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| Titel |
Energy and ozone fluxes over sea ice in Hudson Bay, Canada |
| VerfasserIn |
J. B. A. Muller, J. R. Dorsey, M. Flynn, M. W. Gallagher, C. J. Percival, D. E. Shallcross, A. Archibald, H. K. Roscoe, R. W. Obbard, H. M. Atkinson, J. D. Lee, S. J. Moller, L. J. Carpenter |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250058721
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| Zusammenfassung |
| Energy and ozone fluxes were measured in the surface layer over Hudson Bay sea ice during
February & March 2008 as part of the COBRA (Impact of combined iodine and bromine
release on the Arctic atmosphere) experiment which was part of the International OASIS
(Ocean-Atmosphere-Sea Ice-Snowpack) IPY programme. All components of the local
surface energy balance were measured and it was defined by net radiative cooling throughout
most of the day, mainly balanced by the conductive heat flux from the warmer sea water to
the cooler sea ice at the surface, and a small net radiative warming for a few hours
after midday. Timeseries and typical diurnal cycles of the energy fluxes will be
presented.
Unique ground-level ozone fluxes were measured by eddy covariance and deposition
velocities ranged from + 0.5 mm s-1 (deposition) to -1.5 mm s-1 (emission). Ozone profile
measurements suggested ozone flux divergence within the surface layer. The observed
bi-directional fluxes, flux divergence with height and possibly decoupled layers with no
vertical flux reveal the complexity of surface ozone fluxes in the Arctic spring time surface
layer, and show that ozone exchange with the sea ice surface is best probed using the eddy
covariance method alongside frequent or continuous profile measurements. The latter are
required to correctly interpret the measured fluxes at some height above the surface and allow
the inference of the actual exchange of ozone with the surface itself. In this study, the local
in-situ ozone-halogen photochemistry was identified as weakly controlling the measured
ozone flux, whereas horizontal advection and vertical mixing were considered important in
influencing fluxes. Under these conditions, several measurement sites would be desirable
in order to quantify the contribution of advection to the local surface exchange.
A difference in behaviour of ozone exchange over sea ice compared with snow
pack is suggested but cannot be unequivocally identified with this dataset alone. |
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