HR: 14:55h
AN: B43D-06    [Abstracts]
TI: Parcel Model Simulations of Aerosol-Cloud Microphysics Interactions over the Amazon
AU: * Costa, A A
EM: alexandre.costa@yale.edu
AF: Department of Geology and Geophysics, Yale University, PO BOX 208109, New Haven, CT 06520-8109 United States
AU: * Costa, A A
EM: alexandre.costa@yale.edu
AF: Funda‡ao Cearense de Meteorologia e Recursos Hˇdricos, Av. Rui Barbosa 1246, Aldeota, Fortaleza, CE 60115-221 Brazil
AU: Sherwood, S C
EM: steven.sherwood@yale.edu
AF: Department of Geology and Geophysics, Yale University, PO BOX 208109, New Haven, CT 06520-8109 United States
AB: Over tropical regions, such as the Amazon, biomass burning is a major source of aerosols that serve as cloud condensation nuclei (CCN). Changes in the cloud microphysics in association with smoke aerosols were first assessed as a possibility via modeling studies or satellite retrievals, and later verified by means of in-situ measurements. In particular, changes in the CCN field influence precipitation development in Amazon clouds, with significant suppression of warm rain processes, in agreement with previous satellite and radar studies. Nevertheless, there are still many questions regarding the formation of precipitation in the Amazon clouds that cannot be answered from the in-situ data alone: What is the role of the giant cloud condensation nuclei (GCCN) found in the different environments? How different updraft velocities influence precipitation development? How changes in the environmental humidity may influence the cloud life cycle? In this paper, we use a parcel model to simulate the development of warm rain in different aerosol regimes, from very clean to extremely polluted, as well as to explore sensitivities regarding the presence of giant CCN, the strength of the updraft velocities, and the availability of moisture at the sub-cloud layer. We found that the presence of GCCN and the control exerted by the low-level moisture over the warm rain height appear to be of comparable importance to CCN concentrationimportant to the change in rain characteristics in the transition from the dry to wet seasons over the Amazon.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0320 Cloud physics and chemistry
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting