  The full-phase infrared light curves of low-eccentricity hot Jupiters show a
trend of increasing dayside-to-nightside brightness temperature difference with
increasing equilibrium temperature. Here we present a three-dimensional model
that explains this relationship, in order to shed insight on the processes that
control heat redistribution in tidally-locked planetary atmospheres. This
three-dimensional model combines predictive analytic theory for the atmospheric
circulation and dayside-nightside temperature differences over a range of
equilibrium temperature, atmospheric composition, and potential frictional drag
strengths with numerical solutions of the circulation that verify this analytic
theory. This analytic theory shows that the longitudinal propagation of waves
mediates dayside-nightside temperature differences in hot Jupiter atmospheres,
analogous to the wave adjustment mechanism that regulates the thermal structure
in Earth's tropics. These waves can be damped in hot Jupiter atmospheres by
either radiative cooling or potential frictional drag. This frictional drag
would likely be caused by Lorentz forces in a partially ionized atmosphere
threaded by a background magnetic field, and would increase in strength with
increasing temperature. Additionally, the amplitude of radiative heating and
cooling increases with increasing temperature, and hence both radiative
heating/cooling and frictional drag damp waves more efficiently with increasing
equilibrium temperature. Radiative heating and cooling play the largest role in
controlling dayside-nightside temperature temperature differences in both our
analytic theory and numerical simulations, with frictional drag only important
if it is stronger than the Coriolis force. As a result, dayside-nightside
temperature differences in hot Jupiter atmospheres increase with increasing
stellar irradiation and decrease with increasing pressure.
