HR: 11:50h
AN: A52A-07    [Abstracts]
TI: Effects from Multiple Species of Insoluble Aerosol Particles on the Glaciation and Precipitation Production of Deep Convective Clouds in a Tropical Atlantic Hurricane
AU: * Phillips, V T
EM: vaughanp@hawaii.edu
AF: Department of Meteorology, University of Hawaii at Manoa, HIG, 2525 Correa Road, Honolulu, HI 96822, United States
AU: Andronache, C
EM: andronac@bc.edu
AF: Boston College, Gasson Hall 012 140 Commonwealth Ave., Chestnut Hill, MA 02467, United States
AB: During July 2005, the Tropical Cloud Systems and Processes (TCSP) experiment of NASA occurred in Costa Rica. The general mission of TCSP was to investigate the formation and evolution of tropical cyclones. Improved understanding of the mechanisms and effects of ice nucleation in deep convective clouds in a given tropical cyclone has been a key goal of the TCSP program because such clouds produce much of the ice for its upper- level cirrus outflow. An empirical parametrisation of heterogeneous ice nucleation has been formulated for application in cloud and large-scale atmospheric models. It represents dependencies on predicted mass concentrations for multiple chemical species of ice nucleus (IN) aerosols. The scheme includes condensation-, immersion- and contact- freezing modes, in addition to vapour deposition, as mechanisms for heterogeneous nucleation. These species of IN include mineral dust, black carbon and biogenic particles. The scheme represents the suppression of heterogeneous nucleation at low humidities and warm subzero temperatures seen in several laboratory studies. Simulations with a microphysical model of deep convection observed in TCSP are presented. Impacts of various chemical species of IN on the mechanisms for glaciation of deep convective clouds and of their outflow to cirrus are shown. Modification of precipitation production by altered IN loadings, as seen in desert dust epsisodes near the tropical Atlantic, is discussed.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly