A case study into the measurement of ship emissions from plume intercepts of the NOAA ship Miller Freeman
Other literature type
Cappa, C. D.
Williams, E. J.
Lack, D. A.
Buffaloe, G. M.
Hayden, K. L.
Herndon, S. C.
Lerner, B. M.
Onasch, T. B.
Quinn, P. K.
(issn: 1680-7324, eissn: 1680-7324)
Emissions factors (EFs) for gas and sub-micron particle-phase species were
measured in intercepted plumes as a function of vessel speed from an
underway research vessel, the NOAA ship <i>Miller Freeman</i>, operating a medium-speed diesel
engine on low-sulfur marine gas oil (fuel sulfur content ~0.1% by weight).
The low-sulfur fuel in use conforms to the MARPOL fuel
sulfur limit within emission control areas set to take effect in 2015 and
to California-specific limits set to take effect in 2014. For many of the
particle-phase species, EFs were determined using multiple measurement
methodologies, allowing for an assessment of how well EFs from different
techniques agree. The total sub-micron PM (PM<sub>1</sub>) was dominated by
particulate black carbon (BC) and particulate organic matter (POM), with an
average POM / BC ratio of 1.3. Consideration of the POM / BC ratios observed
here with literature studies suggests that laboratory and in-stack
measurement methods may overestimate primary POM EFs relative to those
observed in emitted plumes. Comparison of four different methods for black
carbon measurement indicates that careful attention must be paid to
instrument limitations and biases when assessing EF</sub>BC</sub>. Particulate
sulfate (SO<sub>4</sub><sup>2−</sup>) EFs were extremely small and the particles
emitted by <i>Miller Freeman</i> were inefficient as cloud condensation nuclei (CCN), even at
high super saturations, consistent with the use of very low-sulfur fuel and
the overall small emitted particle sizes. All measurement methodologies
consistently demonstrate that the measured EFs (fuel mass basis) for
PM<sub>1</sub> mass, BC and POM decreased as the ship slowed. Particle number EFs
were approximately constant across the speed change, with a shift towards
smaller particles being emitted at slower speeds. Emissions factors for
gas-phase CO and formaldehyde (HCHO) both increased as the vessel slowed,
while EFs for NO<sub>x</sub> decreased and SO<sub>2</sub> EFs were approximately