Abstract
Abstract. The representation of unresolved clouds in radiation schemes of coarse-resolution weather and climate models has progressed noticeably over the past years. Nevertheless, a lot of room remains for improvement, as the current picture is by no means complete. The main objective of the present study is to advance the cloud–radiation interaction parameterization, focusing on the issues related to model misrepresentation of cloud horizontal inhomogeneity. This subject is addressed with the Tripleclouds radiative solver, the fundamental feature of which is the inclusion of the optically thicker and thinner cloud fraction. The research challenge is to optimally set the pair of cloud condensates characterizing the two cloudy regions and the corresponding geometrical split of layer cloudiness. A diverse cloud field data set was collected for the analysis, comprising case studies of stratocumulus, cirrus and cumulonimbus. The primary goal is to assess the validity of the global cloud variability estimate along with various condensate distribution assumptions. More sophisticated parameterizations are subsequently explored, optimizing the treatment of overcast as well as extremely heterogeneous cloudiness. The radiative diagnostics including atmospheric heating rate and net surface flux are consistently studied using the Tripleclouds method, evaluated against a three-dimensional radiation computation. The performance of Tripleclouds mostly significantly surpasses the calculation on horizontally homogeneous cloudiness. The effect of horizontal photon transport is further quantified. The overall conclusions are intrinsically different for each particular cloud type, encouraging endeavors to enhance the use of cloud-regime-dependent methodologies in next-generation atmospheric models. This study, highlighting the Tripleclouds potential for three essential cloud types, signifies the need for more research examining a broader spectrum of cloud morphologies.
Highlights
1.1 General backgroundThe fundamental role of clouds and their interaction with radiation in weather and climate can hardly be overemphasized (e.g., Boucher et al, 2013; Stevens and Bony, 2013; Bony et al, 2015)
The total heating rate, a physically relevant quantity during daytime, is dominated by thermal cooling. This persistent cloud-top radiative cooling is a typical feature of marine stratocumulus-topped boundary layers (STBLs; Wood, 2012)
The focus is laid on the issues related to misrepresentation of cloud horizontal inhomogeneity in coarse-resolution weather and climate models, which are tackled with the aid of the Tripleclouds radiative solver
Summary
1.1 General backgroundThe fundamental role of clouds and their interaction with radiation in weather and climate can hardly be overemphasized (e.g., Boucher et al, 2013; Stevens and Bony, 2013; Bony et al, 2015). When interacting with solar and thermal radiation, the most common effects are radiatively induced cooling at cloud top and warming at cloud base, which promotes convective instabilities within the cloud (Webster and Stephens, 1980). This radiative destabilization of the cloud layer is impelled primarily by thermal radiation, whereas during daytime solar radiation generally has a stabilizing tendency (Crnivec and Mayer, 2019). Radiatively induced temperature changes in clouds and at the surface are firmly linked to a broad range of atmospheric moist thermo-
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
