MSCCC · Marine Stratocumulus Cloud Cover and Climate

Marine Stratocumulus Cloud Cover and Climate

Global climate change is forced by the balance of the warming due to anthropogenic greenhouse gases and the cooling due to anthropogenic aerosol pollution particles. Among these, the cloud-mediated aerosol radiative forcing is by far the main component of the uncertainty. Marine Stratocumulus Clouds (MSC) play a decisive role in the climate system due to their very large net effect on the Earth's radiative energy budget. The two main cloud regimes of MSC are open and closed cells. The less cloudy open cells are leaving much of the dark ocean unobscured, while the fully cloudy closed cells in turn are causing a very large cloud radiative effect in the solar radiation spectrum. Anthropogenic perturbation such as CO2 warming, but in particular also anthropogenic aerosol pollution, may delay the transition between open and closed cell regimes. The main hypothesis of the Marine Stratocumulus Cloud Cover and Climate (MSCCC) is that anthropogenic aerosols exert a substantial radiative forcing via their potential to impede or delay the transition from closed to open cells regime. This hypothesis was addresses via analysis of observational data and model simulations of different scales. The objectives of the study were (1) developing novel methodologies for satellite retrievals of properties related to marine stratocumulus clouds, (2) to employ the developed methodologies to seek an in-depth understanding of the processes relevant for the transition between marine stratocumulus cloud cover regimes, (3) to test global climate model parameterizations responsible for marine stratocumulus cloud cover changes, (4) to quantify the contribution of the delay in marine stratocumulus transitions to the climate forcing, and (5) to obtain new skills and knowledge in climate modelling, gain scientific and public recognition of my work, and gather experience in teaching and student mentoring. The results and insights from MSCCC are of immediate relevance to society via improved physical understanding that leads to a more reliable projections of future climate change. The results further are highly relevant to the research on climate geo-engineering via marine cloud brightening, although it remains an open question whether this may be considered beneficial for society.

Data: CORDIS, © European Union