A coastal city on the South Pacific Ocean. Urban front and sea-land breeze in Viña del Mar, Chile.

Chile has an extensive coastline on the Pacific Ocean, where important urban areas are located. Approximately 20% of the country's population resides in Coastal Metropolitan Areas. Among these is the Valparaíso-Viña del Mar Metropolitan Area (AMVV), which is home to one million inhabitants. Within this area, Población Vergara (PV) in Viña del Mar stands out for its proximity to the sea and its urban configuration, characterized like a open high buildings zone, intense daytime urban activity and a notable presence of vegetation and trees. This sector has a streets front open to the ocean, which directly influences the air circulation in its interior. To evaluate the both impact urban morphology and frontline buildings on air flow of the sea land breeze (SLB) to Poblacion Vergara, field measurements were taken in the spring at pedestrian level at three times of day: 10 am, 2pm and 8pm, as well as simulations with the ENVI-met software. The results showed that the urban configuration significantly influences the dynamics of the sea breeze, affecting both its entry and exit from the built-up area depending on the time of day. The presence of buildings, streets and vegetation determines the behavior of the air at the sea edge of the city, modifying its velocity both horizontally and vertically; high-rise buildings zone generates accelerations in air flow towards the interior of the city, while wooded vegetation contributes to mitigate these effects. These results are an advance in knowledge regarding the potential cooling and air renewal provided by the ocean in urban areas to mitigate the effects of urban heat.