HR: 0810h
AN: A51F-02    [Abstracts]
TI: Simulations of Madden-Julian Oscillations with the Reduce Acceleration in the VErtical (RAVE) approach
AU: * Kuang, Z
EM: kuang@fas.harvard.edu
AF: Department of Earth and Planetary Sciences and School of Engineering and Applied Sciences, Harvard University, 20 Oxford St., Cambridge, MA 02138, United States
AU: Walker, C
EM: cwalker@fas.harvard.edu
AF: Department of Earth and Planetary Sciences and School of Engineering and Applied Sciences, Harvard University, 20 Oxford St., Cambridge, MA 02138, United States
AB: The Madden-Julian Oscillation (MJO) is a dominant mode of tropical intra-seasonal variability and has far- reaching influences within and beyond the tropics. Despite numerous studies, its mechanism is still not well understood and General Circulation Models in general do not simulate MJO well. In this talk, we present results from near-global simulations using the Reduced Acceleration in the VErtical (RAVE) approach (Kuang et al. 2005). The Weather Research and Forecasting (WRF) model is modified for this purpose and is forced with realistic surface boundary conditions and run with a horizontal resolution of ~80km. The simulated precipitation patterns in general agree with the observed ones, except that during northern hemisphere summer, there is excessive precipitation over western Pacific associated with the Southeast Asian monsoon, similar to that seen in simulations using the superparameterization approach (Khairoutdinov et al., 2005). The simulated spectra compare favorably with the observations, so do the spatial distribution of the MJO-filtered variance and the MJO composite structures. A simulation at the same resolution but without using the RAVE approach did not produce realistic MJOs. On the other hand, reasonable simulations of MJO were obtained with a 160-km horizontal resolution using the RAVE approach, which appears to be a relatively inexpensive way to simulate and study MJOs. Reference: Kuang, Z, P. N. Blossey, C. S. Bretherton, A new approach for 3D cloud resolving simulations of large scale atmospheric circulation, Geophys. Res. Letts., Vol. 32, No. 2, L02809, 10.1029/2004GL021024, (2005). Khairoutdinov M., D. Randall, C. DeMott, Simulations of the atmospheric general circulation using a cloud- resolving model as a superparameterization of physical processes, J. Atmos. Sci., 62, 2136-2154, (2005).
DE: 3314 Convective processes
DE: 3337 Global climate models (1626, 4928)
DE: 3374 Tropical meteorology
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting