)
transition zone located at 
which is in good agreement with the previous forward analysis carried out
on Global Oscillations Network Group (GONG),
Big Bear Solar Observatory (BBSO) and LOWL
datasets. T. Corbard - G. Berthomieu - J. Provost - P. Morel
Laboratoire G.-D. Cassini, CNRS UMR 6529, Observatoire de la Côte d'Azur, BP 4229, 06304 Nice Cedex 4, FRANCE
A&A, Received 18 July 1997; accepted 24 October 1997
Helioseismic inversions, carried out for several years on various ground-based
and spatial observations, have shown that the solar rotation rate presents
two principal regimes: a quasi-rigid rotation in the radiative interior
and a latitude-dependent rotation in the whole convection zone. The thin
layer, named solar tachocline, between these two regimes is difficult to
infer through inverse techniques because of the ill-posed nature of the
problem that requires regularization techniques which, in their global
form, tend to smooth out any high gradient in the solution. Thus, most
of the previous attempts to study the rotation profile of the solar tachocline
have been carried out through forward modeling. In this work we show that
some appropriate inverse techniques can also be used and we compare the
ability of three 1D inverse techniques combined with two automatic strategies
for the choice of the regularization parameter, to infer the solar tachocline
profile in the equatorial plane. Our work, applied on LOWL
(LOWL is an abbreviation for low degree denoted by L) two years dataset,
argue in favor of a very sharp ()
transition zone located at
which is in good agreement with the previous forward analysis carried out
on Global Oscillations Network Group (GONG),
Big Bear Solar Observatory (BBSO) and LOWL
datasets.
Sun: interior -- Sun: oscillations -- Sun: rotation -- methods: numerical