  While magnetism in exoplanets remains largely unknown, Hot Jupiters have been
considered as natural candidates to harbour intense magnetic fields, both due
to their large masses and their high energy budgets coming from irradiation as
a consequence of their vicinity to their host stars. In this work we perform
MHD simulations of a narrow day-side atmospheric column of ultra-hot Jupiters,
suitable for very high local temperatures (T > 3000 K). Since the conductivity
in this regime is very high, the dominant effect is winding due to the intense
zonal winds. By including a forcing that mimics the wind profiles obtained in
global circulation models, the shear layer induces a strong toroidal magnetic
field (locally reaching hundreds of gauss), supported by meridional currents.
Such fields and the sustaining currents don$'$t depend on the internally
generated field, but are all confined in the thin (less than a scale-height)
shear layer around 1 bar. Additionally, we add random perturbations that induce
turbulent motions, which lead to further (but much smaller) magnetic field
generation to a broader range of depths. These results allow an evaluation of
the currents induced by the atmospheric dynamo. Although here we use ideal MHD
and the only resistivity comes from the numerical scheme, we estimate
a-posteriori the amount of Ohmic heat deposited in the outer layers, which
could be employed in evolutionary models for Hot Jupiters' inflated radii.
