Resumen en Inglés:

ABSTRACT This article presents a real-time drifter tracking system designed to investigate circulation and transport processes in coastal environments. Field demonstrations were conducted in two contrasting Brazilian coastal regions: Florianópolis Island in the south, a microtidal area driven primarily by wind circulation, and São Marcos Bay in the northeast, an estuary complex characterized by strong tidal forcing. Surface Velocity Program (SVP) drifters were adapted for coastal applications, incorporating a reel to adjust drogue depth and electronic systems housed in a 3D-printed enclosure. The tracking system was also tested with an undrogued iSphere drifter to assess estuarine surface circulation. Satellite communication systems enabled real-time tracking for efficient deployment and recovery of drifters, while optional fast-response loggers ensured near-continuous data collection. Results revealed rapid circulation responses to wind forcing north of Florianópolis Island, and a tidal-dominated environment in São Marcos Bay, with secondary influence from wind and waves. The real-time tracking system prevented equipment loss and enhanced data acquisition. This reusable drifter setup offers a practical solution for oceanographic studies, supporting repeated deployments, streamlined data collection, and adaptability to various coastal applications and drifter types.

Resumen en Inglés:

ABSTRACT This study uses 21 years (2004-2024) of water level measurements carried out by the IBGE’s Brazilian Continuous Monitoring Network (RBMC), in association with the Global Sea Level Observing System (GLOSS), with the aim of quantifying the temporal variability of the water level, identifying long-term trends in mean sea level, and determining the present spatial extent of tidal inundation of the suburban areas of Salvador. Harmonic, statistical, and spectral analyses, complemented by numerical modeling of the hydrodynamics, show that the sea level is rising at a rate of 2.15 mm/yr and the inundation time is increasing. Important seasonal variability is observed, with higher mean sea levels occurring in April and May driven mainly by the wind stress, whose interannual variation also causes alternating interannual MSL trends. The data indicate an increase in the frequency and severity of extreme high sea level events, regularly associated with the passage of subtidal waves that have become higher and more frequent over the years. Numerical simulations showed that subtidal oscillations tend to be amplified inside the estuary, likely increasing the severity of inundation events. A suburban area of 0.497 km2 along the bay margin of Salvador, with poor infrastructure, experiences more intense tidal inundation approximately every 4.4 years.