Adding Oxygen to Argo: Developing a Global In Situ Observatory for Ocean Deoxygenation and Biogeochemistry.

Abstract

We propose to add dissolved oxygen sensors to the Argo (Global array of free-drifting profiling floats)float program in order to determine, on a global-scale, seasonal to decadal time-scale variations in dissolved oxygen concentrations throughout the upper ocean. Such observations are especially important to document the ocean’s expected loss of oxygen as a result of ocean warming, but there are many other benefits including the opportunity to estimate net community and export production, the assessment of changes in low oxygen regions, and improved estimates of theoceanic uptake of anthropogenic CO2. The proposed joint Argo-Oxygen program is made possible by the recent development of dissolved oxygen sensors that are both precise and stable over extended periods and can be easily integrated with the currently usedArgo floats. Results from the more than 200 oxygen equipped Argo float have not only demonstrated the feasibility of the program, but also produced already many insights and discoveries. Achieving the main goal of the Argo-Oxygenprogram does not require any appreciable changes in the deployment and operating strategies of the current Argo program and can therefore be implemented without a significant impact on Argo’s core mission. A two-phase implementation is proposed, consisting of a small set of regional pilot-studies, followed by a build-up toward a global implementation. The cost of adding oxygen sensors to all floats of the Argo program is estimated to be about USD 4.2 million per year. The proposed Argo-Oxygenprogram will add substantial value to Argo by expanding the number of Argo data users, as well as by creating new synergies between the physical and the biogeochemical ocean research communities. The new observations will also contribute to the activities of various international networks and partnerships for Earth Observing Systems.