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Published March 28, 2015 | Published + Supplemental Material
Journal Article Open

On the presence of giant particles downwind of ships in the marine boundary layer


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.

Additional Information

© 2015 American Geophysical Union. Received 19 JAN 2015; Accepted 1 MAR 2015; Accepted article online 4 MAR 2015; Published online 24 MAR 2015. All data used can be obtained from the corresponding author. This work was funded by ONR grants N00014-11-1-0783, N00014-10-1-0200, N00014-04-1-0118, and N00014-10-1-0811 and NSF grant AGS-1008848. Zhen Wang is acknowledged for her assistance with ship and satellite data. The Editor thanks Robert Wood and Darrel Gibson Baumgardner for their assistance in evaluating this paper.

Attached Files

Published - grl52711.pdf

Supplemental Material - grl52711-sup-0001-Supplementary.pdf


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