Characterizing the evolution of the radiative forcing of shallow and deep convective clouds throughout their life cycle by combining airborne and satellite observations in the tropical Atlantic Ocean

• Applicant: Dr. André Ehrlich
• Subject Area: Atmospheric Science
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 502188551

Over the tropical oceans, shallow trade-wind cumuli and deep convective clouds have been identified as major contributors to the atmospheric radiative energy budget. Accurately characterizing these clouds and quantifying their radiative impact based on their properties remains important for the improvement and validation of the radiative energy budget in numerical weather prediction and global climate models. For trade-wind cumuli, airborne and satellite observations from the EUREC4A campaign in 2020 assessed whether the macrophysical or microphysical properties of the clouds were the main driver of the cloud radiative forcing. The project seeks to extend this study by considering the life cycle of convective clouds. In addition to shallow cumulus, deep convective clouds within and at the edge of the Atlantic ITCZ will be analysed. The core objective is to quantify the changes in the radiative forcing of these two cloud regimes during their life cycle as a function of the evolution of the cloud macrophysical and microphysical properties and to test the hypothesis that cloud macrophysical properties dominate the cloud radiative forcing in the early stages of the cloud lifetime, whereas microphysical properties become more important in mature stages. To achieve this objective, we make use of the airborne observations during the HALO mission, EC-TOOC. Combining high temporally and spatially resolved airborne observations with the broader, continuous overview of satellites, we aim to capture a comprehensive depiction of clouds as they develop over the course of several hours. The cloud properties of interest include cloud fraction, cloud top altitude, liquid water path, cloud particle radius, the two-dimensional spatial organization of the cloud field, the heterogeneity of the cloud field, cloud particle phase, as well as sea surface temperature and thermodynamic and aerosol conditions. To study the cloud evolution, state of the art cloud tracking methods will be applied. By retrieving an estimate of the cloud lifetime and stage of development, a new parameter will be available and extend previous studies. The relation between macrophysics or microphysics and cloud radiative forcing derived for deep convective clouds will be compared to shallow clouds in the trade-wind region. Differences due to aerosol and thermodynamic conditions will be explored.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1294: Atmospheric and Earth System Research with the "High Altitude and Long Range Research Aircraft" (HALO)
• Co-Investigator: Professor Dr. Manfred Wendisch