Morning transition case between the land and the sea breeze regimes

Abstract

An experimental field campaign took place in September 2013 near the coastline in the southeastern Campos basin in the island of Mallorca to characterize experimentally the transition between the sea and land breezes and to further study the successful cases with the corresponding high-resolution numerical simulations. Favorable weather conditions were only found for one episode that comprised a well formed nocturnal land breeze, followed by the morning transition to sea-breeze until noon the next day, when incoming clouds switched off the breeze regime. To analyse this transition between land and sea breezes the official network of stations is used, supplemented by a portable station close to the shore and soundings of temperature (taken by a captive balloon and remotely controlled multicopter). These data are used to check the goodness of the corresponding simulation at a horizontal resolution of 1 km. Model and observations see similarly both regimes and the transition, showing some differences in the timing and the details in the surface layer. This transient event is analyzed in terms of phases, going consecutively through land-breeze, phase previous to the sea breeze, when land heating starts but it is still colder than the sea, the preparatory phase when the land becomes warmer than the sea, and the development phase when the breeze front progresses inland.