92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Wednesday, 25 January 2012: 8:45 AM
Tropical Cyclones and Other Mesoscale Phenomena in 25 Km CAM Simulations
Room 355 (New Orleans Convention Center )
Julio T. Bacmeister, NCAR, Boulder, CO; and C. Hannay, R. B. Neale, and J. E. Truesdale

Results from global high-resolution (0.23x0.31 degree) simulations using CAM4 and CAM5 are presented. CAM4 and CAM5 differ in their parameterizations of many physical processes that are expected to play an important role in tropical cyclone dynamics, including planetary boundary layer transport, shallow convection, and cloud microphysics.However they use the same deep convection scheme. Analysis of an extended 20-year forced-SST, CAM4 run reveals a climatology of tropical cyclones that is reasonable in many respects, although somewhat underactive in overall storm numbers for several basins. We compare the behavior of CAM4 and CAM5 during selected overlap periods in 2004-2006. Tropical cyclogenesis in CAM5 appears to be significantly more active during these periods. We explore possible causes for these differences, and also examine the sensitivity of CAM5 simulations to changes in precipitation physics. We will also present preliminary results on other explicitly resolved mesoscale phenomena in the simulations such as gravity waves and propagating convective systems.

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