Neural network-based estimates of Southern Ocean net community production from in situ O 2 / Ar and satellite observation: a methodological study
Southern Ocean organic carbon export plays an important role in the global carbon cycle, yet its basin-scale climatology and variability are uncertain due to limited coverage of in situ observations. In this study, a neural network approach based on the self-organizing map (SOM) is adopted to constr...
Published in: | Biogeosciences |
---|---|
Main Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications
2014
|
Subjects: | |
Online Access: | https://doi.org/10.5194/bg-11-3279-2014 https://doaj.org/article/e30a8b637dbb407d856440d102c189b2 |
id |
ftdoajarticles:oai:doaj.org/article:e30a8b637dbb407d856440d102c189b2 |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:e30a8b637dbb407d856440d102c189b2 2023-05-15T13:38:50+02:00 Neural network-based estimates of Southern Ocean net community production from in situ O 2 / Ar and satellite observation: a methodological study C.-H. Chang N. C. Johnson N. Cassar 2014-06-01T00:00:00Z https://doi.org/10.5194/bg-11-3279-2014 https://doaj.org/article/e30a8b637dbb407d856440d102c189b2 EN eng Copernicus Publications http://www.biogeosciences.net/11/3279/2014/bg-11-3279-2014.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-11-3279-2014 https://doaj.org/article/e30a8b637dbb407d856440d102c189b2 Biogeosciences, Vol 11, Iss 12, Pp 3279-3297 (2014) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2014 ftdoajarticles https://doi.org/10.5194/bg-11-3279-2014 2022-12-31T13:56:01Z Southern Ocean organic carbon export plays an important role in the global carbon cycle, yet its basin-scale climatology and variability are uncertain due to limited coverage of in situ observations. In this study, a neural network approach based on the self-organizing map (SOM) is adopted to construct weekly gridded (1° × 1°) maps of organic carbon export for the Southern Ocean from 1998 to 2009. The SOM is trained with in situ measurements of O 2 / Ar-derived net community production (NCP) that are tightly linked to the carbon export in the mixed layer on timescales of one to two weeks and with six potential NCP predictors: photosynthetically available radiation (PAR), particulate organic carbon (POC), chlorophyll (Chl), sea surface temperature (SST), sea surface height (SSH), and mixed layer depth (MLD). This nonparametric approach is based entirely on the observed statistical relationships between NCP and the predictors and, therefore, is strongly constrained by observations. A thorough cross-validation yields three retained NCP predictors, Chl, PAR, and MLD. Our constructed NCP is further validated by good agreement with previously published, independent in situ derived NCP of weekly or longer temporal resolution through real-time and climatological comparisons at various sampling sites. The resulting November–March NCP climatology reveals a pronounced zonal band of high NCP roughly following the Subtropical Front in the Atlantic, Indian, and western Pacific sectors, and turns southeastward shortly after the dateline. Other regions of elevated NCP include the upwelling zones off Chile and Namibia, the Patagonian Shelf, the Antarctic coast, and areas surrounding the Islands of Kerguelen, South Georgia, and Crozet. This basin-scale NCP climatology closely resembles that of the satellite POC field and observed air–sea CO 2 flux. The long-term mean area-integrated NCP south of 50° S from our dataset, 17.9 mmol C m −2 d −1 , falls within the range of 8.3 to 24 mmol C m −2 d −1 from other model estimates. A broad ... Article in Journal/Newspaper Antarc* Antarctic Southern Ocean Directory of Open Access Journals: DOAJ Articles Antarctic Southern Ocean The Antarctic Kerguelen Pacific Indian Biogeosciences 11 12 3279 3297 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
spellingShingle |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 C.-H. Chang N. C. Johnson N. Cassar Neural network-based estimates of Southern Ocean net community production from in situ O 2 / Ar and satellite observation: a methodological study |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
Southern Ocean organic carbon export plays an important role in the global carbon cycle, yet its basin-scale climatology and variability are uncertain due to limited coverage of in situ observations. In this study, a neural network approach based on the self-organizing map (SOM) is adopted to construct weekly gridded (1° × 1°) maps of organic carbon export for the Southern Ocean from 1998 to 2009. The SOM is trained with in situ measurements of O 2 / Ar-derived net community production (NCP) that are tightly linked to the carbon export in the mixed layer on timescales of one to two weeks and with six potential NCP predictors: photosynthetically available radiation (PAR), particulate organic carbon (POC), chlorophyll (Chl), sea surface temperature (SST), sea surface height (SSH), and mixed layer depth (MLD). This nonparametric approach is based entirely on the observed statistical relationships between NCP and the predictors and, therefore, is strongly constrained by observations. A thorough cross-validation yields three retained NCP predictors, Chl, PAR, and MLD. Our constructed NCP is further validated by good agreement with previously published, independent in situ derived NCP of weekly or longer temporal resolution through real-time and climatological comparisons at various sampling sites. The resulting November–March NCP climatology reveals a pronounced zonal band of high NCP roughly following the Subtropical Front in the Atlantic, Indian, and western Pacific sectors, and turns southeastward shortly after the dateline. Other regions of elevated NCP include the upwelling zones off Chile and Namibia, the Patagonian Shelf, the Antarctic coast, and areas surrounding the Islands of Kerguelen, South Georgia, and Crozet. This basin-scale NCP climatology closely resembles that of the satellite POC field and observed air–sea CO 2 flux. The long-term mean area-integrated NCP south of 50° S from our dataset, 17.9 mmol C m −2 d −1 , falls within the range of 8.3 to 24 mmol C m −2 d −1 from other model estimates. A broad ... |
format |
Article in Journal/Newspaper |
author |
C.-H. Chang N. C. Johnson N. Cassar |
author_facet |
C.-H. Chang N. C. Johnson N. Cassar |
author_sort |
C.-H. Chang |
title |
Neural network-based estimates of Southern Ocean net community production from in situ O 2 / Ar and satellite observation: a methodological study |
title_short |
Neural network-based estimates of Southern Ocean net community production from in situ O 2 / Ar and satellite observation: a methodological study |
title_full |
Neural network-based estimates of Southern Ocean net community production from in situ O 2 / Ar and satellite observation: a methodological study |
title_fullStr |
Neural network-based estimates of Southern Ocean net community production from in situ O 2 / Ar and satellite observation: a methodological study |
title_full_unstemmed |
Neural network-based estimates of Southern Ocean net community production from in situ O 2 / Ar and satellite observation: a methodological study |
title_sort |
neural network-based estimates of southern ocean net community production from in situ o 2 / ar and satellite observation: a methodological study |
publisher |
Copernicus Publications |
publishDate |
2014 |
url |
https://doi.org/10.5194/bg-11-3279-2014 https://doaj.org/article/e30a8b637dbb407d856440d102c189b2 |
geographic |
Antarctic Southern Ocean The Antarctic Kerguelen Pacific Indian |
geographic_facet |
Antarctic Southern Ocean The Antarctic Kerguelen Pacific Indian |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_source |
Biogeosciences, Vol 11, Iss 12, Pp 3279-3297 (2014) |
op_relation |
http://www.biogeosciences.net/11/3279/2014/bg-11-3279-2014.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-11-3279-2014 https://doaj.org/article/e30a8b637dbb407d856440d102c189b2 |
op_doi |
https://doi.org/10.5194/bg-11-3279-2014 |
container_title |
Biogeosciences |
container_volume |
11 |
container_issue |
12 |
container_start_page |
3279 |
op_container_end_page |
3297 |
_version_ |
1766111583773130752 |