HR: 1330h
AN: A22A-1052    [PDF]
TI: Small Scale Motions in Anvils During the CRYSTAL Florida Area Cirrus Experiment
AU: * Pfister, L
EM: lpfister@mail.arc.nasa.gov
AF: NASA/Ames Research Center, Atmospheric Chemistry and Dynamics Branch, MS 245-5, Moffett Field, CA 94035-1000 United States
AU: Bui, P
EM: pbui@mail.arc.nasa.gov
AF: NASA/Ames Research Center, Atmospheric Chemistry and Dynamics Branch, MS 245-5, Moffett Field, CA 94035-1000 United States
AU: Poellot, M
EM: poellot@aero.und.edu
AF: University of North Dakota, Department of Atmospheric Sciences, Box 9006, Grand Forks, ND 58202 United States
AB: Small scale motions in cumulus anvils are important because of their potential ability to transport heat, momentum, moisture, and ice. Also, the speed with which the turbulence decays may have an impact on the lifetime of ice particles. Finally, the strength of the small scale motions is an indication of how high the resolution of anvil models must be. The approach is to examine the vertical and horizontal velocity spectra, and vertical heat fluxes from anvil passes between 10-15 km during CRYSTAL-FACE from WB-57 and Citation aircraft. These can be compared with spectra from passes through major convective updrafts performed by a DC-8 aircraft during a different Florida convection experiment. Results for the WB-57 measurements show that: (1) small scale motions decay rapidly in the Florida anvils, the maximum power decaying by .5-1 decade per hour as the anvil ages; (2) spectra are quite steep in the anvil, with power decaying according to a -3 power law, in contrast to regions near the updraft where the power law is closer to -5/3; and (3) heat fluxes are mostly negative near the anvil tops, in contrast to the positive heat fluxes found during the active updrafts. The last result probably reflects the action of the turbulence in transporting air above the anvil (which has a substantially higher potential temperature than anvil air) downward into the anvil. Further work to be presented includes comparison with data from the Citation aircraft.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0320 Cloud physics and chemistry
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting