Observing Biochemical Evolution Within Mode Waters Using a 3D Water Mass Atlas

Abstract

Developing an analytical tool such as the interactive 3D water mass atlas allows the exploration of a mode water’s structure, flow and biogeochemical evolution. Utilizing a combined dataset from Argo and GLODAP, the atlas visualizes the spatial and temporal distribution of ocean properties within the mode water. In this excerpt we will focus particularly on oxygen and nitrate concentrations within mode waters including the Subantarctic Mode Water (SAMW), Antarctic Intermediate Water (AAIW), and subtropical mode waters in the North Pacific, North Atlantic, South Atlantic, and Indian Oceans. Our analysis reveals consistent biogeochemical trends over the recent decades. Observations show there is an overall consistent decline in oxygen concentrations with a corresponding decline in nitrate levels. The North Pacific Subtropical Mode Water and the Indian Ocean Subtropical Mode Water exhibit opposing patterns. Opposite patterns could be attributed to regional variability in ventilation and nutrient dynamics. These trends were able to be observed through climatological anomalies and 3D visualizations. Results support the importance of the role mode waters carry in regulating oceanic oxygen and nutrient distributions. The water mass atlas website (https://mathildejutras.github.io/water-mass-atlas-1.html) and its accompanying open-source codebase within a github repository (https://github.com/tarjam777/Water-Mass-Atlas) provides a new platform for scientific evaluation of global ocean relationships. This tool works to understand the role of mode waters in ocean circulation, climate regulation and to improve ocean-climate models.