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Characteristics of Mesoscale Extremes in the Extratropical Troposphere

Christ Weijenborg, Petra Friederichs and Andreas Hense, Meteorological Institute and IZKS, University of Bonn

Mesoscale weather forecasts are generated using limited area numerical weather prediction (NWP) models on fine grids that are embedded within coarse global models. The German Weather Service (DWD) employs the COSMO-DE model, which is a state of the art convection resolving version of the Consortium for Small-Scale Modeling (COSMO) limited area model. It is particularly developed to predict high impact weather over Germany and adjacent areas, and to provide probabilities of extreme weather for early warning systems.

The ensemble prediction system (EPS) based on COSMO-DE lies at the core of this project.  In the project parts led by the Bonn group, we will study the statistics and dynamics of the COSMO-DE EPS, in a quest for an improved understanding of the physics of mesoscale weather extremes and their spatio-temporal characteristics. The general hypothesis to be tested is that mixing processes of conserved quantities by organized and/or turbulent circulation manifest themselves in the observed extremes. The generation of mesoscale extremes will be investigated in terms of the three-dimensional Ertel's potential vorticity.


Bierdel, L., P. Friederichs and S. Bentzien (2012): Spatial kinetic energy spectra in the convection-permitting limited area NWP model COSMOS-DE. Meteorol. Z. 21,doi: 10.1127/0941-2948/2012/0319

Weijenborg, C., P. Friederichs, and A. Hense (2014): Organisation of potential vorticity during severe convection. (submitted to Tellus A)