Advances in Science and Research www.adv-sci-res.net 1992-0628 1992-0636 2 7th EMS Annual Meeting and 8th European Conference on Applications of Meteorology 2007 2008 10.5194/asr-2-133-2008 http://www.adv-sci-res.net/2/133/2008/ http://www.adv-sci-res.net/2/133/2008/asr-2-133-2008.html http://www.adv-sci-res.net/2/133/2008/asr-2-133-2008.pdf 133 138 2008-07-09 Sensitivity experiments of a severe rainfall event in north-western Italy: 17 August 2006 M. Milelli massimo.milelli@arpa.piemonte.it E. Oberto A. Parodi Regional Agency for Environmental Protection – Arpa Piemonte, Torino, Italy CIMA Research Foundation, Savona, Italy This study is embedded into a wider project named "Tackle deficiencies in Quantitative Precipitation Forecast (QPF)'' in the framework of the COSMO (<b>CO</b>nsortium for <b>S</b>mall-scale <b>MO</b>delling) community. In fact QPF is an important purpose of a numerical weather prediction model, for forecasters and customers. Unfortunately, precipitation is also a very difficult parameter to forecast quantitatively. This priority project aims at looking into the COSMO Model deficiencies concerning QPF by running different numerical simulations of various events not correctly predicted by the model. In particular, this work refers to a severe event (moist convection) happened in Piemonte region during summer 2006. On one side the results suggest that details in orography representation have a strong influence on accuracy of QPF. On the other side COSMO Model exhibits a poor sensitivity on changes in numerical and physical settings when measured in terms of QPF improvements. The conclusions, although not too general, give some hint towards the behaviour of the COSMO Model in a typical convective situation. ARPA Piemonte: Rapporto sull'evento meteopluviometrico del 16–18 Agosto 2006, Internal Report, 2006 (in Italian). Bechtold, P., Bazile, E., Guichard, F., Mascart, P., and Richard, E.: A mass flux convection scheme for regional and global models, Q. J. Roy. Meteor. Soc., 127, 869–886, 2001. Davies, H. C.: A lateral boundary formulation for multi-level prediction models, Q. J. Roy. Meteor. Soc., 102, 405–418, 1976. Davies, H. C.: Limitations of some common lateral boundary schemes used in regional NWP models, Mon. Weather Rev., 111, 1002–1012, 1983. Dierer, S., Arpagaus, M., Damrath, U., Seifert, A., Achimowicz, J., Avgoustoglou, E., Andreadis, T., Baldauf, M., Dumitrache, R., Fragkouli, V., Grazzini, F., Louka, P., Mercogliano, P., Mezzasalma, P., Milelli, M., Mironov, D., Morgillo, A., Oberto, E., Parodi, A., Pescaru, I. V., Pflueger, U., Schubiger, F., Starosta, K., and Tesini, M. S.: Final report of the COSMO priority project "Tackle deficiencies in quantitative precipitation forecasts", COSMO Internal Report, 1–47, 2007. Doms, G. and Schättler, U.: A description of the non-hydrostatic regional model LM. Part I: Dynamics and Numerics, http://www.cosmo-model.org/content/model/documentation/core/default.htm, 1–140, November 2002. Kain, J. S. and Fritsch, J. M.: A one-dimensional entraining/detraining plume model and its application in convective parameterization, J. Atmos. Sci., 47, 2784–2802, 1990. Kain, J. S. and Fritsch, J. M.: Convective parameterization for mesoscale models: The Kain-Fritsch scheme. The representation of cumulus convection in numerical models, Meteor. Monogr., 27, Amer. Meteor. Soc., 165–170, 1993. Lin, Y. L., Chiao, S., Wang, T., Kaplan, M., and Weglarz, R.: Some Common Ingredients for Heavy Orographic Rainfall, Weather Forecast., 16(6), 633–660, 2001. Lindborg, E.: Can the atmospheric kinetic energy spectrum be explained by two-dimensional turbulence?, J. Fluid Mech., 388, 259–288, 1999. Mellor, G. L. and T. Yamada, T.: A hierarchy of turbulence closure models for planetary boundary layers, J. Atmos. Sci., 31, 1791–1806, 1974. Milelli, M., Oberto, E., and Parodi, A.: Proscenium Project official report, 1–24, 2007. Rudari, R., Entekhabi, D., and Roth, G.: Terrain and Multiple Scale Interactions as Factors in Generating Extreme Precipitation Events., J. Atmos. Sci., 5(3), 390–404, 2004. Skamarock, W. C. and Klemp, J. B.: The Stability of Time-Split Numerical Methods for the Hydrostatic and the Nonhydrostatic Elastic Equations, Mon. Weather Rev., 120, 2109–2127, 1992. Skamarock, W. C.: Evaluating Mesoscale NWP Models Using Kinetic Energy Spectra, Mon. Weather Rev., 132, 3019–3032, 2004. Steppeler, J., Doms, G., Schaettler, U., Bitzer, H. W., Gassmann, A., Damrath, U., and Gregoric, G.: Meso-gamma scale forecasts using the non-hydrostatic model LM, Meteorol. Atmos. Phys., 82, 75–96, 2003. Tiedtke, M.: A comprehensive mass flux scheme for cumulus parametrization in large-scale models, Mon. Weather Rev., 117, 1779–1800, 1989.