A Sea-Breeze Case Study in the La Plata River Region Using Local Observations, Satellite Images, and Model Simulations
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A Sea‑Breeze Case Study in the La Plata River Region Using Local Observations, Satellite Images, and Model Simulations Guillermo J. Berri1 · Mariana Dezzutti1 Received: 7 October 2019 / Accepted: 9 July 2020 © Springer Nature B.V. 2020
Abstract Two well-developed sea-breeze cases in the La Plata River region, selected from a 5-month summer period, are studied using local observations, satellite images, and hydrostatic boundary-layer model simulations. Both the northern and southern coast cases are characterized by offshore regional flow that help develop stronger sea breezes due to enhanced horizontal convergence by the opposing flow. The study shows that the sea-breeze propagation accompanies changes in the three-dimensional circulation within the boundary layer. The inland propagation speed of the cloud bands evident in satellite imagery is simulated relatively well by the model’s progression of maximum vertical motion in both cases. Local coastline features affect the inland penetration of the sea-breeze fronts. The inland propagation speed of the surface sea-breeze front estimated with the model simulations is greater than the speed of the cloud bands aloft. Keywords Case study · La Plata River · Modelling · Observations · Sea-breeze circulation
1 Introduction The sea–land breeze is a mesoscale circulation usually observed in meteorological stations near coasts, because of the daily cycle of the surface temperature contrast between land and water. The difference of heat capacities between these surfaces gives rise to the formation of a low-level temperature gradient across the coast that results in the creation of a pressure gradient perpendicular to the coastline. The increase in magnitude of the pressure gradient creates a wind component from water to land, which prevails until late in the afternoon. At night, the local wind component reverses and the land breeze develops, although it is normally weaker than the sea breeze (Simpson 1994). This mesoscale circulation is well defined during the day, so that the three-dimensional structure of the sea breeze can be schematically described as an alongshore vertical cell in which the air at low levels flows from water to land near the coast. The shallow wedge of cooler and humid maritime air moves inland tens of kilometres, creating a sea-breeze front * Guillermo J. Berri [email protected] 1
Facultad de Ciencias Astronómicas y Geofísicas – CONICET, Universidad Nacional de La Plata, Paseo del Bosque s/n, B1900FWA, La Plata, Argentina
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at its leading edge and forcing updrafts, accompanied by local changes of wind, temperature, and humidity patterns (Miller et al. 2003). In order to keep the system in balance, a weaker return flow establishes aloft and an extended subsidence region over the sea closes the cell (Simpson 1994). The sea-breeze circulation occurs in interaction with the regional environment and is conditioned by different factors, for example geography and topography (Miao et al. 2003; Bast
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