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Abstract:
Interactions between aerosols and clouds, as well as their radiative consequences, have been a long-standing problem to understand cloud physics as well as anthropogenic impacts on climate. Satellite-based investigations of the direct and indirect impact of aerosols on liquid clouds have led, during the last decade, to significant progress in the understanding and quantification of such processes. This study makes use of a recent product of the ice crystal number concentration (Nice), obtained from combined liDAR-raDAR (DARDAR) measurements. This product provided the first global distribution of Nice from satellite and has been now extensively used for model evaluation and to provide context to in-situ data. In this study, we use this project co-jointly with collocated aerosol information from the Copernicus Atmospheric Monitoring Service (CAMS) reanalyses to investigate the global impact of aerosols on Nice. A multitude of cloud regimes, subdivided into seasonal and regional bins, are considered to disentangle meteorological effects from the aci signature. First results of joint-histograms between Ni and the aerosol mass show an overall positive sensitivity of Ni to the aerosols load. We find that this sensitivty is particularly strong towards to cloud-top and flattens towards cloud-base, consistently with expectations for homogeneous nucleation processes. The response of the ice water content, in terms of adjustment to the initial aerosol perturbation as also quantified. Finally, the effective radiative forcing associated with aerosol - ice cloud interactions will be quantified. Despite being small compared to that of liquid clouds, its sign depends on the considered cloud regime.
