On the presence of giant particles downwind of ships in the marine boundary layer
Author
Sorooshian, Armin
Prabhakar, Gouri
Jonsson, Haflidi
Woods, Roy K.
Flagan, Richard C.
Seinfeld, John H.
Date
2015Metadata
Show full item recordAbstract
This study examines large oceangoing ships as a source of giant cloud condensation nuclei
(Dp>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 theminimumsize threshold increases from2 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.
Description
The article of record as published may be located at http://dx.doi.org/10.1002/2015GL063179