Microphysics of Amazonian aerosol under pristine condition and the impact from the Manaus urban plume observed during the GoAmazon campaign

 

Authors

John Hubbe — Pacific Northwest National Laboratory
Jennifer M. Comstock — Pacific Northwest National Laboratory
Mikhail S. Pekour — Pacific Northwest National Laboratory
Jian Wang — Washington University in St. Louis
Gunnar I. Senum — Brookhaven National Laboratory
Stephen R. Springston — Brookhaven National Laboratory
Anne Jefferson — NOAA- Earth System Research Laboratory
Scot T. Martin — Harvard University
Jason Tomlinson — Pacific Northwest National Laboratory
Lizabeth M Alexander — Pacific Northwest National Laboratory
Arthur J Sedlacek — Brookhaven National Laboratory
James Smith — University of California, Irvine
Jose-Luis Jimenez — University of Colorado
Chongai Kuang — Brookhaven National Laboratory
John E Shilling — Pacific Northwest National Laboratory
Fan Mei — Pacific Northwest National Laboratory
Douglas A. Day — University of Colorado, Boulder
Rodrigo Augusto Souza — Universidade do Estado do Amazonas
Luiz Augusto Toledo Machado — INPE-CPTEC
Karla Longo — National Institute for Space Research (INPE)
Brett Palm — University of Colorado
Henrique de Melo Jorge Barbosa — University of Maryland, Baltimore County
Suzane Simoes De Sa — Harvard University
Ryan Thalman — Brookhaven National Laboratory
Pedro Campuzano-Jost — University of Colorado-Boulder
Antonio Ocimar Manzi — Instituto Nacional de Pesquisas da Amazonia
Meinrat Andreae — Max Planck Institute of Chemistry
Christopher Pohlker — Max Planck Institute for Chemistry
Paulo Artaxo — University of Sao Paulo
Gerson Paiva Almeida — State University of Ceara
Joel Brito —

Category

General Topics – Aerosol

Description

The Green Ocean Amazon (GoAmazon) campaign takes place from January 2014 to December 2015 in the vicinity of Manaus, Brazil. One of the main objectives of GoAmazon is to study the aerosol lifecycle under pristine condition and the impact from Manaus urban plume. During GoAmazon, comprehensive characterization of aerosol and trace gases are carried out both at surface sites continuously, and onboard the DOE Gulfstream-1 (G-1) research aircraft from February 15th to March 25th (wet season), and from September 5th to October 15th, 2014 (dry season). Here we present diurnal variation of aerosol properties, including aerosol size distribution and CCN spectrum observed at the T0a site (Amazon Tall Tower Observatory northeast of Manaus) and the T3 site (60 km to the west of Manaus). Also shown are vertical distributions of aerosol observed onboard the G-1. During the wet season, Aerosol under pristine conditions often exhibited a bimodal size distribution with an average concentration of ~320 cm^-3. The vertical profile of aerosol size distribution suggests the entrainment of free troposphere aerosol may contribute substantially to the particle number concentration in the boundary layer. The sources and sinks of aerosol particles under the pristine conditions during the wet season are discussed. During the dry season, background aerosol concentration increased by a factor of ~5 to ~ 1500 cm^-3, due to a combination of regional biomass burning emissions and other factors. Background aerosol size distribution was typically unimodal with the mode diameter between 100 and 200 nm. Measurements show strongly enhanced nucleation and Aiken mode particle concentrations in the Manaus plume. As the plume traveled downwind, particle growth and higher CCN activation fraction were observed. The particle growth inside the plume is likely due to condensation of secondary species and coagulation. The impact of the Manaus urban plume on aerosol size distribution, CCN spectrum, and optical properties are examined, and the results from wet and dry seasons are compared.