 |
| Titel |
Measurements and modelling of molecular iodine emissions, transport and photodestruction in the coastal region around Roscoff |
| VerfasserIn |
R. J. Leigh, S. M. Ball, J. Whitehead, C. Leblanc, A. J. L. Shillings, A. S. Mahajan, H. Oetjen, J. D. Lee, C. E. Jones, J. R. Dorsey, M. Gallagher, R. L. Jones, J. M. C. Plane, P. Potin, G. McFiggans |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 23 ; Nr. 10, no. 23 (2010-12-13), S.11823-11838 |
| Datensatznummer |
250008955
|
| Publikation (Nr.) |
 copernicus.org/acp-10-11823-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
Iodine emissions from the dominant six macroalgal species in the coastal
regions around Roscoff, France, have been modelled to support the Reactive
Halogens in the Marine Boundary Layer Experiment (RHaMBLe) undertaken in
September 2006. A two-dimensional model is used to explore the relationship
between geographically resolved regional emissions (based on maps of seaweed
beds in the area and seaweed I2 emission rates previously measured in
the laboratory) and in situ point and line measurements of I2 performed
respectively by a broadband cavity ringdown spectroscopy (BBCRDS) instrument
sited on the shoreline and a long-path differential optical absorption
spectroscopy (LP-DOAS) instrument sampling over an extended light path to an
off-shore island. The modelled point and line I2 concentrations compare
quantitatively with BBCRDS and LP-DOAS measurements, and provide a link
between emission fields and the different measurement geometries used to
quantify atmospheric I2 concentrations during RHaMBLe. Total I2
emissions over the 100 km2 region around Roscoff are calculated to be
1.7×1019 molecules per second during the lowest tides.
During the night, the model replicates I2 concentrations up to 50 pptv
measured along the LP-DOAS instrument's line of sight, and predicts spikes of
several hundred pptv in certain conditions. Point I2 concentrations up
to 50 pptv are also calculated at the measurement site, in broad agreement
with the BBCRDS observations. Daytime measured concentrations of I2 at
the site correlate with modelled production and transport processes. However
substantial recycling of the photodissociated I2 is required for the
model to quantitatively match measured concentrations. This result
corroborates previous modelling of iodine and NOx chemistry in the
semi-polluted marine boundary layer which proposed a mechanism for recycling
I2 via the formation, transport and subsequent reactions of the
IONO2 reservoir compound.
The methodology presented in this paper provides a tool for linking spatially
distinct measurements to inhomogeneous and temporally varying emission
fields. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|