This atlas uses all of the available full water column profiles of oxygen, salinity and temperature available as part of the World Ocean Atlas released in 2018. Instead of optimal interpolation we use the Data Interpolating Variational Analysis (DIVA) approach to map the available profiles onto 108 depth levels between the surface and 6800 m, covering more than 99% of ocean volume. This 1/2° x 1/2° degree atlas covers the period 1955 to 2018 in 1 year intervals. The DIVA method has significant benefits over traditional optimal interpolation. It allows the explicit inclusion of advection and boundary constraints thus offering improvements in the representations of oxygen, salinity and temperature in regions of strong flow and near coastal boundaries. We demonstrate these benefits of this mapping approach with some examples from this atlas. We can explore the regional and temporal variations of oxygen in the global oceans. Preliminary analyses confirm earlier analyses that the oxygen minimum zone in the eastern Pacific Ocean has expanded and intensified. Oxygen inventory changes between 1970 and 2010 are assessed and compared against prior studies. We find that the full ocean oxygen inventory decreased by 0.84% ± 0.42%. For this period temperature driven solubility changes explain about 21% of the oxygen decline over the full water column, in the upper 100 m solubility changes can explain all of the oxygen decrease, for the 100-600 m depth range it can explain only 29%, 19% between 600 m and 1000 m, and just 11% in the deep ocean.

The main purpose of the study was to gain a greater understanding of the chemical and biological characteristics of sites in the D'Entrecasteaux Channel and offshore of the Derwent Estuary between North West Bay and Betsey Island. Four transects were completed on the 5th and 6th of April 2022 to achieve this. A SBE 55 ECO Water Sampler Conductivity, Temperature and Depth (CTD) Rosette was used to collect depth, temperature, conductivity, salinity, density, dissolved oxygen, pH, turbidity, fluorescence and pressure data. Water samples collected at three depths using Niskin bottles were used to obtain discrete measurements of oxygen, pH, alkalinity and phosphorous at sea, and discrete measurements of chlorophyll-a, ammonia, NOx, nitrite, nitrate, phosphate and silicate in a laboratory setting. A plankton tow net was used to roughly measure the abundance of plankton at each site and a Secchi disk was used to discern the Secchi depth.

The aim of this trip was to investigate the salt wedge of the Derwent estuary, looking at the different properties along and across the estuary. This was achieved by examining; temperature, salinity, chlorophyll-a concentration, nutrients (including nitrate, ammonia, phosphate and silicate), pressure, turbidity, fluorescence, dissolved oxygen and pH. Sampling took place in the morning, in sunny, relatively calm conditions with the low tide on the sampling day at approximately 11:04 am. Two transects were used, with three different locations tested along the estuary and four tested across, at the approximate locations: (-42.94014, 147.38385), (-42.96321, 147.57525), (-42.98388, 147.37083), (-42.9795, 147.336), (-42.9744, 147.3585), (-42.97594, 147.36394) and (-42.97616, 147.38914). Sampling consisted of CTD sensor measurements, a plankton net tow, Secchi disk measurements, and a collection of water samples for analysis.