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| Titel |
A data assimilative perspective of oceanic mesoscale eddy evolution during VOCALS-REx |
| VerfasserIn |
A. C. Subramanian, A. J. Miller, B. D. Cornuelle, E. Lorenzo, R. A. Weller, F. Straneo |
| 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 ; 13, no. 6 ; Nr. 13, no. 6 (2013-03-25), S.3329-3344 |
| Datensatznummer |
250018535
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| Publikation (Nr.) |
 copernicus.org/acp-13-3329-2013.pdf |
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| Zusammenfassung |
| Oceanic observations collected during the VOCALS-REx cruise time period,
1–30 November 2008, are assimilated into a regional ocean model (ROMS) using
4DVAR and then analyzed for their dynamics. Nonlinearities in the system
prevent a complete 30-day fit, so two 15-day fits for 1–15 November and
16–30 November are executed using the available observations of hydrographic
temperature and salinity, along with satellite fields of SST and sea-level
height anomaly. The fits converge and reduce the cost function significantly,
and the results indicated that ROMS is able to successfully reproduce both
large-scale and smaller-scale features of the flows observed during the
VOCALS-REx cruise. Particular attention is focused on an intensively studied
eddy at 76° W, 19° S. The ROMS fits capture this eddy as
an isolated rotating 3-D vortex with a strong subsurface signature in
velocity, temperature and anomalously low salinity. The eddy has an average
temperature anomaly of approximately −0.5 °C over a depth range
from 50–600 m and features a cold anomaly of approximately
−1 °C near 150 m depth. The eddy moves northwestward and
elongates during the second 15-day fit. It exhibits a strong signature in the
Okubo-Weiss parameter, which indicates significant nonlinearity in its
evolution. The heat balance for the period of the cruise from the ocean state
estimate reveals that the horizontal advection and the vertical mixing
processes are the dominant terms that balance the temperature tendency of the
upper layer of the ocean locally in time and space. Areal averages around the
eddies, for a 15-day period during the cruise, suggest that vertical mixing
processes generally balance the surface heating. Although, this indicates
only a small role for lateral advective processes in this region during this
period, this quasi-instantaneous heat budget analysis cannot be extended to
interpret the seasonal or long-term upper ocean heat budget in this region. |
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