HR: 0800h
AN: A11A-0031    [Abstracts]
TI: The potential impacts of pollution on a non-drizzling stratus deck: Does aerosol number matter more than type?
AU: * Andrejczuk, M
EM: miroslaw@lanl.gov
AF: Los Alamos National Laboratory, Mail Stop D401, Los Alamos, NM 87545,
AU: Reisner, J M
EM: reisner@lanl.gov
AF: Los Alamos National Laboratory, Mail Stop D401, Los Alamos, NM 87545,
AU: Henson, H F
EM: henson@lanl.gov
AF: Los Alamos National Laboratory, Mail Stop D401, Los Alamos, NM 87545,
AU: Dubey, M K
EM: dubey@lanl.gov
AF: Los Alamos National Laboratory, Mail Stop D401, Los Alamos, NM 87545,
AU: Jeffery, C A
EM: cjeffery@lanl.gov
AF: Los Alamos National Laboratory, Mail Stop D401, Los Alamos, NM 87545,
AB: In this presentation results from a cloud-resolving model that can efficiently examine the impact of aerosols on non-drizzling stratus clouds will be shown. Because the model tracks aerosols and cloud droplets in a Lagrangian framework, it does not suffer from numerical errors associated with advection and unlike most Eulerian approaches, the method can accurately track cloud boundaries as they move across a grid cell. The model is able to reproduce cloud water mixing ratio and vertical velocity statistics from the DYCOMS-II field program. The ability of the model to assess the impact of changes in aerosol number and composition on a stratus deck will be presented. Specifically, by using activation curves appropriate for soluble, insoluble, or a mixture of both types of aerosols and for certain extreme aerosol regimes, i.e., a majority of the aerosols are hydrophobic, limiting situations will be examined in this numerical framework that may, in fact, occasionally occur in the atmosphere, e.g., an oceanic stratus field downwind of a large urban area. Expectedly, results from these simulations support previous ship track observations that for increasing aerosol numbers cloud number concentrations increase, whereas cloud droplet radii decrease near cloud top. But, these simulations also suggest that the correlation between cloud number concentration and aerosol number concentration may be a function of aerosol type.
UR: http://aerosols.lanl.gov/
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting