Object-based characterization of continental Shallow Cumulus using synergistic decameter-scale observations

Résumé fourni par la source

Shallow convective cumulus clouds (ShCu) play a crucial role in weather and the global climate system. These clouds are characterized by spatial and temporal variability on a wide range of scales, making ShCu an important contributor to the uncertainty in determining the local and global radiation budget as well as mass transport. Since individual remote sensing instruments can only capture a small part of this variability, a synergy of several observations is beneficial. By combining very high spatial resolution, multispectral observations from the polar-orbiting Sentinel-2 satellite with a stereo camera-based 4D cloud product, Clouds Optically Gridded by Stereo (COGS), we will analyze 15 scenes of continental ShCu in a 6x6x6km3 domain around the Central Facility of the ARM Southern Great Plains site in the United States. Using an object-based approach, we will highlight the three-dimensional geometric properties of individual ShCu and the relationship to their multispectral reflectances and their cloud shadows. The meteorological influences on the geometric properties, and the relationship between cloud size, cloud thickness and cloud volume will be discussed. Furthermore, considering the 270km wide observation path of the Sentinel-2 satellite, we will discuss the influence of cloud geometry, meteorological conditions and the organization of ShCu on the variability of cloud fraction and cloud size distributions, as an important step towards the parameterization of ShCu in climate models. The results will also be placed in the context of temporal cloud development.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.