Gravity currents in oceanic and estuarine systems: A comprehensive review [version of record]

Abstract Global ocean dynamics involve the large-scale flow and circulation of the world’s oceans, which are essential for regulating heat distribution, sequestering carbon, recycling nutrients, and influencing global weather patterns. Of particular interest in this review paper is the interaction between counterflowing currents, which frequently occur in estuaries and deep-sea environments, and have significant implications for oceanic and estuarine dynamics. When counterflowing currents, including but not limited to gravity currents, develop within the same region and encounter each other, these interactions lead to complex flow dynamics characterized by fronts, eddies, and intense turbulence, which in turn initiate vertical nutrient transport and mixing processes. In addition to affecting both regional and global thermohaline circulation, these interactions play an important role in turbulent mixing, sediment dynamics, and biological productivity. By synthesizing existing studies on counterflowing currents interactions, this paper explains the complex processes that control these phenomena and their significance in oceanic and estuarine environments. We highlight relevant gaps in existing knowledge and suggest future research approaches to advance the understanding of these important oceanic processes.