Simultaneous coastal measurements of ozone deposition fluxes and iodine-mediated particle emission fluxes with subsequent CCN formation Centre for Atmospheric Science, The University of Manchester, Simon Building, Oxford Road, Manchester, M13 9PL, UK
Received: 14 Sep 2009 – Published in Atmos. Chem. Phys. Discuss.: 30 Sep 2009 Abstract. Here we present the first observations of simultaneous ozone deposition
fluxes and ultrafine particle emission fluxes over an extensive
infra-littoral zone. Fluxes were measured by the eddy covariance technique at
the Station Biologique de Roscoff, on the coast of Brittany, north-west
France. This site overlooks a very wide (3 km) littoral zone controlled by
very deep tides (9.6 m) exposing extensive macroalgae beds available for
significant iodine mediated photochemical production of ultrafine particles.
The aspect at the Station Biologique de Roscoff provides an extensive and
relatively flat, uniform fetch within which micrometeorological techniques
may be utilized to study links between ozone deposition to macroalgae (and
sea water) and ultrafine particle production.
Revised: 14 Dec 2009 – Accepted: 22 Dec 2009 – Published: 13 Jan 2010
Ozone deposition to seawater at high tide was significantly slower
(vd[O3]=0.302±0.095 mm s−1) than low tidal
deposition. A statistically significant difference in the deposition
velocities to macroalgae at low tide was observed between night time
(vd[O3]=1.00±0.10 mm s−1) and daytime
(vd[O3]=2.05±0.16 mm s−1) when ultrafine particle
formation results in apparent particle emission. Very high emission fluxes of
ultrafine particles were observed during daytime periods at low tides ranging
from 50 000 particles cm−2 s−1 to greater than
200 000 particles cm−2 s−1 during some of the lowest tides.
These emission fluxes exhibited a significant relationship with particle
number concentrations comparable with previous observations at another
location. Apparent particle growth rates were estimated to be in the range
17–150 nm h−1 for particles in the size range 3–10 nm. Under
certain conditions, particle growth may be inferred to continue to
greater than 120 nm over tens of hours; sizes at which they may readily
behave as cloud condensation nuclei (CCN) under reasonable supersaturations
that may be expected to pertain at the top of the marine boundary layer.
These results link direct depositional loss and photochemical destruction of
ozone to the formation of particles and hence CCN from macroalgal emissions
at a coastal location.
Citation: Whitehead, J. D., McFiggans, G., Gallagher, M. W., and Flynn, M. J.: Simultaneous coastal measurements of ozone deposition fluxes and iodine-mediated particle emission fluxes with subsequent CCN formation, Atmos. Chem. Phys., 10, 255-266, doi:10.5194/acp-10-255-2010, 2010.