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| Titel |
Numerical simulation of the atmospheric circulation over Tahiti |
| VerfasserIn |
P. Heinrich, L. Vignon, Y. Grillon |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250020627
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| Zusammenfassung |
| Atmospheric transport of 2 natural radionuclides (7Be and 210Pb) is simulated over the globe
by a General Circulation Model (GCM). Results are analyzed at Tahiti station to define its
capacity to detect a pollutant circulating through Pacific Ocean. Numerical results over the
years 2004 and 2006 show that the recorded time series of 7Be and 210Pb air concentrations
are poorly reproduced by this global model, where Tahiti is not described due to the
insufficient resolution (1.875Ë x1.25Ë horizontally and 19 levels vertically). In order to
account for the observed discrepancies, circulation over Tahiti is analyzed in details for
selected periods. Simulated wind fields are calculated by the mesoscale meteorological
model WRF using 4 nested grids with resolutions ranging from 27 km to 1 km. The
calculated wind fields are validated by those available at the Tahiti station and at airport.
Results of WRF show that this tall island acts a mechanical obstacle on the flow and
that the station is strongly affected by local sea-breezes. Despite these site-specific
effects, simulations of atmospheric transport for different regimes demonstrate the
coupling of the station at a daily scale with the general circulation. Sensitivity tests on
210Pb transport demonstrate the dominant role of deep convection in the GCM. |
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