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Ideas on Convection Parameterization

Ideas on Convection Parameterization. Almut Gassmann Meteorological Institute, University of Bonn, Germany. What purpose have convection schemes? ->remove instabilities faster than gridscale On which scale are they needed? -> from ~2 km horizontal resolutions and larger

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Ideas on Convection Parameterization

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  1. Ideas on Convection Parameterization Almut Gassmann Meteorological Institute, University of Bonn, Germany

  2. What purpose have convection schemes? ->remove instabilities faster than gridscale On which scale are they needed? -> from ~2 km horizontal resolutions and larger Where are they used? -> operational and climate applications Problem: No-man‘s land of physics -> „go to finer or larger scale“ is an argument, but is not suitable because operational applications use exactly that scale How do convection schemes interact with the dynamics and the gridscale microphysics?

  3. Subsidence Region Updraft and downdraft cores Current assumption Compensating mass fluxes occur in one grid box Grid box Alternative assumption: Compensating mass fluxes occur only partly in one grid box Dynamic model rearranges mass outside the gridbox via pressure gradients. How to determine a? Retriggering of cells by wave effects? Improved resolution independence via the parameter a?

  4. Microphysics interaction? ->Improved and consistent microphysics in the convection scheme. • Downdraft and Sedimentation Same microphysical processes as in microphysics (at least melting and evaporation) Interaction of convectively produced hydrometeors with gridscale scheme in a more direct way (e.g. coalescence) • Lagrangian transport of cells? • Stationarity assumption? Life cycle of cells? • Closure?

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