Evaluation of baroclinic effects on mean water levels in Guanabara Bay

ABSTRACT This study analyzes hydrodynamic aspects of the Guabanara Bay estuarine system, which is in the southern coast of the state of Rio de Janeiro, Brazil. Hydrodynamic circulation patterns were characterized, with and without the influence of baroclinic pressure gradients due to water density differences. Typical summer and winter scenarios are considered. The evaluation adopted computational simulations of hydrodynamic circulation, using models from the environmental hydrodynamic base system, entitled SisBaHiA. The simulations indicate that by disregarding baroclinic effects in the pressure gradients, the mean water levels in the Guanabara Bay are underestimated up to 5 centimeters, depending on the region and season of year. However, the hydrodynamic circulation patterns with or without baroclinic pressure gradients are very similar, as shown by the circulation patterns maps in different tidal phases.

摘要 本研究针对位于巴西里约热内卢州南部沿岸的瓜纳巴拉湾（Guabanara Bay）河口系统的水动力特性展开分析。研究对考虑与不考虑由水体密度差异引发的斜压压强梯度影响时的水动力环流格局进行了特征刻画。本次研究考量了典型夏、冬季情景，采用基于环境水动力基础系统SisBaHiA开发的模型开展水动力环流数值模拟。模拟结果表明，若在压强梯度计算中忽略斜压效应，瓜纳巴拉湾不同区域的平均水位将被低估最高达5厘米，偏差程度随区域与季节而异。然而，无论是否考虑斜压压强梯度，水动力环流格局均高度相似，不同潮汐阶段的环流格局地图也证实了这一结论。