Spectral microphysics in forecast models with special emphasis on cloud droplet nucleation

• Applicant: Dr. Oswald Knoth
• Subject Area: Atmospheric Science
• Term: from 2004 to 2010
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5426960

The trend in advanced microphysical studies is to combine the dynamics of three-dimensional mesoscale numerical models with the most explicit description of the aerosol/water-drop/ice spectra in a fixed bin-size framework. The detailed treatment of microphysical processes allows to study in detail the microstructure of clouds during their lifetime. Especially one is interested in the role of cloud microstructure in cloud dynamics and the factors who control the variability of drop and ice spectra in space and time and, eventually, the formation and evolution of precipitation. Weather forecast models describe the microphysical processes by a bulk ansatz like the Kessler scheme or more sophisticated two-moments schemes. Therefore, the implementation of a spectral microphysics model within the Local Model (LM) of the German Weather Service is proposed. The development of a forecast model that includes explicit description of the microphysical processes presents a formidable task that must account for many different and complex aspects of the problem. New difficulties arise in the numerical representation of the model's equations and the necessary parallelization of the code. New schemes have to be developed for the model initialization and appropriate boundary conditions. The capabilities of the full scheme will be demonstrated to capture the evolution of precipitating clouds with conditions imposed on aerosol characteristics and flow dynamics.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1167: Quantitative Precipitation Forecast PQP (Praecipitationis Quantitativae Praedictio)
• Participating Persons: Dr. Martin Simmel; Dr. Ralf Wolke