Advances in Geosciences www.adv-geosci.net 1680-7340 1680-7359 17 9th EGU Plinius Conference on Mediterranean Storms (2007) 2008 10.5194/adgeo-17-1-2008 http://www.adv-geosci.net/17/1/2008/ http://www.adv-geosci.net/17/1/2008/adgeo-17-1-2008.html http://www.adv-geosci.net/17/1/2008/adgeo-17-1-2008.pdf 1 4 2008-06-20 Numerical study of two-dimensional moist symmetric instability M. Fantini P. Malguzzi ISAC-CNR, via Gobetti 101, 40129 Bologna, Italy The 2-D version of the non-hydrostatic fully compressible model MOLOCH developed at ISAC-CNR was used in idealized set-up to study the start-up and finite amplitude evolution of symmetric instability. The unstable basic state was designed by numerical integration of the equation which defines saturated equivalent potential vorticity q_e^*. We present the structure and growth rates of the linear modes both for a supersaturated initial state ("super"-linear mode) and for a saturated one ("pseudo"-linear mode) and the modifications induced on the base state by their finite amplitude evolution. Bennetts, D. A. and Hoskins, B. J.: Conditional Symmetric Instability – A Possible Explanation for Frontal Rainbands, Q. J. R. Meteor. Soc., 105, 945–962, 1979. Billet, S. and Toro, E. F.: On WAF-type schemes for multidimensional hyperbolic conservation laws, J. Comput. Phys., 130, 1–24, 1997. Drofa, O. V. and Malguzzi, P.: Parameterisation of microphysical processes in a non-hydrostatic prediction model, in: Proceedings of 14th Intern. Conf. on Clouds and Precipitation (ICCP), Bologna, Italy, 19–23 July 2004, 1297–1300, 2004. Emanuel, K. A.: Observational Evidence of Slantwise Convective Adjustment, Mon. Weather Rev., 116, 1805–1816, 1988 Fantini, M. and Malguzzi, P.: The slope of moist symmetric instability with water loading, J. Atmos. Sci., 68, in press, doi:10.1175/2008JAS2695, 2008. Lindstrom, S. S. and Nordeng, T. E.: Parameterized slantwise convection in a numerical model, Mon. Weather Rev., 120, 742–756, 1992. Kuo, Y.-H. and Reed, R. J.: Numerical simulation of an explosively deepening cyclone in the Eastern Pacific, Mon. Weather Rev., 116, 2081–2105, 1988 Malguzzi, P., Grossi, G., Buzzi, A., Ranzi, R., and Buizza, R.: The 1966 "century" flood in Italy: A meteorological and hydrological revisitation, J. Geophys. Res., 111, D24106, doi:10.1029/2006JD007111, 2006. Nordeng, T. E.: The effect of vertical and slantwise convection on the simulation of polar lows, Tellus, 39A, 354–375, 1987. Schultz, D. M. and Schumacher, P. N.: Use and Misuse of Conditional Symmetric Instability, Mon. Weather Rev., 127, 2709–2732, 1999. Stone, P. H.: On non-geostrophic baroclinic stability, J. Atmos. Sci., 23, 390–400, 1966. Thorpe, A. J. and Rotunno, R.: Nonlinear aspects of symmetric instability, J. Atmos. Sci., 46, 1285–1299, 1989.