English

Alexander Soloviev,Atsushi Fujimara,Silvia Matt

doi:10.5670/oceanog.2015.14

English

Alexander Soloviev, Atsushi Fujimara + Show 1 more

Open Access

https://doi.org/10.5670/oceanog.2015.14

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Journal: Oceanography	Publication Date: Mar 1, 2015
Citations: 22	License type: cc-by

Affiliation: Nova Southeastern University

Abstract

Abstract : Convective rains in the Intertropical Convergence Zone produce lenses of freshened water on the ocean surface. Due to significant density differences between the freshened and saltier seawater, strong pressure gradients develop, resulting in lateral spreading of freshwater lenses in the form of gravity currents. Gravity currents inherently involve three-dimensional dynamics. As a type of organized structure, gravity currents may also interact with, and be shaped by, the ambient oceanic and atmospheric environment. Among the important environmental factors are background stratification and wind stress. Under certain conditions, a resonant interaction between a propagating freshwater lens and internal waves in the underlying halocline (the barrier layer) may develop, while interaction with the wind stress may produce an asymmetry in the freshwater lens and associated mixing. These two types of interactions working in concert may explain the series of sharp frontal interfaces observed in association with freshwater lenses during the Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment (TOGA COARE). We conducted a series of numerical simulations using computational fluid dynamics tools. These numerical experiments were designed to elucidate the relationship between vertical and horizontal fluxes of salinity under various environmental conditions and the potential impact of these fluxes on the barrier layer and Aquarius and Soil Moisture and Ocean Salinity (SMOS) satellite image formations.

Highlights

Buoyancy-driven surface currents, such as propagating rain-formed lenses or plumes, are an important component of the tropical ocean environment in the Intertropical Convergence Zone (ITCZ; see, e.g., Wijesekera et al, 1999)
Wall-Adapting Local Eddy-Viscosity (WALE) is optimized for rigid-lid boundary conditions; it results in excessive surface drift velocity when wind stress is applied at the top of the numerical tank due to absence of surface waves
Interaction of Freshwater Plume with Wind Stress we investigated the case of a freshwater plume interacting with wind stress in a nonstratified environment

Summary

Introduction

Buoyancy-driven surface currents, such as propagating rain-formed lenses or plumes (we use these terms interchangeably), are an important component of the tropical ocean environment in the Intertropical Convergence Zone (ITCZ; see, e.g., Wijesekera et al, 1999). Gravity currents may interact with ambient stratification in a resonant way, leading to fragmentation of the near-surface lens, and with the surface wind stress, resulting in lens asymmetry in structure and mixing (Simpson, 1987; Soloviev and Lukas, 1997; Matt et al, 2014). For example, a halocline representing the barrier layer (Lukas and Lindstrom, 1991), can be added to the model during initialization, and wind stress can be applied at the top of the tank.

Results

Conclusion