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On the presence of giant particles downwind of ships in the marine boundary layer
Author(s) -
Sorooshian Armin,
Prabhakar Gouri,
Jonsson Haflidi,
Woods Roy K.,
Flagan Richard C.,
Seinfeld John H.
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl063179
Subject(s) - environmental science , cloud condensation nuclei , tonnage , stack (abstract data type) , atmospheric sciences , boundary layer , wake , precipitation , meteorology , sea salt , tracer , oceanography , geology , aerosol , physics , mechanics , nuclear physics , computer science , programming language
This study examines large oceangoing ships as a source of giant cloud condensation nuclei ( D p > 2 µm) due to wake and stack emissions off the California coast. Observed particle number concentrations behind 10 ships exceeded those in “control” areas, exhibiting number concentration enhancement ratios (ERs) for minimum threshold diameters of ~2, ~10, and ~20 µm as high as 2.7, 5.5, and 7.5, respectively. ER decreases with increasing downwind distance and altitude. ER becomes better correlated with ship size variables (gross tonnage, length, and beam) as the minimum size threshold increases from 2 to 20 µm, whereas ship speed has a less distinct relationship with ER. One case study of a container ship shows that there are higher concentrations of sea‐salt tracer species behind it relative to adjacent control areas. These results have implications for cloud properties and precipitation in marine boundary layers exposed to ship traffic.