This diagram shows the solar rotation rate inferred from two months of MDI Medium-l data as a function of radius at three latitudes, 0 degrees, 30 degrees, and 60 degrees.
The Medium-l data are spatial averages of the full-disk Doppler velocity out to ninety percent of the Sun's radius, measured each minute. This MDI observational program results in 23,000 bins of approximately ten arcsecond resolution, which, in turn, provides sensitivity to solar p mode frequency oscillations up to degree l=300 of the spherical surface harmonic modes.
You can also download a postscript version of the above figure.
You can find more about this result from the
preprint, (1.4Mb,postscript) titled:
Internal Structure and Rotation of the Sun:
First Results from the MDI Data, by
J. Schou, P.H. Scherrer, R.S. Bogart, R.I. Bush, J.T. Hoeksema,
J. Aloise, L. Bacon, A. Burnette, C. DeForest, P.M. Giles,
L. Leibrand, R. Nigam, M.Rubin, K. Scott, S.D. Williams, S.Basu,
J. Christensen-Dalsgaard, W. Dappen, R.J. Rhodes,Jr., T.L. Duvall,
Jr., R. Howe, J.J. Thompson, D.O. Gough, T. Seikii, J. Toomre,
T.D. Tarbell, A.M. Title, D. Mathur, M. Morrison, J.L.R. Saba,
C.J. Wolfson, I. Zayer, and P.N. Milford.
SOHO SOI/MDI Results.
The SOI Main Page.