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| Titel |
Understanding the transport of Patagonian dust and its influence on marine biological activity in the South Atlantic Ocean |
| VerfasserIn |
M. S. Johnson, N. Meskhidze, V. P. Kiliyanpilakkil, S. Gassó |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 6 ; Nr. 11, no. 6 (2011-03-17), S.2487-2502 |
| Datensatznummer |
250009503
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| Publikation (Nr.) |
 copernicus.org/acp-11-2487-2011.pdf |
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| Zusammenfassung |
| The supply of bioavailable iron to the high-nitrate low-chlorophyll (HNLC)
waters of the Southern Ocean through atmospheric pathways could stimulate
phytoplankton blooms and have major implications for the global carbon
cycle. In this study, model results and remotely-sensed data are analyzed to
examine the horizontal and vertical transport pathways of Patagonian dust
and quantify the effect of iron-laden mineral dust deposition on marine
biological productivity in the surface waters of the South Atlantic Ocean
(SAO). Model simulations for the atmospheric transport and deposition of
mineral dust and bioavailable iron are carried out for two large dust
outbreaks originated at the source regions of northern Patagonia during the
austral summer of 2009. Model-simulated horizontal and vertical transport
pathways of Patagonian dust plumes are in reasonable agreement with
remotely-sensed data. Simulations indicate that the synoptic meteorological
patterns of high and low pressure systems are largely accountable for dust
transport trajectories over the SAO. According to model results and
retrievals from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite
Observations (CALIPSO), synoptic flows caused by opposing pressure systems
(a high pressure system located to the east or north-east of a low pressure
system) elevate the South American dust plumes well above the marine
boundary layer. Under such conditions, the bulk concentration of mineral
dust can quickly be transported around the low pressure system in a
clockwise manner, follow the southeasterly advection pathway, and reach the
HNLC waters of the SAO and Antarctica in ~3–4 days after emission from
the source regions of northern Patagonia. Two different mechanisms for
dust-iron mobilization into a bioavailable form are considered in this
study. A global 3-D chemical transport model (GEOS-Chem), implemented with
an iron dissolution scheme, is employed to estimate the atmospheric fluxes
of soluble iron, while a dust/biota assessment tool (Boyd et al., 2010) is applied to
evaluate the amount of bioavailable iron formed through the slow and
sustained leaching of dust in the ocean mixed layer. The effect of
iron-laden mineral dust supply on surface ocean biomass is investigated by
comparing predicted surface chlorophyll-a concentration ([Chl-a]) to
remotely-sensed data. As the dust transport episodes examined here represent
large summertime outflows of mineral dust from South American continental
sources, this study suggests that (1) atmospheric fluxes of mineral dust
from Patagonia are not likely to be the major source of bioavailable iron to
ocean regions characterized by high primary productivity; (2) even if
Patagonian dust plumes may not cause visible algae blooms, they could still
influence background [Chl-a] in the South Atlantic sector of the Southern
Ocean. |
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