) for the 1981-1982 period. However, the average of the measured equatorial velo cities are higher, being about 470 km s(-1) compared to their value of 400 km s(-1). The distribution of electron density variations (Delta N-e) between 50R. and 90R. was also determined and it was found that D elta N-e was about 30% less at the poles as compared to the equator.