SEA BREEZE CLIMATOLOGY IN URUGUAY
Gastón Manta, Marcelo Barreiro y Madeleine Renom
The sea breeze is a mesoscale circulation on the coast driven by the differential heating between the land and sea. Here, the sea breeze in Uruguay is characterized using data of 8 coastal meteorological stations, as well as satellite and reanalyses data sets in the period 2011-2016. A sea breeze identification index was developed using wind speed and direction at 08:00 and 16:00 local time. An average of 60 days per year was found, ranging between 51 and 71 days. Sea breeze occurs twice as often in summer, and February and March show the largest variability in the number of days with sea breeze. The sea breeze develops for sea level pressure values ranging between 1000 and 1023 hPa, weak synoptic pressure gradient, and predominance of clear skies. Consecutive days with breeze (2-7 days) are usually associated with the passage of high pressure systems in the southwestern Atlantic or with atmospheric blocking. When there is sea breeze, it tends to occur along the entire Uruguayan coast. Nonetheless, there are differences in sea breeze development between the estuary and the oceanic regions due to the differences in air-sea coupling and the orientation of the coast in relation to the prevailing northeasterly winds. On average, the sea breeze starts at 11:00 (12:00) local time in the oceanic (estuarine) coast and has a southeasterly (southerly), reaching a maximum speed of 7.1 m.s-1 near 16:00. In several cases with sea breeze, cumulus-type cloudiness can be distinguished associated with the breeze front.