The importance of the cloud-aerosol "transition zone" in the longwave radiative budget Publication at Geophysical Research Letters 16 de novembre 2020 Recerca i transferència Publicacions
The change in the state of sky from cloudy to cloudless (or vice versa) comprises an additional phase called “transition zone,” in which the characteristics of the particle suspension lay between those corresponding to a pure cloud and those of atmospheric aerosols. This phase, however, is usually considered, in atmospheric monitoring and modeling, as an area containing either aerosol or thin clouds. This study, conducted by Babak Jahani, Josep Calbó and Josep-Abel González, members of the Environmental Physics Group, has quantified the uncertainties that that binary assumption may introduce to the estimation of longwave radiative effects at the top and bottom of the atmosphere by using the Fu‐Liou‐Gu (FLG), NewGoddard, and Rapid Radiative Transfer Model for General Circulation Model (RRTMG) radiative parameterizations included in the Weather Research and Forecasting Model. The results show that there are important differences between optically thin clouds and aerosols in longwave region, which may cause substantial uncertainties in the radiative effects at the top and bottom of the atmosphere (up to 60 W m−2) if they are used to approximate transition zone conditions. Results are important due to the role that longwave radiation plays in the radiative balance that drives the Earth's climate.The study has been conducted in the framework of the project Nubesol-2 (https://sites.google.com/view/nuclier/proyectos/nubesol-2-2020-2023) and published at Geophysical Research Letters (*). The publication is available at https://doi.org/10.1029/2020GL090408 (*) Jahani, B., Calbó, J., & González, J. A. Quantifying Transition Zone Radiative Effects in Longwave Radiation Parameterizations. Geophysical Research Letters, e2020GL090408.