Evaluation of Chlorophyll-a and POC MODIS Aqua Products in the Southern Ocean
The Southern Ocean (SO) is highly sensitive to climate change. Therefore, an accurate estimate of phytoplankton biomass is key to being able to predict the climate trajectory of the 21st century. In this study, MODerate resolution Imaging Spectroradiometer (MODIS), on board EOS Aqua spacecraft, Leve...
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ftmdpi:oai:mdpi.com:/2072-4292/11/15/1793/ 2023-08-20T04:09:56+02:00 Evaluation of Chlorophyll-a and POC MODIS Aqua Products in the Southern Ocean William Moutier Sandy Thomalla Stewart Bernard Galina Wind Thomas Ryan-Keogh Marié Smith agris 2019-07-31 application/pdf https://doi.org/10.3390/rs11151793 EN eng Multidisciplinary Digital Publishing Institute Ocean Remote Sensing https://dx.doi.org/10.3390/rs11151793 https://creativecommons.org/licenses/by/4.0/ Remote Sensing; Volume 11; Issue 15; Pages: 1793 remote sensing ocean color algorithm chlorophyll HPLC fluorometry particulate organic carbon southern ocean Text 2019 ftmdpi https://doi.org/10.3390/rs11151793 2023-07-31T22:28:52Z The Southern Ocean (SO) is highly sensitive to climate change. Therefore, an accurate estimate of phytoplankton biomass is key to being able to predict the climate trajectory of the 21st century. In this study, MODerate resolution Imaging Spectroradiometer (MODIS), on board EOS Aqua spacecraft, Level 2 (nominal 1 km × 1 km resolution) chlorophyll-a (C S a t ) and Particulate Organic Carbon (POC s a t ) products are evaluated by comparison with an in situ dataset from 11 research cruises (2008–2017) to the SO, across multiple seasons, which includes measurements of POC and chlorophyll-a (C i n s i t u ) from both High Performance Liquid Chromatography (C H P L C ) and fluorometry (C F l u o ). Contrary to a number of previous studies, results highlighted good performance of the algorithm in the SO when comparing estimations with HPLC measurements. Using a time window of ±12 h and a mean satellite chlorophyll from a 5 × 5 pixel box centered on the in situ location, the median C S a t :C i n s i t u ratios were 0.89 (N = 46) and 0.49 (N = 73) for C H P L C and C F l u o respectively. Differences between C H P L C and C F l u o were associated with the presence of diatoms containing chlorophyll-c pigments, which induced an overestimation of chlorophyll-a when measured fluorometrically due to a potential overlap of the chlorophyll-a and chlorophyll-c emission spectra. An underestimation of ∼0.13 mg m − 3 was observed for the global POC algorithm. This error was likely due to an overestimate of in situ POC i n s i t u measurements from the impact of dissolved organic carbon not accounted for in the blank correction. These results highlight the important implications of different in situ methodologies when validating ocean colour products. Text Southern Ocean MDPI Open Access Publishing Southern Ocean Remote Sensing 11 15 1793 |
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Open Polar |
collection |
MDPI Open Access Publishing |
op_collection_id |
ftmdpi |
language |
English |
topic |
remote sensing ocean color algorithm chlorophyll HPLC fluorometry particulate organic carbon southern ocean |
spellingShingle |
remote sensing ocean color algorithm chlorophyll HPLC fluorometry particulate organic carbon southern ocean William Moutier Sandy Thomalla Stewart Bernard Galina Wind Thomas Ryan-Keogh Marié Smith Evaluation of Chlorophyll-a and POC MODIS Aqua Products in the Southern Ocean |
topic_facet |
remote sensing ocean color algorithm chlorophyll HPLC fluorometry particulate organic carbon southern ocean |
description |
The Southern Ocean (SO) is highly sensitive to climate change. Therefore, an accurate estimate of phytoplankton biomass is key to being able to predict the climate trajectory of the 21st century. In this study, MODerate resolution Imaging Spectroradiometer (MODIS), on board EOS Aqua spacecraft, Level 2 (nominal 1 km × 1 km resolution) chlorophyll-a (C S a t ) and Particulate Organic Carbon (POC s a t ) products are evaluated by comparison with an in situ dataset from 11 research cruises (2008–2017) to the SO, across multiple seasons, which includes measurements of POC and chlorophyll-a (C i n s i t u ) from both High Performance Liquid Chromatography (C H P L C ) and fluorometry (C F l u o ). Contrary to a number of previous studies, results highlighted good performance of the algorithm in the SO when comparing estimations with HPLC measurements. Using a time window of ±12 h and a mean satellite chlorophyll from a 5 × 5 pixel box centered on the in situ location, the median C S a t :C i n s i t u ratios were 0.89 (N = 46) and 0.49 (N = 73) for C H P L C and C F l u o respectively. Differences between C H P L C and C F l u o were associated with the presence of diatoms containing chlorophyll-c pigments, which induced an overestimation of chlorophyll-a when measured fluorometrically due to a potential overlap of the chlorophyll-a and chlorophyll-c emission spectra. An underestimation of ∼0.13 mg m − 3 was observed for the global POC algorithm. This error was likely due to an overestimate of in situ POC i n s i t u measurements from the impact of dissolved organic carbon not accounted for in the blank correction. These results highlight the important implications of different in situ methodologies when validating ocean colour products. |
format |
Text |
author |
William Moutier Sandy Thomalla Stewart Bernard Galina Wind Thomas Ryan-Keogh Marié Smith |
author_facet |
William Moutier Sandy Thomalla Stewart Bernard Galina Wind Thomas Ryan-Keogh Marié Smith |
author_sort |
William Moutier |
title |
Evaluation of Chlorophyll-a and POC MODIS Aqua Products in the Southern Ocean |
title_short |
Evaluation of Chlorophyll-a and POC MODIS Aqua Products in the Southern Ocean |
title_full |
Evaluation of Chlorophyll-a and POC MODIS Aqua Products in the Southern Ocean |
title_fullStr |
Evaluation of Chlorophyll-a and POC MODIS Aqua Products in the Southern Ocean |
title_full_unstemmed |
Evaluation of Chlorophyll-a and POC MODIS Aqua Products in the Southern Ocean |
title_sort |
evaluation of chlorophyll-a and poc modis aqua products in the southern ocean |
publisher |
Multidisciplinary Digital Publishing Institute |
publishDate |
2019 |
url |
https://doi.org/10.3390/rs11151793 |
op_coverage |
agris |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Remote Sensing; Volume 11; Issue 15; Pages: 1793 |
op_relation |
Ocean Remote Sensing https://dx.doi.org/10.3390/rs11151793 |
op_rights |
https://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.3390/rs11151793 |
container_title |
Remote Sensing |
container_volume |
11 |
container_issue |
15 |
container_start_page |
1793 |
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