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FRINATEK-Fri prosj.st. mat.,naturv.,tek

Planetary Boundary Layer Feedback in the Earths Climate System

Tildelt: kr 5,1 mill.

The lower atmosphere and the upper ocean are turbulent or chaotic. The turbulence transports heat, moisture/aerosols from the surface, where solar radiation is absorbed and moisture/pollution fluxes are originated, to the atmosphere. For 50 years, turbule nt mixing has been recognized as one of the most important dynamical processes in the Earth Climate System. Nevertheless, its representation in models suffers from major deficiencies. The turbulent mixing in stratified flows, such as the atmospheric plane tary boundary layer (PBL), was poorly understood. It was overlooked that existing approaches to the turbulent mixing break down the energy conservation. Recent joint advance in the turbulence theory, turbulence-resolving modeling and remote sensing have r esulted in recovery of the total turbulence energy conservation law. The project utilizes theoretical, numerical and observational progress to narrow uncertainties in our knowledge of the Climate System. Its focus is a PBL-feedback - effects of changes in the turbulent mixing on temperature and its variability. The turbulent mixing is a non-linear dynamical process, which climate models do not resolve. This is the major challenge. Theory guides, the PBL depth, H, is a measure of the turbulent mixing. H is poorly defined quantity in observations. The challenge is to improve knowledge and retrieval of this quantity assimilating data into turbulence-resolving models. Besides climatology, the accurate PBL depth is required by. The project capitalizes on a sim ple prediction - the PBL-feedback is the largest where H is the smallest; and on non-trivial prediction - multi-regime behavior in the cold PBL as sudden temperature rise/drop. The predictions point out on cold and/or arid climates, which motivates the em phasis on the Arctic and adjacent areas. It is expected to improve knowledge of the Arctic climatology and causes of the polar amplification of global warming, and to investigate links to abrupt climate changes.

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FRINATEK-Fri prosj.st. mat.,naturv.,tek