Characteristics of sea breeze in a complex terrain island seen by CERRA

The physical mechanisms underlying sea-breeze (SB) conditions in the Palma basin (Mallorca island, western Mediterranean Sea) are analyzed using the Copernicus European Regional Reanalysis (CERRA) model outputs from 2009-2020. In this complex terrain region, SB is strongly influenced by the upslope winds generated at the mountains that close the basin. The comparison of model results with multiple sources of observations (automatic weather stations AWS, satellite products and radiosondes) shows its ability to reproduce the main SB characteristics. Taking as reference the classification of SB conditions from a previous AWS-based study, a new methodology is now proposed that consists of the application of selecting filters to the CERRA data. The characteristics of the SB events show good agreement with those selected from the AWS. CERRA is able to reproduce the majority of SB patterns: the evolution from land breeze to SB, the cold and moist air advection from the sea during the steady state, the height and intensity of the SB maximum, the importance of the soil moisture and the horizontal and vertical temperature differences. CERRA has difficulties in reproducing SB events which are strongly conditioned by the topography of the basin, due to the insufficient spatial resolution to include the effect of surface heterogeneities, as is the case for upslope winds. However, this method is applicable to other complex terrain regions, and CERRA presents itself as a very useful tool for the study of the physical mechanisms that occur under SB conditions. • Sea breeze is analyzed over a complex terrain island using CERRA from 2009 to 2020. • CERRA is able to statistically reproduce the main sea breeze features. • New sea breeze selecting methodology is proposed for CERRA-like data. • The orography representation in CERRA lacks accuracy to show terrain-induced effects. • Vertical atmospheric structure in CERRA reproduces observations from radiosoundings.