HR: 09:15h
AN: A11B-06    [PDF]
TI: The Microphysical and Radiative Evolution of a Cirrus Anvil During CRYSTAL-FACE
AU: * Navarro, B C
EM: bnavarro@met.utah.edu
AF: Meteorology Department University of Utah, 135 S 1460 E Rm 819, Salt Lake City, UT 84112 United States
AU: Garrett, T J
EM: tgarrett@met.utah.edu
AF: Meteorology Department University of Utah, 135 S 1460 E Rm 819, Salt Lake City, UT 84112 United States
AU: Baumgardner, D
EM: darrel@servidor.unam.mx
AF: Universidad Ciencias de la Atmosfera, Ciudad Univeristaria, Mexico City, 04150 Mexico
AU: Bui, P
EM: pbuli@mail.arc.nasa.gov
AF: NASA, NASA Ames Research Center, Moffett Field, 94035 United States
AU: Gerber, H
EM: hgerber6@comcast.net
AF: Gerber Scientific Inc, 1643 Bentana Way, Reston, VA 20190 United States
AU: Heymsfield, A
EM: heyms1@ucar.edu
AF: NCAR, MMM Division 3450 Mitchell Lane, Boulder, CO 80301 United States
AU: Lawson, P
EM: plawson@specinc.com
AF: SPEC Inc, 3022 Sterling Circle, Suite 200, Boulder, CO 80301 United States
AU: Minnis, P
EM: p.minnis@larc.nasa.gov
AF: NASA Langley Research Center, Mail Stop 420, Hampton, VA 23681-2199 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
AU: Twohy, C
EM: twohy@coas.oregonstate.edu
AF: Oregon State University, College of Atmospheric and Atmospheric Sciences Oceanography Admin 104, Corvallis, OR 97331 United States
AU: Weinstock, E
EM: weinstock@huarp.harvard.edu
AF: Harvard University, Atmospheric Research Project 12 Oxford St, Cambridge, MA 02138 United States
AU: Herman, R
EM: robert.l.herman@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Ave, Pasadena, CA 91109 United States
AB: A case study of the evolution of a thunderstorm cirrus anvil measured during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) is presented. In situ measurements of cloud bulk properties and size spectra were obtained using the NASA WB-57F and the University of North Dakota Citation aircraft. The cirrus anvil contained bulk ice water contents up to 0.30 g m$^{-3}$ at one hour age, diminishing to 0.018 g m$^{-3}$ at 2.5 hours of age. Ice crystal size distributions were bi-modal, with the largest crystals and effective radii near the base of the anvil. At one hour age, the optical depth calculated from in situ bulk visible extinction coefficient measurements was $\sim$21.7. Ice water content, total ice crystal concentration, relative humidity with respect to ice, and effective radius all decreased with increasing distance from the upwind edge of the anvil. The effective radius was dominated primarily by small ice crystals with a mode size of 25 $\mu$m. The anvil's microphysical evolution depended primarily on dilution by entrainment, and to a lesser degree on sedimentation of large ice crystals. A second, thinner cloud, with an optical depth of 0.4, existed about 1.5 km above the anvil at the tropopause at an altitude of about 13.0 to 14.5 km and at temperatures as cold as $-70\deg$C. The cloud appears to be a remnant of the initial convective impulse of the anvil, which then maintained itself through internal circulations as the anvil dissipated beneath it. Size distributions in this cloud were mono-modal with bulk ice water content values generally below 0.0015 g m$^{-3}$. The stability of this cloud suggests a possible production mechanism for the subvisible cirrus widespread over tropical regions.
DE: 0320 Cloud physics and chemistry
DE: 0360 Transmission and scattering of radiation
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting