Interplanetary Scintillation (IPS) measurements obtained from a large
number of compact radio sources (nearly 150 sources) distributed over
the heliocentric distance range 15-175 solar radii (R.) and heliograph
ic latitude similar to 75 degrees N-75 degrees S have been used to stu
dy the global three-dimensional density distribution of the solar wind
plasma. Contours of constant electron-density fluctuations (Delta N-e
) in the heliospheric plasma obtained for both the solar minimum and m
aximum show a strong solar latitude dependence. During low solar activ
ity, the equatorial density-fluctuation value decreases away from the
equator towards higher latitudes and is reduced by similar to 2.5 time
s at the poles; the level of turbulence is reduced by a factor of simi
lar to 7; the solar-wind mass flux density at the poles is similar to
25% lower than the equatorial value. However, during high solar activi
ty, the average distribution of density fluctuations becomes spherical
ly symmetric. In the ecliptic, the variation of Delta N-e with the hel
iocentric distance follows a power law of the form R(-2.2) and it does
not show any change with solar activity.