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Dragani W.C.,CONICET | Dragani W.C.,University of Buenos Aires | Cerne B.S.,University of Buenos Aires | Cerne B.S.,CONICET | And 5 more authors.
Dynamics of Atmospheres and Oceans | Year: 2013

In the present paper, the highest wind waves measured at the Río de la Plata mouth were selected to characterize weather patterns associated with the most severe wave conditions in this region. This study was carried out on the basis of wave parameters data series - 14. year long - measured at the Río de la Plata mouth. From the fifteen selected energetic events, twelve were associated with the presence of cyclones located either on the continental shelf (northern 40° S) or on the Uruguayan and southern Brazilian region. On the other hand, three events were linked to the occurrence of post-frontal anticyclones and low pressure systems located in the Southwestern Atlantic Ocean. This last weather pattern is frequently associated with " cold air irruptions" in the Río de la Plata region and, up to the present, it was rarely associated with the presence of the highest waves at the Río de la Plata mouth or adjacent continental shelf. Finally, a common feature observed in almost all the selected cases was the presence of intense wind gusts. This subject is briefly described. © 2013 Published by Elsevier B.V.

Dragani W.C.,Servicio de Hidrografia Naval y ESCM INUN | Dragani W.C.,CONICET | Dragani W.C.,University of Buenos Aires | Martin P.B.,Servicio de Hidrografia Naval y ESCM INUN | And 8 more authors.
Climatic Change | Year: 2013

Several works reported wind-wave climate changes at Buenos Aires Province continental shelf. The aim of this work is to investigate the impact of these changes in the coastal processes of the region. This study is carried out by means of visual wave parameters gathered at the surf zone of Pinamar and by a conveniently implemented and validated numerical wave model (SWAN). Numerical results corresponding to a grid point located 30 km off Pinamar show a significant increase of wave heights from the S and SSE directions and in the frequency of occurrence of waves coming from the S, SSE and E. It is shown that these slight offshore appreciated trends would not have significant effects on the breaker heights observed at the surf zone at Pinamar. On the contrary, the slight positive trend observed offshore in the frequency of occurrence could be affecting the incidence of waves onshore, producing an increase in the number of cases of normal incidence at the surf zone and, consequently, a significant decrease in the alongshore wave energy flux assessed at Pinamar. This reduction in the alongshore wave energy flux could be responsible for some coastal changes detected in the region as, for instance, the remarkable shortening of Punta Rasa spit located 70 km northward Pinamar. © 2013 Springer Science+Business Media Dordrecht.

Martin P.,Servicio de Hidrografia Naval y ESCM INUN | Martin P.,CONICET | Martin P.,University of Buenos Aires | Dragani W.,Servicio de Hidrografia Naval y ESCM INUN | And 9 more authors.
Brazilian Journal of Oceanography | Year: 2012

The performance of NCEP/NCAR I, NCEP/DOE II, JRA-25 and ERA-Interim global databases, implemented as atmospheric forcings of the SWAN model in the Río de la Plata region, was quantitatively tested by calculating the bias, the mean square root error, the determination coefficient and the slope of the line fitted between observed and simulated wave parameters (significant wave height, mean period and direction). Even though statistical estimators showed no evident differences for wave periods and directions some noticeable differences were observed for simulated significant wave heights depending on the forcing used. The lowest bias (0.22 m) was obtained when the SWAN model was forced by ERA-Interim. With regard to the mean square root errors, the lowest values were obtained when NCEP/NCAR I (0.16 m) and NCEP/DOE II (0.19 m) were used as forcing. In addition, the best slope for simulated heights (0.79) was obtained using NCEP/DOE II. Computed determination coefficients for heights, periods and directions were very similar (0.89-0.93) for all the simulations carried out in this study. Energetic and severe wave events were given special consideration. The most energetic wave episode recorded in the Río de la Plata mouth (24 August, 2005) was analyzed and discussed in particular. It was concluded that during energetic atmospheric conditions the best agreement is achieved by implementing NCEP/DOE II as forcing. In the light of these results it is concluded that NCEP/DOE II is the most suitable atmospheric forcing to simulate wave heights with the SWAN model in the Río de la Plata region.

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