Revisiting Ocean Color algorithms for chlorophyll a and particulate organic carbon in the Southern Ocean using biogeochemical floats
The Southern Ocean (SO, oceans south of 30 oS) ecosystem plays a key role in global carbon cycles by sinking a major part (43 %) of the anthropogenic CO2, and being an important source of nutrients for primary producers. However, undersampling of SO biogeochemical properties limits our understanding...
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| Format: | Text |
| Language: | unknown |
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DigitalCommons@UMaine
2017
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| Online Access: | https://digitalcommons.library.umaine.edu/etd/2654 https://digitalcommons.library.umaine.edu/context/etd/article/3703/viewcontent/M_HaentjensNils_Final.pdf |
| Summary: | The Southern Ocean (SO, oceans south of 30 oS) ecosystem plays a key role in global carbon cycles by sinking a major part (43 %) of the anthropogenic CO2, and being an important source of nutrients for primary producers. However, undersampling of SO biogeochemical properties limits our understanding of the mechanisms taking place in this remote area. The Southern Ocean Carbon and Climate Observing and Modeling project (SOCCOM) has been deploying a large number of autonomous biogeochemical floats to study the SO (as of December 2016, 74 floats out of 200 have been deployed). SOCCOM floats measurements can be used to extend remote sensing chlorophyll a (chla) and POC products under the clouds or during the polar night as well as adding the depth dimension to the satellites view of the SO. Chlorophyll a concentrations measured by fluorometers (exciting/detecting light at 470/685 nm) embedded on the floats and particulate organic carbon (POC) concentrations derived from backscattering coefficients (at 700 nm) were calibrated with samples collected during the floats’ deployment cruise. Float chla and POC were compared with products derived from observations of the Moderate Resolution Imaging Spectroradiometer Aqua (MODIS) and the Visible Infrared Imaging Radioneter Suite (VIIRS) sensors. We find the Ocean Color Index (OCI) global algorithm to agree well with the matchups (within 9 %, on average, for VIIRS and 12 %, on average, for MODIS). SO specific algorithms estimating chla are offset by ~45 % south of the Sea Ice Extent Front (~ 60 oS). The remote sensing POC algorithm currently used by NASA agrees well with the float estimates throughout the SO. |
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