  We have calculated the effects of large scale solar flows like the meridional
circulation, giant convection cells and solar rotation on the helioseismic
splitting coefficients using quasi-degenerate perturbation theory (QDPT). Our
investigation reveals that the effect of poloidal flows like the large scale
meridional circulation are difficult to detect in observational data of the
global acoustic modes since the frequency shifts are much less than the errors.
However, signatures of large scale convective flows may be detected if their
amplitude is sufficiently large by looking for frequency shifts due to nearly
degenerate modes coupled by convection. In this comprehensive study, we attempt
to put limits on the magnitude of flow velocities in giant cells by comparing
the splitting coefficients obtained from the QDPT treatment with observational
data.
