  There is mounting evidence that the ejection of magnetic helicity from the
solar surface is important for the solar dynamo. Observations suggest that in
the northern hemisphere the magnetic helicity flux is negative. We propose that
this magnetic helicity flux is mostly due to small scale magnetic fields; in
contrast to the more systematic large scale field of the 11 year cycle, whose
helicity flux may be of opposite sign, and may be excluded from the
observational interpretation. Using idealized simulations of MHD turbulence as
well as a simple two-scale model, we show that shedding small scale (helical)
field has two important effects. (i) The strength of the large scale field
reaches the observed levels. (ii) The evolution of the large scale field
proceeds on time scales shorter than the resistive time scale, as would
otherwise be enforced by magnetic helicity conservation. In other words, the
losses ensure that the solar dynamo is always in the near-kinematic regime.
This requires, however, that the ratio of small scale to large scale losses
cannot be too small, for otherwise the large scale field in the near-kinematic
regime will not reach the observed values.
