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Creators/Authors contains: "Estapa, M. L."

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  1. Abstract

    Methods commonly used to estimate net primary production (NPP) from satellite observations are now being applied to biogeochemical (BGC) profiling float observations. Insights can be gained from regional differences in float and satellite NPP estimates that reveal gaps in our understanding and guide future NPP model development. We use 7 years of BGC profiling float data from the Northeast Pacific Ocean to quantify discrepancies between float and satellite NPP estimates and decompose them into contributions associated with the platform sensing method and depth resolution of observations. We find small, systematic seasonal discrepancies in the depth‐integrated NPP (iNPP) but much larger (>±100%) discrepancies in depth‐resolved NPP. Annual iNPP estimates from the two platforms are significantly, positively correlated, suggesting that they similarly track interannual variability in the study region. Using the long‐term satellite iNPP record, we identify elevated annual iNPP during two recent marine heatwaves and gain insights about ecosystem functionality.

     
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  2. Abstract

    The complex interplay of biological and physical mechanisms comprising the ocean's biological carbon pump has not been well characterized to date, due to the difficulty of observing these mechanisms in situ at adequate spatial and temporal resolution. An annual time series is presented of direct measurements of export production and particle properties collected using optical sediment trap‐equipped profiling floats cycling every 1.5–2.5 days. The observations indicate strong variability in particle export and bio‐optical properties, influenced by the spring bloom, mesoscale eddy activity, and the mixed layer pump. Temporal and vertical decoupling of fluxes at depths ranging from 150 to 1,000 m was also observed, and remineralization length scales were more variable than predicted by temperature‐ and oxygen‐based models. Net primary production was computed from float observations using a modification of the Carbon‐based Productivity Model and used to estimate export and export (e‐) ratios, which were compared to predictions of literature export models. Mechanistic models explicitly incorporating ecosystem processes and their depth dependence may perform better at reproducing regional observations collected at high temporal resolution.

     
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