Plans Underway For SOSCEx III

The 3rd Southern Ocean Seasonal Cycle Experiment

The Southern Ocean is a key component of the earth system, being responsible for 50% of ocean uptake of atmospheric CO₂ and 30% of carbon export flux to the deep ocean.

Introduction

Climate models and decadal data sets predict changes in the Earth’s climate that will influence the effectiveness of the Southern Ocean CO₂ sink through adjustments to sea surface temperature, stratification and mixing (Boyd 2002), all of which affect the nutrient and light supply necessary for phytoplankton production (and associated carbon export). The challenge in predicting long term trends in the Southern Ocean carbon cycle lies in our ability to resolve interannual variability and the link between seasonal and intraseasonal dynamics in physical drivers and biogeochemical responses. Despite their importance, surface ocean processes at these scales are poorly understood and quantified due to operational limitations of ships and moorings. This has necessitated the use of autonomous, remotely sensed and modeling platforms that are able to address the temporal and spatial scale gaps in our knowledge of a hitherto under sampled ocean.

Aims

• Understanding through seasonal scale observations, the role of fine scale upper ocean physical dynamics on CO₂ fluxes and primary production in the Southern Ocean and its impact on large-scale carbon-climate sensitivities.
• To make a significant contribution to improving the way global climate models reflect CO₂ and primary productivity climate sensitivities in the Southern Ocean.

Approach

A novel aspect of SOSCEx III is the integrated multi-platform approach, which aims to explore new questions about the climate sensitivity of carbon and ecosystem dynamics and how these processes are parameterized in models.

1. Observational

The observational approach employs the research ship together with robotics-based continuous year-round, high-resolution observations of the upper ocean. The primary objective is to understand how meso- to sub-mesoscale features (eddies and fronts) interact with seasonal to subseasonal scales (heating & transient storms) to characterize the seasonal cycle of upper ocean mixed layer depth, CO₂ fluxes Fe and light availability, primary production and associated carbon export.

2. Modelling

A hierarchy of medium to ultra-high resolution forced ocean model domains (NEMO-PISCES) will be used to test our understanding of the links between surface boundary layer physical drivers and the biogeochemical response scales, especially in terms of air-sea CO₂

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