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Title: Harvard Bounce Apparatus GoAmazon 2014/15 Field Campaign Report

The effect of relative humidity (RH) on the physical state of particulate matter during the GoAmazon 2014/15 campaign was investigated through the use of particle rebound (or lack thereof) during impaction. The physics governing particle rebound have been previously modeled and can be attributed to the surface and material properties. The physical state of secondary organic material is regulated by several factors, including the local RH, the recent RH history in the case of hysteresis, and chemical composition. Across the range of atmospheric RH, hygroscopic water uptake can occur and transitions from higher to lower viscosity phases are possible. By varying the particulate matter water content and observing particle rebound as a function of RH, the phase state of the organic material under investigation can be determined. Custom-made impactors were employed to study the effects of RH (up to 95%) on the particle physical state. Results inferred from the particle rebound measurements indicate that, under ambient conditions (RH >80%), particulate matter in Amazonia can be considered in a liquid phase state. However, during certain time periods, a fraction (10 to 30%) of particulate matter is found to rebound during the highest RH conditions, which indicates the presence of hydrophobic particles.more » The source of the hydrophobic particulates appears to be anthropogenic, from either biomass burning or the Manaus plume.« less
 [1] ;  [1]
  1. Harvard Univ., Cambridge, MA (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Technical Report
DOE ARM Climate Research Facility, Pacific Northwest National Laboratory, Richland, WA
Research Org:
DOE Office of Science Atmospheric Radiation Measurement (ARM) Program (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Contributing Orgs:
Harvard University, Central Office of the Large Scale Biosphere Atmosphere Experiment in Amazonia, Instituto Nacional de Pesquisas da Amazonia, Universidade do Estado do Amazonia, Brazilian National Council for Scientific and Technological Development
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES Hydrophobic particulates, cloud condensation nuclei, particle phase transition, transport of pollutants, isoprenes, Manacapuru, particle rebound