Spatial and Temporal Statistics for Validating Aquarius Sea Surface Salinity Measurements with Argo in Situ Observations

Abstract:

Salinity is an indicator of the interaction between ocean circulation and the global water cycle, which in turn affects the regulation of the Earth's climate. Due to its fine spatial and temporal coverage, Aquarius presents an ideal measurement system for fully characterizing the distribution and properties of sea surface salinity. This leads to the need for the proper validation of the Aquarius salinity product with independent salinity measurements. Using the first two years of Aquarius 3.0 Level 2 sea surface salinity data we investigate time and space scales of variability and trends. We conduct a statistical validation of Aquarius measurements with Argo in situ observations. Several aspects are considered, including spatial characteristics and temporal agreement, as well as seasonal differences by ocean basin and hemisphere. An exploration of ascending/descending path differences for the Aquarius salinity product is also explored. Regional studies examine the time and space scales of variability through time series comparisons and spatial variogram analysis. Results show that Aquarius validates well with Argo overall, while each metric captures slightly different characteristics of sea surface salinty by region and by considerations over time and space.