Validation of SeaWiFS Chlorophyll a Concentrations in the Southern Ocean: A Revisit
Surface chlorophyll a concentrations (Ca, mg m− 3) in the Southern Ocean estimated from SeaWiFS satellite data have been reported in the literature to be significantly lower than those measured from in situ water samples using fluorometric methods. However, we found that high-resolution (∼ 1 km2/pix...
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ftunisfloridatam:oai:digitalcommons.usf.edu:msc_facpub-1851 2023-05-15T18:24:47+02:00 Validation of SeaWiFS Chlorophyll a Concentrations in the Southern Ocean: A Revisit Marrari, Marina Daly, Kendra L. Hu, Chuanmin 2006-12-01T08:00:00Z https://digitalcommons.usf.edu/msc_facpub/850 https://doi.org/10.1016/j.rse.2006.07.008 unknown Digital Commons @ University of South Florida https://digitalcommons.usf.edu/msc_facpub/850 https://doi.org/10.1016/j.rse.2006.07.008 Marine Science Faculty Publications Remote sensing Ocean color Algorithm Chlorophyll HPLC Fluorometric Southern Ocean Life Sciences article 2006 ftunisfloridatam https://doi.org/10.1016/j.rse.2006.07.008 2022-01-20T18:40:12Z Surface chlorophyll a concentrations (Ca, mg m− 3) in the Southern Ocean estimated from SeaWiFS satellite data have been reported in the literature to be significantly lower than those measured from in situ water samples using fluorometric methods. However, we found that high-resolution (∼ 1 km2/pixel) daily SeaWiFS Ca (CaSWF) data (SeaDAS4.8, OC4v4 algorithm) was an accurate measure of in situ Ca during January–February of 1998–2002 if concurrent in situ data measured by HPLC (CaHPLC) instead of fluorometric (CaFluor) measurements were used as ground truth. Our analyses indicate that CaFluor is 2.48 ± 2.23 (n = 647) times greater than CaHPLC between 0.05 and 1.5 mg m− 3 and that the percentage overestimation of in situ Ca by fluorometric measurements increases with decreasing concentrations. The ratio of CaSWF/CaHPLC is 1.12 ± 0.91 (n = 96), whereas the ratio of CaSWF/CaFluor is 0.55 ± 0.63 (n = 307). Furthermore, there is no significant bias in CaSWF (12% and − 0.07 in linear and log-transformed Ca, respectively) when CaHPLC is used as ground truth instead of CaFluor. The high CaFluor/CaHPLC ratio may be attributed to the relatively low concentrations of chlorophyll b (Cb/Ca = 0.023 ± 0.034, n = 482) and relatively high concentrations of chlorophyll c (Cc/Ca = 0.25 ± 0.59, n = 482) in the phytoplankton pigment composition when compared to values from other regions. Because more than 90% of the waters in the study area, as well as in the entire Southern Ocean (south of 60° S), have CaSWF between 0.05 and 1.5 mg m− 3, we consider that the SeaWiFS performance of Ca retrieval is satisfactory and for this Ca range there is no need to further develop a “regional” bio-optical algorithm to account for the previous SeaWiFS “underestimation”. Article in Journal/Newspaper Southern Ocean Digital Commons University of South Florida (USF) Southern Ocean Remote Sensing of Environment 105 4 367 375 |
institution |
Open Polar |
collection |
Digital Commons University of South Florida (USF) |
op_collection_id |
ftunisfloridatam |
language |
unknown |
topic |
Remote sensing Ocean color Algorithm Chlorophyll HPLC Fluorometric Southern Ocean Life Sciences |
spellingShingle |
Remote sensing Ocean color Algorithm Chlorophyll HPLC Fluorometric Southern Ocean Life Sciences Marrari, Marina Daly, Kendra L. Hu, Chuanmin Validation of SeaWiFS Chlorophyll a Concentrations in the Southern Ocean: A Revisit |
topic_facet |
Remote sensing Ocean color Algorithm Chlorophyll HPLC Fluorometric Southern Ocean Life Sciences |
description |
Surface chlorophyll a concentrations (Ca, mg m− 3) in the Southern Ocean estimated from SeaWiFS satellite data have been reported in the literature to be significantly lower than those measured from in situ water samples using fluorometric methods. However, we found that high-resolution (∼ 1 km2/pixel) daily SeaWiFS Ca (CaSWF) data (SeaDAS4.8, OC4v4 algorithm) was an accurate measure of in situ Ca during January–February of 1998–2002 if concurrent in situ data measured by HPLC (CaHPLC) instead of fluorometric (CaFluor) measurements were used as ground truth. Our analyses indicate that CaFluor is 2.48 ± 2.23 (n = 647) times greater than CaHPLC between 0.05 and 1.5 mg m− 3 and that the percentage overestimation of in situ Ca by fluorometric measurements increases with decreasing concentrations. The ratio of CaSWF/CaHPLC is 1.12 ± 0.91 (n = 96), whereas the ratio of CaSWF/CaFluor is 0.55 ± 0.63 (n = 307). Furthermore, there is no significant bias in CaSWF (12% and − 0.07 in linear and log-transformed Ca, respectively) when CaHPLC is used as ground truth instead of CaFluor. The high CaFluor/CaHPLC ratio may be attributed to the relatively low concentrations of chlorophyll b (Cb/Ca = 0.023 ± 0.034, n = 482) and relatively high concentrations of chlorophyll c (Cc/Ca = 0.25 ± 0.59, n = 482) in the phytoplankton pigment composition when compared to values from other regions. Because more than 90% of the waters in the study area, as well as in the entire Southern Ocean (south of 60° S), have CaSWF between 0.05 and 1.5 mg m− 3, we consider that the SeaWiFS performance of Ca retrieval is satisfactory and for this Ca range there is no need to further develop a “regional” bio-optical algorithm to account for the previous SeaWiFS “underestimation”. |
format |
Article in Journal/Newspaper |
author |
Marrari, Marina Daly, Kendra L. Hu, Chuanmin |
author_facet |
Marrari, Marina Daly, Kendra L. Hu, Chuanmin |
author_sort |
Marrari, Marina |
title |
Validation of SeaWiFS Chlorophyll a Concentrations in the Southern Ocean: A Revisit |
title_short |
Validation of SeaWiFS Chlorophyll a Concentrations in the Southern Ocean: A Revisit |
title_full |
Validation of SeaWiFS Chlorophyll a Concentrations in the Southern Ocean: A Revisit |
title_fullStr |
Validation of SeaWiFS Chlorophyll a Concentrations in the Southern Ocean: A Revisit |
title_full_unstemmed |
Validation of SeaWiFS Chlorophyll a Concentrations in the Southern Ocean: A Revisit |
title_sort |
validation of seawifs chlorophyll a concentrations in the southern ocean: a revisit |
publisher |
Digital Commons @ University of South Florida |
publishDate |
2006 |
url |
https://digitalcommons.usf.edu/msc_facpub/850 https://doi.org/10.1016/j.rse.2006.07.008 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Marine Science Faculty Publications |
op_relation |
https://digitalcommons.usf.edu/msc_facpub/850 https://doi.org/10.1016/j.rse.2006.07.008 |
op_doi |
https://doi.org/10.1016/j.rse.2006.07.008 |
container_title |
Remote Sensing of Environment |
container_volume |
105 |
container_issue |
4 |
container_start_page |
367 |
op_container_end_page |
375 |
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1766205676750635008 |