December 8, 2022 Meteotsunami Along the Southeastern Coast of South America: A Case Study

On December 8th, 2022, a meteotsunami caused significant damage to the southern beaches of Mar del Plata city, Argentina, and the Montevideo Port in Uruguay. The event was observed over a wide area, from Puerto Belgrano in the south of Buenos Aires Province, Argentina, to La Paloma, Uruguay, including locations in the upper Río de la Plata estuary. The meteotsunami was driven by a relatively long perturbation of the surface atmospheric pressure caused by the movement of an elongated high-pressure anomaly running parallel to a low-pressure system associated with an atmospheric frontal zone. The atmospheric perturbation propagated faster than the meteotsunami between Mar del Plata and Montevideo, but both velocities may have been similar between Mar del Plata and Santa Teresita, where the maximum meteotsunami wave height of 0.92 m was recorded, likely due to the Proudman resonance mechanism. The propagation direction of the front from SW to NE partially explains the negligible response of the water level on the Argentinean Río de la Plata coast, where observation sites are close to the shore from where the forcing originates, as well as the almost identical starting time of the water level activity in the upper Río de la Plata and the outer sector of the estuary. This event was different from other past events in the study region, as there was no evidence of atmospheric gravity wave propagation. One significant limitation in understanding the observed atmosphere–ocean interaction in the study region is the nonexistence of high-frequency atmospheric pressure data.