Influence of radiative forcing on Titan’s lake energy balance and sea breeze circulation

Solar and infrared radiative transfer, including the effects of scattering, have been included in the mesoscale Titan WRF (mtWRF) model of Titan’s atmosphere.  A previous study with this model in the absence of radiative forcing indicated that atmosphere-lake sensible and latent heat fluxes could diminish to magnitudes comparable to radiative fluxes due to the development of a cold and stable marine boundary layer.  Consequently, it was hypothesized that radiative forcing could be important, contrary to prior expectations, and should be included in future studies. With these results we confirm the radiative hypothesis and demonstrate that radiative forcing must be included in order to more accurately simulate the energy and mass exchange between Titan’s lakes and atmosphere. Solar heating of the lake mixed layer partially offsets the latent flux cooling during the daytime, and downwelling atmospheric IR flux provides heat to the cold lake.  Due to changes in thermal contrast between the air over the lake and the land compared to non-radiative solutions, the sea breeze atmospheric structure is altered, including the development of a pronounced diurnal circulation cycle.  All of these effects perturb the energy and mass exchange, which has local meteorological implications and exerts a control on the global methane cycle.