Moutier, WilliamThomalla, Sandy JBernard, StewartWind, GRyan-Keogh, Thomas JSmith, Marié E2020-03-192020-03-192019-07Moutier, W. (et.al.). 2019. Evaluation of chlorophyll-a and POC MODIS aqua products in the Southern Ocean. Remote Sensing, v11(15), pp1-18.2072-4292https://www.mdpi.com/2072-4292/11/15/1793https://doi.org/10.3390/rs11151793http://hdl.handle.net/10204/11335Copyright: 2019. MDPI AG. This is the fulltext version of the work.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 Sat ) and Particulate Organic Carbon (POC sat ) 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 insitu ) from both High Performance Liquid Chromatography (C HPLC ) and fluorometry (C Fluo ). 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 Sat :C insitu ratios were 0.89 (N = 46) and 0.49 (N = 73) for C HPLC and C Fluo respectively. Differences between C HPLC and C Fluo 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 insitu 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.enAlgorithmChlorophyllFluorometryHPLCParticulate organic carbonRemote sensingSouthern OceanArticleMoutier, W., Thomalla, S. J., Bernard, S., Wind, G., Ryan-Keogh, T. J., & Smith, M. E. (2019). Evaluation of chlorophyll-a and POC MODIS aqua products in the Southern Ocean. http://hdl.handle.net/10204/11335Moutier, William, Sandy J Thomalla, Stewart Bernard, G Wind, Thomas J Ryan-Keogh, and Marie E Smith "Evaluation of chlorophyll-a and POC MODIS aqua products in the Southern Ocean." (2019) http://hdl.handle.net/10204/11335Moutier W, Thomalla SJ, Bernard S, Wind G, Ryan-Keogh TJ, Smith ME. Evaluation of chlorophyll-a and POC MODIS aqua products in the Southern Ocean. 2019; http://hdl.handle.net/10204/11335.TY - Article AU - Moutier, William AU - Thomalla, Sandy J AU - Bernard, Stewart AU - Wind, G AU - Ryan-Keogh, Thomas J AU - Smith, Marie E AB - 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 Sat ) and Particulate Organic Carbon (POC sat ) 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 insitu ) from both High Performance Liquid Chromatography (C HPLC ) and fluorometry (C Fluo ). 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 Sat :C insitu ratios were 0.89 (N = 46) and 0.49 (N = 73) for C HPLC and C Fluo respectively. Differences between C HPLC and C Fluo 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 insitu 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. DA - 2019-07 DB - ResearchSpace DP - CSIR KW - Algorithm KW - Chlorophyll KW - Fluorometry KW - HPLC KW - Particulate organic carbon KW - Remote sensing KW - Southern Ocean LK - https://researchspace.csir.co.za PY - 2019 SM - 2072-4292 T1 - Evaluation of chlorophyll-a and POC MODIS aqua products in the Southern Ocean TI - Evaluation of chlorophyll-a and POC MODIS aqua products in the Southern Ocean UR - http://hdl.handle.net/10204/11335 ER -