In this talk, we review the three-dimensional evolution of the solar<br />
wind density and speed distributions in the inner heliosphere. The<br />
primary solar wind data used in this study has been obtained from the<br />
interplanetary scintillation (IPS) measurements made at the Ooty Radio<br />
Telescope, which is capable of measuring scintillation of a large number<br />
of radio sources per day and solar wind estimates along different cuts<br />
of the heliosphere, allow to image the three-dimensional structure of<br />
the ambient solar wind and propagating transients (CMEs or CIRs) in the<br />
Sun-Earth distance range. Results indicate that (1) the interaction<br />
between the CME (or the CIR) and the background solar wind determines<br />
the radial evolution of its speed and size, (2) the magnetic energy<br />
associated with the propagating transient (the magnetic cloud in the<br />
case of a CME and the high-speed stream for a CIR) is likely to play<br />
a crucial role in determining the effectiveness of the compression <br />
and propagation characteristics of the disturbance. Ooty studies play <br />
a key role in quantifying the drag force imposed on disturbances by <br />
the solar wind interaction, which is essential in modeling the <br />
propagation characteristics of disturbances within 1-AU heliosphere.<br />
Such studies also have a great importance in understanding the <br />
prediction of CME/CIR-associated space weather at near-Earth space.<br />