Non-tidal ocean loading from Río de la Plata storm surges: empirical modeling at the Argentine–German Geodetic Observatory (AGGO) over its first decade of operation

Frequent storm surges in the Río de la Plata estuary produce non-tidal ocean loading signals detectable at the Argentine–German Geodetic Observatory (AGGO), affecting the space geodetic and gravimetric techniques co-located at the site. An empirical model of water level variations across the estuary is developed for the period 2016–2025, covering the first decade of operation of AGGO, using observations from seven tide gauge stations distributed along the Río de la Plata, complemented by two modeled stations derived from astronomical tidal predictions and a global storm surge model. The storm surge propagation is characterized using the tidal propagation parameters from the Simplified Empirical Astronomical Tide (SEAT) model, and the gravimetric effect and elastic crustal displacements are computed with SPOTL (Some Programs for Ocean-Tide Loading) software. The resulting gravimetric effect series ranges between −14.7 and +18.8 nm s−2, while the vertical displacement ranges between −7.0 and +5.5 mm, with smaller horizontal displacements in the East and North components. The loading-effect correction is validated against the International Geodynamics and Earth Tide Service (IGETS) Level-3 gravimetric residuals from the SG038 instrument at AGGO for the period January 2016 – October 2022. A wavelet analysis applied to the gravimetric residuals reveals spectral power reductions of up to 70% in the 1–12 day period band associated with storm surge activity. The 10-year time series of gravimetric effect and crustal displacements produced in this study provides, for the first time, a continuous correction dataset for the geodetic techniques co-located at AGGO, contributing to improved station coordinate repeatability and to the realization of terrestrial reference frames in the Southern Hemisphere.