Investigating the impact of Land-use and land-cover change on Aerosol-Cloud-precipitation interactions Using Polarimetric Radar retrievals (ILACPR)

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Project ILACPR contributes to objective one of a priority programme, the exploitation of radar polarimetry for quantitative process and model evaluation, and provides new insights on the impact of anthropogenic land-use and land-cover changes on cloud microphysical and macrophysical (dynamical) mechanisms. Preliminary numerical modeling study of summertime convective storm with large-scale perturbation of aerosols and change in land-cover suggests that the response of the system in terms of surface precipitation to the forcing is weak. However, the microphysical/macrophysical pathways acting as a buffered system to the changes in forcing, differs. Polarimetric radar measurements in combination with such numerical model scenarios allow investigation of the buffering mechanisms, arising from interactions between land, aerosols, clouds and precipitation processes. Polarimetry enables us to study the evolution of the microphysical and macrophysical processes for simulated as well as observed precipitating clouds. The sketches of modified precipitation generating processes in terms of polarimetric fingerprints enables us to validate the results from the numerical model scenarios and represent the feedback processes between the surface flux partitioning and aerosol-cloud interactions. The Terrestrial Systems Modeling Platform (TerrSysMP) will be used to investigate the impact of land-use/land-cover change on aerosol distributions and land-aerosol-cloud-precipitation interactions. While the atmospheric model in TerrSysMP currently ignores the variability and feedbacks of land-cover, atmospheric chemistry and aerosols, the model will be extended with a chemical transport model (CTM) to allow for the quantitative investigation of land-aerosol-cloud-precipitation interaction.Multiple ensemble simulations over diurnal scales with different meteorological settings will be conducted with TerrSysMP and TerrSyMP-CTM over the northwestern part of Germany, bordering Netherlands, Belgium, Luxemburg and France. The common analysis of observed and synthetic (model generated) polarimetric fingerprints for microphysical and macrophysical processes, like evaporation, riming / aggregations, and updraft-downdraft intensities based on different model scenarios with and without CTM represents a new promising strategy to understand the impact of anthropogenic land-use and land-cover changes on the evolution of precipitation generating systems.