Tuesday, 11 January 2005
Coupling sub-grid scale moist convection with global dynamics
Horizontal resolution of O(1) km is required to resolve precipitating deep convection in the Earth atmosphere. Using the best numerical techniques and solvers currently available, climate simulations using a convection-resolving global model require Petaflops execution rates due to the number of degrees of freedom and the restrictive time-step size. Given the current rate of advance in computer performance, 2010 is the earliest date that such resources will become available. A promising alternative to such a model is to couple a scalable and efficient dynamical core with the cloud-resolving convection parameterization (CRCP). The idea behind CRCP is to replace a column-based sub-grid scale convective parameterization with a 2D anelastic cloud resolving model. Such an approach, also referred to as the "super-parameterization", allows not only for trustworthy representation of convective dynamics, but also for coupling among all essential small-scale processes, such as cloud microphysics, radiation, land surface, boundary layer, etc. In this work, the dynamical core is the 3D spectral element model developed at NCAR. We validate the effort by simulating coherent structures, similar to the Madden-Julian Oscillation (MJO) observed in the Earth's tropics. The simulations are based on the simplified constant sea-surface temperature (SST) aqua-planet, equivalent in size to Earth and with the same rotational rate, in radiative-convective quasi-equilibrium. Preliminary results from aqua-planet simulations applying realistic meridional SST distributions will also be presented.