  Mean field dynamo theory deals with various mean quantities and does not
directly throw any light on the question of existence of flux tubes. We can,
however, draw important conclusions about flux tubes in the interior of the Sun
by combining additional arguments with the insights gained from solar dynamo
solutions. The polar magnetic field of the Sun is of order 10 G, whereas the
toroidal magnetic field at the bottom of the convection zone has been estimated
to be 100,000 G. Simple order-of-magnitude estimates show that the shear in the
tachocline is not sufficient to stretch a 10 G mean radial field into a 100,000
G mean toroidal field. We argue that the polar field of the Sun must get
concentrated into intermittent flux tubes before it is advected to the
tachocline. We estimate the strengths and filling factors of these flux tubes.
Stretching by shear in the tachocline is then expected to produce a highly
intermittent magnetic configuration at the bottom of the convection zone. The
meridional flow at the bottom of the convection zone should be able to carry
this intermittent magnetic field equatorward, as suggested recently by Nandy
and Choudhuri (2002). When a flux tube from the bottom of the convection zone
rises to a region of pre-existing poloidal field at the surface, we point out
that it picks up a twist in accordance with the observations of current
helicities at the solar surface.
