Meteorol Atmos Phys (2003) DOI 10.1007/s00703-002-0579-1 Meteorology and Air Quality Group, Wageningen University, Wageningen, The Netherlands Impacts of topography and land degradation on the sea breeze over eastern Spain J.-F. Miao  , L. J. M. Kroon, J. Vila `-Guerau de Arellano, and A. A. M. Holtslag With 9 Figures Received February 25, 2002; accepted October 7, 2002 Published online: April 10, 2003 # Springer-Verlag 2003 Summary A three-dimensional non-hydrostatic atmospheric model RAMS, version3b, is used to examine the impact of complex topography on the sea breeze under heterogeneous and degradation land use characteristics. In the study, it is shown that topography plays an important role in the sea-breeze circulation by aligning the sea breeze front to the coastline and locating the convergence zones close to the mountain range. When the sea breeze is coupled with the upslope wind, the sea-breeze circulation is strengthened by the topography. Sensitivity analyses are carried out to determine the influ- ence of vegetation and soil moisture, i.e., land surface mod- ifications, to this thermally driven flow. Land degradation results in an enhanced sea-breeze circulation which is char- acterized by a stronger onshore flow, a stronger return current, a larger updraft velocity associated with the sea-breeze front and further inland penetration. Other important features are a deeper sea-breeze depth, a larger downdraft velocity behind the sea-breeze front, and a longer offshore extent. The results also show how land changes modify the sea breeze temporal evolution resulting in an earlier onset and later end. The study stresses the convenience of using three-dimensional models with detailed land surface information to model the sea breeze in complex terrain where land use is rapidly modified. 1. Introduction The sea breeze is a common mesoscale phenom- enon during the summer months in many coastal areas, and has been observed and documented since ancient times (see Neumann, 1973). During the last half century, considerable research has been devoted to observational, theoretical, and numerical modeling of the sea breeze (e.g., Atkinson, 1981; Pielke, 1984; Abbs and Physick, 1992; Simpson, 1994; Tijm et al, 1999b). Never- theless, the sea breeze is still an interesting subject of study because of its importance to human affairs, its role in air pollution transport and pre- cipitation, and its fascinating structure, which de- pends on synoptic, and boundary-layer dynamics. Arid and semiarid regions are very sensitive to a variety of physical, chemical and biological degradation processes, collectively known as ‘‘desertification’’. The Mediterranean regions, such as the Iberian Peninsula, are particularly vulnerable to desertification. A preliminary mod- eling study over Spain has shown that precip- itation patterns are sensitive to land surface characteristics, in particular the soil moisture (Moene et al, 1995). In recent years, a series of international experimental studies, e.g., the EFEDA (European Field Experiment in a Desert- ification Threatened Area) experiment (Bolle et al, 1993), have provided data to improve land surface descriptions in semiarid areas subject to desertification. Also, some meteorological mod- els including interactive vegetation schemes  Current address: Department of Earth Sciences, Go ¨teborg University, Sweden.