HR: 11:35h
AN: A11H-06    [PDF]
TI: Drying and moistening by deep sub-tropical and tropical convection in large-eddy simulations of CRYSTAL-FACE and CEPEX field measurements
AU: * Ackerman, A S
EM: andrew.ackerman@nasa.gov
AF: NASA ARC, address, Moffett Field, CA 94035 United States
AU: Fridlind, F M
EM: ann.fridlind@nasa.gov
AF: NASA ARC, address, Moffett Field, CA 94035 United States
AU: Jensen, E J
EM: eric.j.jensen@nasa.gov
AF: NASA ARC, address, Moffett Field, CA 94035 United States
AU: Stevens, D E
EM: dstevens@llnl.gov
AF: LLNL, address, Livermore, CA 94551 United States
AU: Miloshevich, L M
EM: milo@ucar.edu
AF: NCAR, address, Boulder, CO 80307 United States
AU: Baumgardner, D
EM: plawson@specinc.com
AF: UNAM, address, Mexico, DF 04150 Mexico
AU: Lawson, P
AF: SPEC, Inc, address, Boulder, CO 80301 United States
AB: Deep convection has been proposed to be a leading mechanism controlling the moisture in the lower stratosphere. We evaluate this hypothesis with large-eddy simulations that resolve the size distributions of aerosols and cloud particles over 100-km square square domain using pre-convective Miami and PARSL soundings, initiating convection with enough of a surface heat source to match the observed anvil altitudes. Differencing the moisture field after the anvils decay with the initial state, we find that convection predominantly moistens the transitional tropopause layer (TTL), although some drying is predicted in localized layers. Beyond the sub-tropical convection of Florida we also use frostpoint hygrometer soundings obtained during the CEPEX mission in the tropical western Pacific, which show repeated evidence of supersaturated layers within the TTL. In such cases we find that deep convection dries out the supersaturated layers while moistening the air above and below. We also analyze the environmental and temporal dependence of the time constants of sedimentation, evaporation, and mixing of water.
DE: 0320 Cloud physics and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting