Abstract Previously validated model results were used to characterize the wave climate over the Southern Brazilian Shelf (SBS). The low mean significant wave height over the western South Atlantic shelves was shown together with examples of cyclone-induced extreme wave fields and other typical wave conditions. The mean offshore spectra showed a bimodal shape with a predominance of S/SSW and ENE/E waves with distinctive interannual rising periods in wave energy density. Along-shelf wave energy gradients were seen near the coast with higher energy located off capes and coastal projections and energy minima between them. A considerable drop in wave energy suggests the 40 m depth as the mean wave base and consequently the lower limit of the SBS shoreface. The upper shoreface mean wave energy density varied abruptly along the shelf in response to differences in bottom declivities. The large and shallow shoreface was responsible for an intense refraction of the waves and hence very small angles of attack. Additionally, it was shown the sheltering effect caused by capes and coastal projections and a remarkable north/south energy asymmetry between them, caused by a windowing on the wave propagation to the shore. Altogether, it was possible to state that bottom friction plays a major role in wave differentiation along the SBS shoreface, thus suggesting that shelf morphology might indeed be more important to generate wave variability than the offshore wave variation itself.

中文翻译：

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巴西南部大陆架的海洋风波气候学。第二部分：空间和时间的可变性

摘要 先前经过验证的模型结果被用于表征巴西南部大陆架 (SBS) 上空的波浪气候。与气旋引起的极端波场和其他典型波浪条件的例子一起显示了南大西洋西部大陆架的低平均有效波高。平均离岸光谱显示双峰形状，以 S/SSW 和 ENE/E 波为主，波浪能量密度的年际上升周期明显。在海岸附近观察到沿架波能量梯度，较高的能量位于海角和海岸投影以及它们之间的能量最小值。波浪能的显着下降表明 40 m 深度是平均波浪基础，因此是 SBS 岸面的下限。响应于底部坡度的差异，上岸面平均波浪能量密度沿陆架突然变化。大而浅的岸面造成了波浪的强烈折射，因此迎角很小。此外，还显示了由海角和海岸投影引起的遮蔽效应以及它们之间显着的北/南能量不对称，这是由于波传播到海岸的窗口造成的。总而言之，可以说底部摩擦在沿 SBS 海岸面的波浪分化中起主要作用，因此表明陆架形态对于产生波浪变化确实可能比海上波浪变化本身更重要。大而浅的岸面造成了波浪的强烈折射，因此迎角很小。此外，还显示了由海角和海岸投影引起的遮蔽效应以及它们之间显着的北/南能量不对称，这是由于波传播到海岸的窗口造成的。总而言之，可以说底部摩擦在沿 SBS 海岸面的波浪分化中起主要作用，因此表明陆架形态对于产生波浪变化确实可能比海上波浪变化本身更重要。大而浅的岸面造成了波浪的强烈折射，因此迎角很小。此外，还显示了由海角和海岸投影引起的遮蔽效应以及它们之间显着的北/南能量不对称，这是由于波传播到海岸的窗口造成的。总而言之，可以说底部摩擦在沿 SBS 海岸面的波浪分化中起主要作用，因此表明陆架形态对于产生波浪变化确实可能比海上波浪变化本身更重要。