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Natural beach shorelines commonly present morphological rhythmic or non‐rhythmic features of varying geometrical characteristics. Traditionally, their formation is believed to be due to wave‐induced processes, a line thoroughly investigated during the last few decades. However, these natural beach formations are frequently bounded by coastal cliffs (or capes) and are affected by intense winds, a fact not previously considered. This paper presents the results of a field survey, demonstrating the existence of atmospheric‐hydrodynamic coupling in the nearshore region outside of the breaking zone at Carchuna beach (Motril, Spain), where the atmospheric conditions are influenced by a lateral geographic obstacle (Cape Sacratif).

RESUMO ABSTRACT: NUMBER OF RAINFALL DAyS FORECASTING FOR THE SOUTHERN HALF OF RIO GRANDE DO SUL USING THE SEA SURFACE TEMPERATURE (SST)This study presents a climate forecasting model of the Number of Rainfall Days (NRD) for some meteorological stations in Rio Grande do Sul using the Sea Surface Temperatures (SST) as the predictable variables. Two sets of data were used in this research: the monthly data of NRD, which were obtained from 5 meteorological stations located in the southern half of Rio Grande do Sul, in the period of 1982 until 2005; and the SST data, measured in the same period. This series was divided in two periods: the dependent period is from 1982 to 2002, and it was used to determine the predictable equations and the regression coefficients; and the independent period, which is from 2003 to 2005, and was used to validate the model. The SST data were employed to establish the relations between the variables through the regression analysis. Good results were obtained in the prediction of the NRD for the regions and all the months analyzed. The predictable and observed data had a very similar distribution of the variables. Although there was some predictable values that differed from the observed ones, but these differences were not significant. The higher differences between the foreseen and the observed values occurred in the independent period.

[1] Ashton and Murray [2006a, 2006b] (henceforth referred to as AM06) showed that coastal evolution can be strongly affected by wave angle when it is formulated in terms of deepwater wave quantities. Most alongshore sediment transport formulae (i.e., CERC formulation) are expressed in terms of the breaking-wave height and the breaking-wave angle. In such formulae, if the breakingwave height is held constant, the alongshore sediment transport is maximized when waves are breaking at an angle of 45°. For breaking-wave angles greater than 45°, the shoreline is unstable [Wang and Le Mehaute, 1980], although it is normally argued that due to wave refraction angles are typically much smaller. AM06 demonstrated that shoreline instability should occur whenever waves approach a shoreline with deep water wave angles greater than approximately 45°, even if breaking-wave angles are much smaller. This process may lead to the self-organization of cuspate shoreline features. We would like to explore the influence of this mechanism in the formation and preservation of the irregular cuspate features along Carchuna beach (southern Spain), as suggested by Ashton and Murray [2004].[2] Carchuna is a 4 km long semireflective beach exhibiting large-scale shoreline features (Figure 1), with a mean alignment W-E [Ortega-Sánchez et al., 2003]. The sediment is very heterogeneous, varying from fine to coarse, and the most energetic wave climate approaches are W, WSW, SW, ESE and E, thus they are strongly oblique to the initially straight shoreline (Figure 1c). AM06 simulations suggest four types of shoreline response depending on the high angle wave climate: migrating alongshore sand waves, cuspate bumps, flying spits and reconnecting spits. The authors controlled the wave climate using two variables (other variables such as wave height are held constant): the fraction of waves approaching from high versus low angles (U) and the wave climate asymmetry (A). Detailed offshore wave climate analysis for Carchuna yields U = 0.92 and A $ 0.5, thus indicating strong obliquity. According to Figure 9 of AM06a the Carchuna shoreline morphology should be characterized by the existence of pronounced cuspate bumps. These authors showed that such features extend in the cross-shore direction with a roughly similar spacing when wave climate is relatively symmetric. Higher U values increase the cross-shore extent of the features and make them more pointed.[3] As a first approach, there is general good agreement between Carchuna large-scale features and the results of the AM06 model, and five cuspate bumps can be found, which extend cross-shore at different distances. Nevertheless, there are some important aspects than are not reproduced by their model: (1) the protruding horns do not have a symmetric shape (Figure 1b, H1 to H5); (2) there is a general alongshore variation of the features shape: from H1 to H5 they change from a generally pointed to curvy shape; (3) the relative orientation of the coastline changes between features (between H1 and H2 the ori...

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