Biogeochemical Floats

Autonomous profiling floats are revolutionizing the way scientists study the ocean. Before the first profiling float entered the water, our ability to measure climate, biological and chemical trends was limited in scope while large-scale studies were a costly endeavor. Today, scientists monitor the world’s oceans with thousands of floats. These developments have provided an unprecedented amount of data.

Programs like GO-BGC and Biogeochemical-Argo extend the Argo array of profiling floats to include biogeochemical sensors for pH, oxygen, nitrate, chlorophyll, suspended particles, and downwelling irradiance. They are intended to address numerous challenges in ocean science and in the management of ocean and global resources. Newly developed sensors allow profiling floats to observe biogeochemical properties with sufficient accuracy for climate studies. This data will help determine the seasonal to decadal-scale variability in biological productivity, the supply of essential nutrients from deep waters to the sunlit surface layer, ocean acidification, hypoxia, and ocean uptake of CO₂.

Like the original autonomous profiling floats, biogeochemical (BGC) autonomous profiling floats will drive a transformative shift in scientists’ ability to observe and predict the effects of climate change on ocean metabolism, carbon uptake, and living marine resource management. Monitoring of the ocean response to climatic and anthropogenic forces is critical to understanding the impacts on the global carbon cycle and its ecosystems’ responses. Increasing evidence of large-scale ocean acidification and resultant deoxygenation has emphasized the need to understand the impacts on biogeochemistry and ecosystem dynamics. 

Sea-Bird Scientific’s SBE 41 Argo and SBE 61 Deep Argo CTDs support more than 90% of the annual Argo program floats. The Navis BGC autonomous profiling floats come equipped with a CTD and biogeochemical sensors, including the SBS 83 or SBE 63 (optical dissolved oxygen) and MCOMS (backscattering and fluorescence) as well as optional Float pH and Deep SUNA (nitrate).

Many Sea-Bird Scientific sensors are used in biogeochemical monitoring on autonomous profiling floats:

• Autonomous Profiling CTD
• Oxygen
• Backscattering and Fluorescence
• pH
• Nitrate

Technical Documents

• Case Studies:
  • Paul Allen Foundation pH Sensors, Greg Ikeda, December 2018
  • Comparing ISFET and Glass Electrode pH Sensors Part 1: Stable Bath Test, Greg Ikeda, June 2018
  • Observing a Western Mediterranean overturn event with a Navis BGC autonomous profiling float, Ian Walsh, David Murphy, Geoff MacIntyre, Sea-Bird Scientific, October 2014
  • Comparison of Argo float pressure sensor performance: Druck versus Kistler, David Murphy, Sea-Bird Scientific, February 2015
• Published Article: Biogeochemical Monitoring of the Oceans Using Autonomous Profiling Floats, published in Ocean News & Technology, provides information on Sea-Bird Scientific solutions.
• Science Poster: Using Biogeochemical Models to Optimize Sampling Design for Biogeochemical Profiling Float Arrays, a CSIRO poster presentation provides information on a joint Australia-India Joint Indian Ocean Bio-Argo project.