The seasonal cycle of cloud radiative effects over Congo Basin based on CERES observation and comparison to CMIP6 models

• Published in: Atmospheric research 2023-08, Vol.291, p.106820, Article 106820
• Main Authors: Dommo, A., Klutse, Nana Ama Browne, Fiedler, Stephanie, Koffi, Hubert Azoda, Vondou, Derbetini A.
• Format: Article
• Language: English
• Subjects: Central Africa; CERES; Cloud radiative effect; CMIP6
• ISSN: 0169-8095
• DOI: 10.1016/j.atmosres.2023.106820

This study investigates the seasonal variability of the cloud radiative effects (CREs) over Congo Basin (CB) using 15-year observations from Clouds and the Earth's Radiant Energy System (CERES) Energy Budget and Filled (EBAF) Ed4.1 level 3b dataset involving CERES and Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on board Terra and Aqua satellites. The relationships between CREs and cloud properties such as total cloud fraction (TCF), cloud top height (CTH), cloud top temperature (CTT) and cloud optical thickness (COT) are checked. An evaluation of Coupled Model Intercomparison Project (CMIP) Phase 6 in capturing the seasonal cycle of CREs as well as the magnitudes of the CREs along the seasonal cycle is also performed. This study shows a net cloud cooling effect of −8.4 W/m2 and − 43.9 W/m2 respectively at the top of the atmosphere (TOA) and at the surface, leading to a net warming effect of 35.67 W/m2 in the atmosphere. This value implies a large energy source over the Central Africa (CA) atmospheric column. The associated relationships between CREs and cloud properties show that the shortwave CRE is more sensitive to TCF and optical thickness whereas its longwave counterparts is more sensitive to CTH, CTT and COT at the TOA and in the atmosphere. All of the four CMIP6 models used in this study can capture the spatial pattern of CREs as well as their seasonal cycle but misrepresent intensity of CREs. Results also show that a better-simulated TCF considerably reduces the intensity of the annual mean underestimation in both longwave and shortwave CRE for some CMIP6 models, but not for models with overestimated shortwave CRE. •Central Africa exhibits a large energy source over its atmospheric column.•The shortwave CRE is more sensitive to total cloud fraction and optical thickness.•A better-simulated total cloud fraction reduces the underestimation in both longwave and shortwave CRE in some CMIP6 models.