Enhanced Cloud Top Longwave Radiative Cooling Due to the Effect of Horizontal Radiative Transfer in the Stratocumulus to Trade Cumulus Transition Regime
Recent studies developed the SPeedy Algorithm for Radiative TrAnsfer through CloUd Sides (SPARTACUS) to handle the influence of horizontal RT on vertical radiative fluxes within an atmospheric column. The present study applies SPARTACUS to large eddy simulation (LES)-generated cloud fields across the stratocumulus to trade cumulus transition (STCT) regime with coarse and fine vertical resolutions. The results show that, as the vertical resolution increases, radiation simulations show increasingly stronger cloud-top longwave (LW) radiative cooling. Consequently, the sharp radiative heating gradient across the cloud layer in the LES-like resolution simulations cannot be resolved with the coarse resolution simulations. Including the horizontal RT typically enhances cloud LW radiative cooling rate by less than 10% for all the cloud fields but more significantly in the cloud fields during the STCT. The enhanced cloud LW radiative cooling also occurs in the lower cloud layer in the decoupled cumulus cloud regime.
In conventional climate studies, the intricate interplay of light within clouds, particularly from the sides, is often overlooked. Recent advancements have introduced a more efficient method for accounting for lateral light transfer in cloud modeling. This study employs this novel approach to examine how different configurations of low-level clouds, generated by computer models, influence atmospheric heating. Our findings demonstrate that providing finer details of cloud structures leads to a cooling effect at the uppermost regions of the clouds.
In conventional climate studies, the intricate interplay of light within clouds, particularly from the sides, is often overlooked. Recent advancements have introduced a more efficient method for accounting for lateral light transfer in cloud modeling. This study employs this novel approach to examine how different configurations of low-level clouds, generated by computer models, influence atmospheric heating. Our findings demonstrate that providing finer details of cloud structures leads to a cooling effect at the uppermost regions of the clouds. This emphasizes the importance of representing clouds in high resolution for accurate climate assessments. Moreover, when lateral light transfer is considered, the cooling effect intensifies across various cloud patterns. This phenomenon is most pronounced during the transition from uniform dispersion to a more scattered distribution of clouds. Additionally, we observed this cooling effect in the lower cloud layer when clouds are in a scattered formation.