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| Titel |
Estimating mixed layer nitrate in the North Atlantic Ocean |
| VerfasserIn |
T. Steinhoff, T. Friedrich, S. E. Hartman, A. Oschlies, D. W. R. Wallace, A. Körtzinger |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 7, no. 3 ; Nr. 7, no. 3 (2010-03-01), S.795-807 |
| Datensatznummer |
250004576
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| Publikation (Nr.) |
 copernicus.org/bg-7-795-2010.pdf |
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| Zusammenfassung |
| Here we present an equation for the estimation of nitrate in surface waters
of the North Atlantic Ocean (40° N to 52° N, 10° W to
60° W). The equation was derived by multiple linear regression (MLR)
from nitrate, sea surface temperature (SST) observational data and model
mixed layer depth (MLD) data. The observational data were taken from merchant
vessels that have crossed the North Atlantic on a regular basis in 2002/2003
and from 2005 to the present. It is important to find a robust and realistic
estimate of MLD because the deepening of the mixed layer is crucial for
nitrate supply to the surface. We compared model data from two models (FOAM
and Mercator) with MLD derived from float data (using various criteria). The
Mercator model gives a MLD estimate that is close to the MLD derived from
floats. MLR was established using SST, MLD from Mercator, time and latitude
as predictors. Additionally a neural network was trained with the same
dataset and the results were validated against both model data as a "ground
truth" and an independent observational dataset. This validation produced RMS
errors of the same order for MLR and the neural network approach. We conclude
that it is possible to estimate nitrate concentrations with an uncertainty of
±1.4 μmol L−1 in the North Atlantic. |
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