Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
  • BCO-DMO Processing Description
• Supplemental Files
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Project Information
• Funding

These data will be published in the pending results paper Clements et al. (2024) "Modeling the Diel Vertical Migration and Active Carbon Transport of zooplankton."

This work is based on the compilation of over 6800 profiles of particulate matter observations from Underwater Vision Profilers (UVP5) (Rainer, 2021). The biovolume of the particle size distribution is calculated as the equivalent spherical volume of the particle size distribution  (PSD), by summing the product of particle counts time particle volume in each size class. The slope of the PSD is calculated assuming a power law distribution for the particle abundance, by linear least square fit of the log of particle counts vs. the log of particle size. These quantities are estimated for the upper 2000m of the water column (Global_POC_Export_2024.nc). To convert sparse observations to a global climatology, we trained 50 ensembles of regressions trees (Random Forests, RF) to predict biovolume and slope based on their relationship to well-sampled physical and biogeochemical predictors (predictors_3D.mat).

We calculate the particle sinking speed and carbon content by combining PSD reconstruction (biovolume and slope) with an empirical relationship between particle size, carbon content and sinking speed, the parameters of which are optimized to match in situ particle flux observations (Mouw et al. 2016). The flux values are calculated as the sum of the PSD times the sinking carbon parameters, for each grid cell. The error for reconstructed quantities is given by the standard deviation of 50 independent realizations of the RF reconstructions.

Note: The "Deployments" section of this dataset is empty.  See the supplemental file "Cruise List" cruise_list.csv which contains the cruise identifier in EcoPart (EcoTaxa), year (2008-2020), and number of profiles conducted during the cruise.  More information about these cruises can be found at EcoTaxa (http://ecotaxa.obs-vlfr.fr). 

The code used to produce these datasets can be found on a public GitHub repository at https://github.com/djclements1/Global-POC-Flux (DOI: 10.5281/zenodo.12976820).

* Submitted .nc output file attached as the primary data file for this dataset. predictor .mat and .csv parameter descriptions were added as supplemental files.

.nc header information obtained using the Panoply software (since was not able to use "ncdump -h" as configured on our system due to the HDF5 format.

NSF abstract:

The oxygen deficient zones are regions in the ocean where dissolved oxygen disappears. These regions harbor unique ecosystems only found in waters without oxygen, and they are important for Earth’s climate. Specifically, the production of nitrogen gas by two microbial processes, anammox and denitrification can control how productive the oceans are. Yet how much each process shapes ocean chemistry within these areas remains unknown. This project aims to study the oxygen deficient waters of the eastern tropical North Pacific ocean to better understand the mechanisms shaping marine nitrogen and carbon chemistry. Through this work, the project will train undergraduate and graduate students at three universities. The project aims to broaden participation in and understanding of ocean sciences by developing public videos about the methods used and the science behind the project.

The investigators will conduct a research cruise in the eastern tropical North Pacific ocean, the largest oxygen deficient zone. They will measure many nutrients including inorganic carbon and nitrogen and natural abundance stable isotopes of nitrogen compounds. They will use these patterns to establish how the major reactions work together to control nitrogen cycling and gaseous nitrogen production. In addition, a high-resolution model of the ocean will reveal the influence of ocean mixing, set the timescales for reactions, and enable synthesis of the measurements into a global context. The work will determine how the input of oxygen through mixing controls chemistry, and it will distinguish between the processes restricted to the permanently anoxic core vs. those that tolerate (or are enhanced by) occasional oxygenation. Overall, the project will provide new information about nitrogen cycling pathways (anammox, denitrification, and nitrite oxidation) across the region and link the resulting isotopic signals to the global nitrogen budget.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.