[A-OS21] Global ocean observation networks: Current status, results, re-assessments, and future perspectives

[AOS21-03] BGC Argo: Current Status and Challenges

*Fujiki Tetsuichi¹ (1.Japan Agency for Marine-Earth Science and Technology)

Keywords:marine ecosystems, profiling floats, biogeochemical cycle, global observation

Biogeochemical Argo (BGC Argo) Program, which was organized in 2016, aims to observe parameters related to ecosystems and biogeochemical cycles at depths of 0-2,000 m on a global scale using profiling floats. The main objectives of this program are to contribute to the following three issues: 1) clarification of biogeochemical processes (biological pumps and gas-exchange between the atmosphere and the ocean), 2) detection of changes in marine environments due to anthropogenic substances (e.g., ocean acidification and hypoxia) and assessment of their impact on marine ecosystems, and 3) improvement of carbon budget estimation and management of marine resources. Ship-based global biogeochemical observations were conducted from the 1970s to the 1990s as part of the Geochemical Ocean Sections Study (GEOSECS), the Joint Global Ocean Flux Study (JGOFS), and the World Ocean Circulation Experiment (WOCE). At present, the ship-based global biogeochemical observations continue as a part of the Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP) to obtain a wide range of biogeochemical data with high accuracy and across the ocean basin from one continent to another, covering all layers from the sea surface to just above the seafloor. However, shipboard observations are expensive, difficult to detect detailed spatial and temporal variations because of snapshot observations, and the observation period is biased toward seasons with calm sea conditions. To solve these problems, the BGC Argo Program aims to deploy 1,000 BGC Argo floats to establish a spatio-temporal high frequency biogeochemical observation network in all oceans and seasons, in collaboration with the Argo Program and GO-SHIP. Here, I will describe the current status, challenges, and future prospects of BGC Argo, which is recognized as a new observational method for biogeochemical research.