The following projects were funded by NOAA’s Global Ocean Monitoring and Observing Program under the 2019 National Ocean Partnership Program Broad Agency Announcement (2019 NOPP BAA) Topic 4 “Autonomous Profiling Floats for Investigating Tropical Pacific Ocean Biogeochemistry”, in partnership with NASA’s Ocean Biology and Biogeochemistry Program and CPO’s Climate Variability and Predictablity Program, and an internal NOAA competition inviting proposals to assess the efficacy of instrumented autonomous profiling floats for observing tropical Pacific Ocean biogeochemistry.

Improvements to Profiling Float Technology in Support of Equatorial Pacific Biogeochemical Studies

PI/Co-PI(s): Stephen C. Riser (University of Washington), Ken Johnson (MBARI), Brendan Carter, (JISAO/UW), Thomas Mitchell (Seabird)
Start Year: 2019 | Duration: 3 years
Partners: MBARI, Seabird

The goal of this project is to develop, build, and deploy 8-16 prototype Seabird biogeochemical (BGC) Argo profiling floats in the tropical Pacific. The project will evaluate a new design of a full suite (6-parameter) BGC Argo float with a potential pathway for commercialization. The proposed 6-parameter BGC Argo will build from the existing design of the Sea-Bird BGC Navis float, which at present includes oxygen, chlorophyll, backscatter, nitrate, and pH. To meet the requirements of the BGC Argo program for a 6-parameter float with sufficient longevity, the team will modify the current float design to: increase the buoyancy capacity and longevity of the Navis buoyancy engine; change the location of the optode O2 sensor for in-situ air calibration; add a downwelling irradiance (Ed) sensor; and experiment with a new version of the pH sensor to address pressure compensation issues.
In addition to the float development, the team will implement a new region specific, multiple linear regression (MLR) model for the tropical Pacific leveraging the new GLODAPV2 data. The regional MLR will allow for the estimation of other parameters of the inorganic carbon system (pCO2, alkalinity, DIC) from the standard suite of Argo physical and biogeochemical measurements. Estimates of pCO2 from the MLR applied to the new float data will be compared with pCO2 directly measured during Saildrone missions in the same region.

Developing an autonomous biogeochemical profiling float to monitor biological productivity, ocean-atmosphere CO2 fluxes, and hypoxia in the Tropical Pacific Ocean

PI/Co-PI(s): Sarah Purkey, Todd Martz, Lynne Talley, Dean Roemmich, Matthew Mazloff, Daniel Rudnick, Ariane Verdy (SIO-UCSD); Neil Bogue (MRV Systems LLC); Ken Johnson (MBARI)
Start Year: 2019 | Duration: 3 years
Partners: MRV Systems LLC, MBARI

The PIs will design, build and deploy new BGC Argo floats to monitor the biogeochemistry of the tropical Pacific. The PIs will modify the MRV SOLO-II float architecture and integrate to include all BGC Argo variables (i.e.temperature, salinity, oxygen, pH, nitrate, chlorophyll-a, backscatter and downwelling irradiance) and make modifications to the control and communications systems. The BGC floats will be deployed along the equator near the 5 eastern-most Tropical Pacific Observing System (TPOS) 2020 pCO2 moorings.
Finally, the PIs will also couple a BGC model to the Tropical Pacific Ocean State Estimate (TPOSE), developed under the Climate Variability and Predictability Program, to assess temporal and spatial length scales of the climate variability. Results from the length scale and formal mapping error analysis will be used to help advise TPOS 2020 on how to design the most optimized biogeochemistry observing system for the Tropical Pacific, in line with TPOS 2020’s requirements, and will provide a major BGC analysis tool.