Estimating mixed layer nitrate in the North Atlantic Ocean

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...

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Published in:Biogeosciences
Main Authors: Steinhoff, T., Friedrich, T., Hartman, S. E., Oschlies, A., Wallace, D. W. R., Körtzinger, A.
Format: Text
Language:English
Published: 2018
Subjects:
Online Access:https://doi.org/10.5194/bg-7-795-2010
https://www.biogeosciences.net/7/795/2010/
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spelling ftcopernicus:oai:publications.copernicus.org:bg1576 2023-05-15T17:27:49+02:00 Estimating mixed layer nitrate in the North Atlantic Ocean Steinhoff, T. Friedrich, T. Hartman, S. E. Oschlies, A. Wallace, D. W. R. Körtzinger, A. 2018-09-27 application/pdf https://doi.org/10.5194/bg-7-795-2010 https://www.biogeosciences.net/7/795/2010/ eng eng doi:10.5194/bg-7-795-2010 https://www.biogeosciences.net/7/795/2010/ eISSN: 1726-4189 Text 2018 ftcopernicus https://doi.org/10.5194/bg-7-795-2010 2019-12-24T09:57:30Z 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. Text North Atlantic Copernicus Publications: E-Journals Biogeosciences 7 3 795 807
institution Open Polar
collection Copernicus Publications: E-Journals
op_collection_id ftcopernicus
language English
description 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.
format Text
author Steinhoff, T.
Friedrich, T.
Hartman, S. E.
Oschlies, A.
Wallace, D. W. R.
Körtzinger, A.
spellingShingle Steinhoff, T.
Friedrich, T.
Hartman, S. E.
Oschlies, A.
Wallace, D. W. R.
Körtzinger, A.
Estimating mixed layer nitrate in the North Atlantic Ocean
author_facet Steinhoff, T.
Friedrich, T.
Hartman, S. E.
Oschlies, A.
Wallace, D. W. R.
Körtzinger, A.
author_sort Steinhoff, T.
title Estimating mixed layer nitrate in the North Atlantic Ocean
title_short Estimating mixed layer nitrate in the North Atlantic Ocean
title_full Estimating mixed layer nitrate in the North Atlantic Ocean
title_fullStr Estimating mixed layer nitrate in the North Atlantic Ocean
title_full_unstemmed Estimating mixed layer nitrate in the North Atlantic Ocean
title_sort estimating mixed layer nitrate in the north atlantic ocean
publishDate 2018
url https://doi.org/10.5194/bg-7-795-2010
https://www.biogeosciences.net/7/795/2010/
genre North Atlantic
genre_facet North Atlantic
op_source eISSN: 1726-4189
op_relation doi:10.5194/bg-7-795-2010
https://www.biogeosciences.net/7/795/2010/
op_doi https://doi.org/10.5194/bg-7-795-2010
container_title Biogeosciences
container_volume 7
container_issue 3
container_start_page 795
op_container_end_page 807
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