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Alex Hoffmann MSc

PhD Student

Current research interests focus on the influence of mesoscale and microscale diabatic processes (including surface-atmosphere and aerosol-cloud interactions) on mesoscale atmospheric weather systems, in particular on their influence on island (deep) convection and storm dynamics over the Tiwi Islands, Australia, and the Easter Island, Chile, through a combined model development, numerical simulations and observations approach

Biography

Career

Qualifications

Research

Member, Cambridge Centre for Climate Science and Centre for Atmospheric Science.

Clouds, atmospheric water vapour and aerosols constitute a major source of uncertainties in climate predictions, principally because of the uncertainty regarding the global distribution of cloud ensembles that occurs as a response to higher surface temperatures, the interactions between aerosols and clouds, and their feedback on the energy budget and global circulation patterns. Clouds are also a major weather forecasting issue, due to their role in the formation of precipitation and corresponding questions about water resources availability, the production of severe weather events and aviation safety. Even if several basic processes concerning cloud formation and evolution are well established, many fundamental issues related to the understanding of real clouds and their temporal and spatial evolution remain unsolved.

The non-hydrostatic Active Tracer High-resolution Atmospheric Model (ATHAM) is a cloud-resolving model that had initially been designed for the simulation of explosive volcanic plumes, and later been applied to investigations in a number of other events characterized by convective forcings. In the framework of this project, ATHAM has been extended with a new parallelized model output facility (PnetCDF), and with an in-house vegetation dynamics model (HYBRID) and a well-established bulk sea surface flux algorithm (COARE), to capture turbulent boundary layer fluxes of energy and matter between surface and atmosphere. In-depth testing of this new model configuration has been performed (on High Performance Computing clusters) for a scenario over the Tiwi Islands with investigations into Hector storm triggering, evolution and decay, with emphasis on the organization and formation of structure in shallow boundary layer convection preceding the actual storm. ATHAM will now be set into the context of hypothetical human-induced deforestation over Rapa Nui (Easter Island), to investigate the influence of land cover change on the partitioning of surface fluxes into sensible and latent heat, and hence, ultimately, onto the hydrological cycle of the island.

Simulations are compared to and initialized from remote sensing observations and/or in situ measurements. Model output can now be converted into Earth Observation (lidar/radar/passive RS) space by using a new interface to the CFMIP Observation Simulator Package (COSP). Some emphasis of this work is on advanced data visualization and analysis techniques for a more straightforward and in-depth interpretation of simulated phenomena.

In short, my current research shall primarily

Along the mesoscale modelling work, I am also involved in the mission analysis and preliminary feasibility study of a novel space mission concept for upper air water vapour active remote sensing, a project spun off a summer school.

My work is funded through the Fonds National de la Recherche (Luxembourg) and the Cambridge European Trust/NERC (UK), and a number of smaller grants and awards.

Publications

Selected publications

Conferences, talks and courses

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External activities