HR: 08:45h
AN: A11D-04    [PDF]
TI: Effect of Convective Parameterization Closure on Climate Simulation in the NCAR Model
AU: * Zhang, G J
EM: gzhang@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr., La Jolla, CA 92093-0221 United States
AB: This paper investigates the role of convective parameterization closures in the NCAR CCM3 climate simulation. Several recent observational studies using both tropical and midlatitude data suggest that the conventional convective instability-based closures for convective parameterization can deviate considerably from reality, particularly at sub-daily timescales. Based on these studies, a new closure for convective parameterization is devised. It is implemented and tested in the NCAR GCM. Results from the test simulations show that there is significant improvement in the simulated model climate. For example, the seasonal variation of tropical precipitation is in better agreement with the observations. Many GCMs including the NCAR model and the ECMWF model have difficulties in simulating the diurnal cycle of convection correctly. Particularly over land, the simulated convection occurs too early compared to observations. We will show that with the new closure, the simulated diurnal cycle of convection over land is much closer to what is observed.
DE: 3300 METEOROLOGY AND ATMOSPHERIC DYNAMICS
DE: 3314 Convective processes
DE: 3319 General circulation
DE: 3374 Tropical meteorology
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting