  The daily cloud cycle (DCC) and its response to global warming are critical
to the Earth's energy budget, but their radiative effects have not been
systematically quantified. Toward this goal, here we analyze the radiation at
the top of the atmosphere and propose a measure of the DCC radiative effect
(DCCRE) as the difference between the total radiative fluxes with the full
cloud cycle and its uniformly distributed cloud counterpart. We apply it to the
cloud fraction from four climate models that participated in the second phase
of the Cloud Feedback Model Inter-comparison Project. The results allow us to
objectively compare inter-model differences in the daily cycle of cloud
fraction and their influences on the global energy balance. In particular, the
spatial patterns of the DCC response to global warming obtained in our analysis
suggest possible impacts on large-scale circulation. Such a framework can be
used for conducting a more systematic evaluation of the DCC in climate models
and observations with the goal to reduce uncertainty in climate projections.
