Large-scale measurements of particle size distribution and cloud condensation nuclei during the LBA/SMOCC-2002 experiment in Rondônia
Luciana
Varanda
Rizzo, Instituto de Física - USP, lrizzo@if.usp.br
(Presenting)
Theotonio
Mendes
Pauliquevis Junior, Instituto de Física - USP, theo@if.usp.br
Paulo
Artaxo, Instituto de Física - USP, artaxo@if.usp.br
Meinrat
O.
Andreae, Max Planck Institute for Chemistry, andreae@mpch-mainz.mpg.de
Göran
Frank, Max Planck Institute for Chemistry, gfrank@mpch-mainz.mpg.de
Pascal
Guyon, Max Planck Institute for Chemistry, guyon@mpch-mainz.mpg.de
The LBA/SMOCC experiment (Large-scale Biosphere-atmosphere experiment in Amazonia - SMOke, aerosols, Clouds, rainfall and Climate) was aimed at studying aerosol-cloud interactions, and the field campaign was in September - November 2002. The campaign included ground based measurements (at the Fazenda Nossa Senhora, Ouro Preto do Oeste) along with extensive aircraft measurements, totaling up 31 flights. A Bandeirante aircraft was equipped with a scanning mobility particle sizer (SMPS), a condensational particle counter (CPC), a static thermal-gradient cloud condensation nuclei (CCN) counter, and other aerosol instrumentation. Each number size distribution measured by SMPS was log-normally fitted, with the following parameters: geometric mean diameter Dpg (70 - 160 nm), geometric standard deviation sg (1.5 – 2.2), and total number concentration N (500 – 20,000 cm-3). Those parameters were influenced by the amount and kind of biomass burning emissions. The size distributions with the largest geometric mean diameters (120 – 160 nm) also showed low or moderate concentrations (N < 5,000 cm-3), typical of background conditions or areas moderately influenced by smoldering smoke. Over areas impacted by flaming smoke, the particle concentration exceeded 5,000 cm-3, and the corresponding spectra showed low geometric mean diameters (70 – 120 nm). The fine particle concentrations decreased gradually with increasing altitudes, an indication that the surface acts as a source. At profiles performed over smoke impacted areas, one could see a gradually decrease of Dpg from surface up to 1500 m altitude in average, where the influence of surface emissions is lower. Over clean areas, N and Dpg parameters remained almost constant with increasing altitudes, indicating a strong vertical mixing. At a supersaturation of 1.2%, the ratio between CCN number and total particle concentration laid between a large range (0.15 and 0.70). At a profile performed over the Fazenda Nossa Senhora, results show that droplet activation is more efficient at 2000 m high, in comparison to 470 m high. This is possibly due to the presence of cloud processed aerosols in higher altitudes.
Submetido por Luciana Varanda Rizzo em 19-MAR-2004