HR: 0800h
AN: A21B-0738    [Abstracts]
TI: Cross-tropopause Transport by Deep Convection and Its Implications to Climate and Atmospheric Chemistry
AU: * Wang, P K
EM: pao@windy.aos.wisc.edu
AF: University of Wisconsin-Madison, Department of Atmospheric and Oceanic Sciences 1225 W. Dayton Street, Madison, WI 53706 United States
AB: Recent observations by aircraft and meteorological satellites (such as GOES, AVHRR, POAM and MODIS) have indicated unambiguous signature of cross-tropopause transport by deep convective systems. These include cirrus plumes located a few kilometers above the anvils of severe storms as shown by satellite visible and infrared images, measurements of trace gases of tropospheric origin in the lower stratosphere in the outflow region of deep convection, and satellite observations of tropopause penetration of ashes by boreal fire-induced storms. We have performed numerical simulations of the anvil top plumes above severe storms and the fire-induced storms using a 3-D nonhydrostatic cloud model. The simulated plumes and pyrocumulonimbus resemble those observed. Analyses of simulation results show that the irreversible mass transfer through the tropopause is mainly due to the diabatic turbulent diffusion induced by the breaking of gravity waves caused by the deep convection. The same mechanism also explains the controversial "jumping cirrus" phenomenon reported by Ted Fujita in 1980s. Such irreversible mass transfer of water vapor and other chemical species from the troposphere to the lower stratosphere would have significant implications on the global climate and atmospheric chemistry. It is also likely that we need to revise our understanding of the global stratosphere-troposphere exchange process substantially in light of these new observations. A summary of the recent observations and model simulations and discussions on their implications on climate, atmospheric chemistry, and global transport process will be presented in the meeting.
DE: 3334 Middle atmosphere dynamics (0341, 0342)
DE: 3362 Stratosphere/troposphere interactions
DE: 0340 Middle atmosphere--composition and chemistry
DE: 0341 Middle atmosphere--constituent transport and chemistry (3334)
DE: 0342 Middle atmosphere--energy deposition
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting