ORIGINAL PAPER A climatological study of the influence of synoptic-scale flows on sea breeze evolution in the Bay of Alicante (Spain) C. Azorin-Molina & D. Chen Received: 2 July 2007 / Accepted: 13 March 2008 # Springer-Verlag 2008 Abstract The focus of this study is on sea breeze (SB) characteristics during May and August in the Bay of Alicante (south-eastern coast of the Iberian Peninsula, IP, Spain) for the period 2000–2005 in relation to dominating synoptic-scale winds. A dataset containing 292 SB events was objectively constructed to study the impact of the daily synoptic winds at 850 hPa on the main characteristics of SBs. The winds were used to designate three major synoptic-scale regimes: offshore, onshore, and coast-parallel flows. The SB features examined include mean lag of the SB passage, wind speed and direction at the time of onset, mean lag of SB cessation, mean duration of SB, mean maximum velocity, and inland propagation of SB. Some of the characteristics had not been previously considered in the literature. It is found that in comparison with onshore synoptic flows, offshore favors the delayed arrival and termination of SBs, resulting in a longer mean duration. Further, they produce the most intense passages, cause a more frequent southeasterly component, and result in a higher SB gust speed and shorter mean inland penetration. Results from coast-parallel flows are also presented. The strength of the large-scale flows plays a major role upon SB parameters, which essentially support other numerical modeling results. 1 Introduction SBs are controlled by local and regional environmental factors influencing their development, evolution, and characteristics. Carnesoltas (2002) classified these factors into two main categories: (a) geographical-physical factors such as latitude (Yan and Anthes 1986), season, shape- curvature (convex or concave) and coastline orientation (McPherson 1970), distance between opposite coasts (Haurwitz 1947), land–sea boundary, depth of water, topography (Kusuda and Alpert 1983; Darby et al. 2002; Miao et al. 2003), land use (Baker et al. 2001; Miao et al. 2003), surface roughness, thermo-conductive and transmitter properties of terrain, and (b) meteorological, hydrological and oceanic factors such as direction and strength of the synoptic-scale flow, stability of the air mass (low level inversions), cloud cover, soil moisture, swell types and stream of water, and sea surface temperature (SST), (Bowers 2004). The first category is static or changes very slowly, whereas the second one alters within a few days and the meteorological parameters vary from day to day or even from hour to hour. SBs are primarily driven by local sea and land air temperature difference (ΔT), which is directly related to pressure difference. Previous SB studies have shown that SB intensity is directly proportional to local solar radiation. Mesoscale environmental factors other than ΔT have nonetheless been found to play a major role in controlling SB characteristics (Borne 1998). The overlying synoptic- Theor Appl Climatol DOI 10.1007/s00704-008-0028-2 C. Azorin-Molina (*) The CEAM Foundation (Fundación Centro de Estudios Ambientales del Mediterráneo), Parque Tecnológico, Charles R. Darwin 14, 46980 Paterna, Valencia, Spain e-mail: cazorin@ceam.es C. Azorin-Molina Group of Climatology, University of Barcelona, Montalegre 6, 08001 Barcelona, Catalonia, Spain D. Chen Regional Climate Group, Department of Earth Sciences, Göteborg University, 405 30 Göteborg, Sweden