Satellite-observed sea surface salinity: real trends or instrumental drifts?

Abstract

Monitoring global water cycle intensification through satellite sea surface salinity (SSS) requires distinguishing genuine geophysical trends from instrumental artifacts. This work analyses eight years (2011–2018) of uncorrected SMOS observations to address this problem without relying on external reference datasets. By fitting independent linear regressions for each combination of geographic and antenna-frame coordinates, antenna-frame consistency (trend invariance across the instrument’s field of view) is used as the primary diagnostic for signal separation. Trend significance is assessed via a Student’s T test at the 95% confidence level. An exploratory classification of ocean cells within ±60◦ latitude identifies 52.7% as geophysical trends and 23.5% as instrumental artifacts, with the remainder being inconclusive or statistically non-significant. These results demonstrate that antenna-frame analysis recovers genuine geophysical variability that can be dismissed as noise or removed by standard bias correction and filtering procedures