Satellite products performance based on in-situ data to evaluate SST variability in a subtropical inner shelf in Brazil

Abstract

This study compares in-situ, satellite (MODIS Terra and Aqua daytime and nighttime), and reanalysis (Operational Sea Surface Temperature and Sea Ice Analysis – OSTIA) sea surface temperature (SST) data of the inner shelf of Paraná – Brazil at daily scales. There are match-up pairs for all products covering the whole range of in-situ SST (19°C–30°C) and every month, consisting of an appropriate method to validate our satellite datasets in the study area. Although there is a good statistical agreement between MODIS retrievals and in-situ SST, cloud coverage over the study area results in a large number of gaps along with the time series. Thus, dominant features of the SST variability patterns were characterized based on 35 years (1985–2018) of OSTIA SST. There is a strong influence of the Brazil Coastal Current during late winter months contrasting with warmer waters from the Brazil Current during summer. Local high-frequency forcing dominates SST variability, mostly high-energy meteorological events, which act like pulses that intensify mixing processes, resulting in a stair-like variability pattern. At adequate temporal and spatial scales, the relatively cost-effective, spatially explicit, frequent, and continuous remote sensing data can provide the necessary information to support the reliance of our civilization on the ocean. As the SST regime in coastal waters differs from the open waters, the results presented here are unique. They can provide references to understanding the dominant scales of complex coastal dynamics, a key to predict impacts, draw scenarios and mitigate risks, supporting the sustainability of marine and coastal ecosystem services.