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A sea breeze is a thermally driven circulation that occurs along coastlines of seas and large lakes, particularly during spring and summer when the temperature contrast between land and water is greatest. This local phenomenon follows a daily cycle, beginning with thin layers (~50m) at dawn and expanding up to 400m as the day progresses (EUMeTrain, 2014). Although typically weaker than synoptic winds, sea breezes are highly predictable due to their cyclical nature (Rojas Gregorio, Cabrera, & Bueso, 2016).
As the land heats up under sunlight, the warm air rises, creating a low-pressure zone. Cooler, denser air from the sea then moves inland, forming the breeze. At night, this circulation can reverse, resulting in land breezes.
Sea breezes occur due to the differential heating of land and water, with water having a higher specific heat capacity, meaning it absorbs and stores energy from the sun more efficiently than land. As a result, water heats and cools more slowly, while land heats rapidly, affecting only its surface layer. This results into greater land daytime and nightie temperature fluctuations.
The sea breeze consists of two opposing flows: cooler air moves inland at the surface (sea breeze), while a return flow moves aloft (see Figure 1). As the land heats, a thermal low-pressure zone forms, drawing in cooler, denser air from the sea, which displaces the warmer, less dense air over the land upward. At altitudes of 1000-1500 meters, the air cools, flows back over the ocean, and sinks, increasing surface-level high pressure. This circulation can lead to temperature drops of 8-11°C, clearer skies, increased humidity, and changes in wind speed and direction.
While most commonly associated with oceans, sea breezes can also occur around large lakes. The reverse process, known as a land breeze, occurs at night but is generally weaker due to reduced vertical motion and smaller temperature gradients.
Formation of the sea breeze. Source: https://www.noaa.gov/jetstream/ocean/sea-breeze
The occurrence and intensity of sea breezes are strongly influenced by seasonal, latitudinal, and daily factors.
In tropical and subtropical coastal areas, sea breezes are common year-round, providing a welcome cooling effect. In higher latitudes, they primarily occur during spring and summer when clear skies, strong sunlight, and maximum temperature contrasts between land and sea are present. Sea breezes typically begin in the late morning, reach their peak in the afternoon, and diminish by evening.
The development of a sea breeze requires a sufficient temperature contrast between land and sea. This is distinct from coastal convergence, where differential friction between land and sea plays a key role.
The shape of the coastline can also influence sea breeze formation. For instance, when sea breezes converge from both sides of a peninsula, convection intensifies. In contrast, sea breezes in areas near bays often diverge, promoting low-level air descent. Other factors, such as temperature gradients, coastal geography, and synoptic weather patterns, also affect sea breeze strength and extent.
Accurate modeling of local wind patterns, such as sea breezes, is essential for optimizing wind energy production in coastal areas. At Vortex, we use the Weather Research and Forecasting (WRF) model to simulate mesoscale and microscale wind behaviour with high precision. Sea breezes, a well-documented mesoscale phenomenon, can boost energy yield in coastal wind farms by utilizing daily wind fluctuations.
By predicting the onset and intensity of sea breezes, we help developers optimize turbine placement, improve energy output, and minimize operational issues like turbulence and wake effects. A high-resolution numerical weather model is able to capture the details of the sea breeze (Schmidt et al., 2022). Figure 2 illustrates wind flow from the sea toward land, based on one of our microscale products, BLOCKS.
Sea breeze in Barcelona coastal area. Source: Vortex
National Oceanic and Atmospheric Administration, NOAA (2023). The Sea Breeze. https://www.noaa.gov/jetstream/ocean/sea-breeze
EUMeTrain. (2014). Sea Breeze. https://resources.eumetrain.org/satmanu/CMs/SB/index.htm
Rojas Gregorio, Jose & Cabrera, Barbara & Bueso, Jordi. (2016). The potential of the sea breeze for wind energy generation in peri-urban coastal areas using small wind turbines.
Schmidt, J., Cañadillas, B., Tindal, A., Meyer Forsting, A., Söderberg, S., & Reiche, K. (2022). Validation of a revised low and moderate wind site classification scheme. Wind Energy Science, 7(3), 815-835. https://doi.org/10.5194/wes-7-815-2022
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