An interdisciplinary project for investigating secondary particle production by large hydrometeors inside atmospheric clouds: a study on activation of cloud aerosols (Activation of Aerosols: ActivAero).

• Applicant: Dr. Taraprasad Bhowmick
• Subject Area: Atmospheric Science ; Geophysics ; Fluid Mechanics
• Term: from 2021 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 463393443

Weather forecasting models suffer from our limited knowledge of the interconnected physical and chemical processes over the wide scales of clouds, which remain a source of uncertainty in climate science and atmospheric circulation. Secondary particle production is such a process, which actively controls the life cycle of clouds, their radiative properties and hydrological fluxes and contributes to the broadening of particle size through collisions, but is still not well understood. This proposed Walter Benjamin project aims to parameterize the impact of such a secondary particle production process on the life cycle of clouds, which is the activation of aerosols in the supersaturated wake of large precipitating hydrometers. This project is timely as recent laboratory experiments on precipitating cloud droplets observed an activation of the surrounding aerosol population in the wake of the large warmer cloud droplets (Prabhakaran et al. (2020)). To obtain a global picture on the impact of this secondary aerosol activation process, I propose to conduct a rigorously intensive numerical investigation with 1) a fully two-way coupled dynamic and thermodynamic direct numerical simulation together with 2) a model for turbulence in the clouds. 3) Lagrangian tracking of cloud aerosols together with 4) a microphysical model for aerosol growth will be used to parameterize the impact of wake-induce aerosol activation on the cloud life cycle. This project will develop a novel interdisciplinary knowledge base with a comprehensive and integral incorporation of different interconnected physical and chemical processes contributing to this aerosol activation process, that were not considered so far. The implementation of the specific objectives of this project requires a multidisciplinary training for me in the scientific fields of cloud microphysics, fluid dynamics, numerical simulations, aerosol chemistry, etc. This project also requires an integration of the numerical investigation with the data of the field and laboratory cloud experiments. This project will not only improve my future career prospects to become an independent researcher and future group leader in the field of geophysical fluid dynamics and cloud physics, but also will generate an integrated knowledge of the topic, which will have multidisciplinary implications. This project will address the knowledge gap on the interplay between cloud physics, transfer processes and microphysical evolution of hydrometeors, and the parameterized activation rate would be relevant for fine tuning the regional and global climate and weather models, and thus contribute to the Sustainable Development Goal 13: Climate Action.

• DFG Programme: WBP Position