The sensitivity of Southern Ocean biogeochemical cycles to vertical mixing ...

• Main Author: Ellison, Elizabeth
• Format: Doctoral or Postdoctoral Thesis
• Language: unknown
• Published: Imperial College London 2023
• Subjects: Southern Ocean
• Online Access: https://dx.doi.org/10.25560/108737; http://spiral.imperial.ac.uk/handle/10044/1/108737

The Southern Ocean (SO) plays a critical role in global overturning circulation and biogeochemical cycles, connecting the world’s major ocean basins and facilitating the upwelling of deep waters. Understanding the physical processes occurring in the SO is crucial to understand and model our climate system. While surface-intensified turbulent mixing significantly affects biogeochemical cycles, the importance of variations in the weaker background mixing below the mixed layer is generally overlooked. Background subsurface mixing rates in the SO vary greatly in space and time. The processes known to induce ocean background turbulence are typically not represented in models, and there is great uncertainty in the parameterisation of this mixing. This thesis investigates the sensitivity of biogeochemical tracers to altered SO diapycnal mixing. Firstly, we show that changes to SO mixing over a modest range alter Atlantic biogeochemical tracer distributions over short and long timescales. On annual to decadal ...