The age of iron and iron source attribution in the ocean
The article of record as published may be found at http://dx.doi.org/10.1002/2016GB005418 All iron data used in this study are available from GEOTRACES (http://www.bodc.ac.uk/geotraces/data) We use tracers to partition dissolved iron (dFe) into the contributions from each source within a numerical m...
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ftnavalpschool:oai:calhoun.nps.edu:10945/57209 2024-06-09T07:40:12+00:00 The age of iron and iron source attribution in the ocean Holzer, Mark Frants, Marina Pasquier, Benoît Naval Postgraduate School (U.S.) Engineering and Applied Sciences 2016-10-12 21 p. application/pdf https://hdl.handle.net/10945/57209 unknown AGU Publications https://hdl.handle.net/10945/57209 This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States. Iron concentrations are partitioned according to source and time since injection into the ocean for a family of inverse-model estimates Iron concentration anomalies due to source removal underestimate the true source contribution because scavenging is nonlinear Most iron in the Southern Ocean euphotic zone is upwelled regenerated iron deposited from the atmosphere several hundred years earlier Research Article 2016 ftnavalpschool 2024-05-15T01:02:41Z The article of record as published may be found at http://dx.doi.org/10.1002/2016GB005418 All iron data used in this study are available from GEOTRACES (http://www.bodc.ac.uk/geotraces/data) We use tracers to partition dissolved iron (dFe) into the contributions from each source within a numerical model of the iron cycle without perturbing the system. These contributions are further partitioned according to the time since injection into the ocean, which defines their iron-age spectrum and mean iron age. The utility of these diagnostics is illustrated for a family of inverse model estimates of the iron cycle, constrained by a data-assimilated circulation and available dFe measurements. The source contributions are compared with source anomalies defined as the differences between solutions with and without the source in question. We find that in the Southern Ocean euphotic zone, the hydrothermal and sediment contributions range from 15% to 30% of the total each, which the anomalies underestimate by a factorof∼2becauseofthenonlinearityofscavenging.Theironageisonlyresetbyscavengingandattains a mean of several hundred years in the Southern Ocean euphotic zone, revealing that aeolian iron there is supplied primarily from depth as regenerated dFe. Tagging iron according to source region and pathways shows that 70–80% of the aeolian dFe in the euphotic zone near Antarctica is supplied from north of 46∘S via paths that reach below 1 km depth. Hydrothermal iron has the oldest surface mean ages on the order of middepth ventilation times. A measure of uncertainty is provided by the systematic variations of our diagnostics across the family of iron cycle estimates, each member of which has a different aeolian sourcestrength. Australian Research Council grant DP120100674 Australian Research Council Government of Monaco Scientific Centre of Monaco Frères Louis et Max Principale Foundation Cuomo Foundation Article in Journal/Newspaper Antarc* Antarctica Southern Ocean Naval Postgraduate School: Calhoun Southern Ocean |
institution |
Open Polar |
collection |
Naval Postgraduate School: Calhoun |
op_collection_id |
ftnavalpschool |
language |
unknown |
topic |
Iron concentrations are partitioned according to source and time since injection into the ocean for a family of inverse-model estimates Iron concentration anomalies due to source removal underestimate the true source contribution because scavenging is nonlinear Most iron in the Southern Ocean euphotic zone is upwelled regenerated iron deposited from the atmosphere several hundred years earlier |
spellingShingle |
Iron concentrations are partitioned according to source and time since injection into the ocean for a family of inverse-model estimates Iron concentration anomalies due to source removal underestimate the true source contribution because scavenging is nonlinear Most iron in the Southern Ocean euphotic zone is upwelled regenerated iron deposited from the atmosphere several hundred years earlier Holzer, Mark Frants, Marina Pasquier, Benoît The age of iron and iron source attribution in the ocean |
topic_facet |
Iron concentrations are partitioned according to source and time since injection into the ocean for a family of inverse-model estimates Iron concentration anomalies due to source removal underestimate the true source contribution because scavenging is nonlinear Most iron in the Southern Ocean euphotic zone is upwelled regenerated iron deposited from the atmosphere several hundred years earlier |
description |
The article of record as published may be found at http://dx.doi.org/10.1002/2016GB005418 All iron data used in this study are available from GEOTRACES (http://www.bodc.ac.uk/geotraces/data) We use tracers to partition dissolved iron (dFe) into the contributions from each source within a numerical model of the iron cycle without perturbing the system. These contributions are further partitioned according to the time since injection into the ocean, which defines their iron-age spectrum and mean iron age. The utility of these diagnostics is illustrated for a family of inverse model estimates of the iron cycle, constrained by a data-assimilated circulation and available dFe measurements. The source contributions are compared with source anomalies defined as the differences between solutions with and without the source in question. We find that in the Southern Ocean euphotic zone, the hydrothermal and sediment contributions range from 15% to 30% of the total each, which the anomalies underestimate by a factorof∼2becauseofthenonlinearityofscavenging.Theironageisonlyresetbyscavengingandattains a mean of several hundred years in the Southern Ocean euphotic zone, revealing that aeolian iron there is supplied primarily from depth as regenerated dFe. Tagging iron according to source region and pathways shows that 70–80% of the aeolian dFe in the euphotic zone near Antarctica is supplied from north of 46∘S via paths that reach below 1 km depth. Hydrothermal iron has the oldest surface mean ages on the order of middepth ventilation times. A measure of uncertainty is provided by the systematic variations of our diagnostics across the family of iron cycle estimates, each member of which has a different aeolian sourcestrength. Australian Research Council grant DP120100674 Australian Research Council Government of Monaco Scientific Centre of Monaco Frères Louis et Max Principale Foundation Cuomo Foundation |
author2 |
Naval Postgraduate School (U.S.) Engineering and Applied Sciences |
format |
Article in Journal/Newspaper |
author |
Holzer, Mark Frants, Marina Pasquier, Benoît |
author_facet |
Holzer, Mark Frants, Marina Pasquier, Benoît |
author_sort |
Holzer, Mark |
title |
The age of iron and iron source attribution in the ocean |
title_short |
The age of iron and iron source attribution in the ocean |
title_full |
The age of iron and iron source attribution in the ocean |
title_fullStr |
The age of iron and iron source attribution in the ocean |
title_full_unstemmed |
The age of iron and iron source attribution in the ocean |
title_sort |
age of iron and iron source attribution in the ocean |
publisher |
AGU Publications |
publishDate |
2016 |
url |
https://hdl.handle.net/10945/57209 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Antarc* Antarctica Southern Ocean |
genre_facet |
Antarc* Antarctica Southern Ocean |
op_relation |
https://hdl.handle.net/10945/57209 |
op_rights |
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States. |
_version_ |
1801383657719463936 |