Southern Ocean Time Series (SOTS) Quality Assessment and Control Report. Salinity Records 2009-2020. Version 2.0

Abstract

The Southern Ocean Time Series (SOTS) Observatory located near 141°E and 47°S provides high temporal resolution observations in Subantarctic waters. It is focused on the Subantarctic Zone because waters formed at the surface in this region by deep wintertime convection slide under warmer subtropical and tropical waters, carrying CO2 and heat into the deep ocean, where it is out of contact with the atmosphere. This process also supplies oxygen for deep ocean ecosystems, and exports nutrients that fuel ~70% of global ocean primary production. Local biological production also impacts carbon cycling and the SOTS moorings measure several variables important to these processes. This report describes the quality control (QC) procedures applied to salinity data collected from the SOTS moorings between 2006 and 2020. These measurements help to quantify heat and freshwater transfers, help to distinguish Eulerian from Lagrangian influences on seasonal records, and contribute to understanding controls on surface mixed layer depth (and thus light availability to primary production). The quality-controlled datasets are publicly available via the Australian Ocean Data Network (AODN) Portal: Open Access to Ocean Data (aodn.org.au). This report should be consulted when using the data. The QC procedures apply automated tests following QARTOD recommendations for in-situ temperature and salinity data quality control (Bushnell and Worthington, 2020), with the test parameters tailored to reflect regional oceanography. QARTOD is an initiative of the US Integrated Ocean Observing System for Quality Assurance of Real Time Oceanographic Data: https://ioos.noaa.gov/project/qartod/. The procedures detailed in this document yield QC flags for each observation, as well as uncertainty estimates for the overall results. They also now (Version 2.0 onward) provide some adjustments, but do not produce a gridded data set (that task will be addressed in a subsequent report).