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Title: Sub-micrometre Particulate Matter is Primarily in Liquid Form over Amazon Rainforests

Particulate matter (PM) occurs in the Earth’s atmosphere both in liquid and non-liquid forms. The physical state affects the available physical and chemical mechanisms of growth and reactivity, ultimately affecting the number, size, and composition of the atmospheric particle population. Herein, the physical state, including the response to relative humidity (RH), was investigated on-line and in real time for PM (< 1 μm) over the tropical rain forest of central Amazonia during both the wet and dry seasons of 2013. The results show that the PM was liquid for RH > 80% across 296 to 300 K. These results, in conjunction with the distributions of RH and temperature in Amazonia, imply that near-surface submicron PM in Amazonia is liquid most of the time. The observations are consistent with laboratory experiments showing that PM produced by isoprene photo-oxidation is liquid across these meteorological conditions. The findings have implications for the mechanisms of new particle production in Amazonia, the growth of submicron particles and hence dynamics of the cloud life cycle, and the sensitivity of these processes to anthropogenic activities. An approach for inclusion of particle physical state in chemical transport models is presented.
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Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 1752-0894; KP1701000
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nature Geoscience; Journal Volume: 9; Journal Issue: 1
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
Sponsoring Org:
Country of Publication:
United States