HR: 1330h
AN: A22A-1049    [PDF]
TI: Persistent Ice Supersaturation in Tropical Anvil Cirrus
AU: * Jensen, E
EM: ejensen@sky.arc.nasa.gov
AF: NASA Ames Research Center, MS 245-4, Moffett Field, CA 94035 United States
AU: Fridlind, A
EM: fridlind@ice.arc.nasa.gov
AF: NASA Ames Research Center, MS 245-4, Moffett Field, CA 94035 United States
AU: Ackerman, A
EM: ack@fog.arc.nasa.gov
AF: NASA Ames Research Center, MS 245-4, Moffett Field, CA 94035 United States
AU: Pfister, L
EM: pfister@mindego.arc.nasa.gov
AF: NASA Ames Research Center, MS 245-4, Moffett Field, CA 94035 United States
AU: Herman, R
EM: Robert.L.Herman@jpl.nasa.gov
AF: Jet Propulsion Laboratory, Mail Code 183-401 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AU: Bui, T
EM: pbui@mail.arc.nasa.gov
AF: NASA Ames Research Center, MS 245-4, Moffett Field, CA 94035 United States
AU: Baumgardner, D
EM: darrel@servidor.unam.mx
AF: Universidad Nacional Autonoma de Mexico, Centro de Ciencias de la Atmosfera Ciudaad Universitaria, Mexico, DF 04510 Mexico
AU: Lawson, P
EM: plawson@specinc.com
AF: Spec, Inc., Suite B 5401 Western Avenue, Boulder, CO 80301 United States
AB: During the 2002 Cirrus Regional Study of Tropical Anvils and Cirrus Layers - Florida Area Cirrus Experiment (CRYSTAL-FACE), the NASA WB-57 spent many hours sampling cloud microphysical properties, temperature, turbulence, and water vapor concentration within subtropical anvil cirrus. These measurements indicate that air within the cirrus is often substantially supersaturated with respect to ice, with average ice supersaturations increasing from about 5 to 30% as cloud temperature decreases from 220 to 195 K. The persistence of large supersaturations in cirrus with high ice crystal surface areas is unexpected. In this study, we examine the dependence of the measured anvil supersaturations on parameters such as ice water content, turbulence, anvil age, and temperature. We also use a three-dimensional cloud model that resolves the size distributions of cloud particles to investigate the physical processes responsible for the maintenance of ice supersaturation in anvils. The effects of radiatively driven turbulence, wave-driven temperature oscillations, and entrainment of ambient air will be discussed.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0320 Cloud physics and chemistry
DE: 0365 Troposphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting