HR: 09:30h
AN: A11B-07    [PDF]
TI: Relationship Between Cirrus Anvil ice Crystal Properties and Aerosol Concentration, Ambient Relative Humidity and Vertical Velocity During CRYSTAL FACE
AU: * Andronache, C
EM: andronac@bc.edu
AF: Boston College, Gasson Hall 012, 140 Commonwealth Ave, Chestnut Hill, MA 02467 United States
AU: Phillips, V
EM: Vaughan.Phillips@noaa.gov
AF: Princeton University, NOAA/GFDL, Forrestal Campus Rte. 1, PO BOX 308, Princeton, NJ 08542 United States
AB: The coverage of cirrus in the tropics and their radiative effects depend on anvil lifetimes and spreading in the upper troposphere (UT). One of the goals of the CRYSTAL FACE (CF) experiment is to understand the cirrus anvil evolution processes. Cirrus anvil properties can be linked to intensity of convection in the generating cumulonimbus and on UT ambient conditions. This work uses CF measurements to document the dependence of cirrus anvil ice crystal concentration and effective size on aerosol concentration, ambient relative humidity and vertical velocity. It is shown that the presence of significant ice crystal concentration (diameter larger than 50 micrometers) in cirrus anvil is linked to ambient water vapor supersaturated with respect to ice, predominant mesoscale updraft motion and large number concentration of aerosol particles (with diameter less than 1 micrometer). The study presents cases with time evolution of anvil characteristics and a discussion of factors that affect aerosol and ice crystal concentration during cirrus anvil aging. With the aim of diagnosing the dependence of ice crystal concentration on vertical motion in the cumulonimbus core, and possible dependence on atmospheric aerosol loading, an explicit microphysical model is applied.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0320 Cloud physics and chemistry
DE: 0345 Pollution--urban and regional (0305)
DE: 0394 Instruments and techniques
DE: 4801 Aerosols (0305)
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting