Dynamics and Thermodynamics of the Boussinesq North Atlantic Eddy Kinetic Energy Spectral Budget

Statistical characterization of oceanic flows has been a long standing issue; such information is invaluable for formulating hypotheses and testing them. It also allows us to understand the energy pathways within the ocean, which is highly turbulent. Here, we apply the wavelet approach to wavenumber spectral analysis, which has recently been proved to be beneficial in quantifying the spatially heterogeneous and anisotropic nature of oceanic flows. Utilizing an eddy-rich ensemble simulation of the North Atlantic, we are able to examine the spectral transfers of eddy kinetic energy (EKE) and effect of potential energy, here defined via dynamic enthalpy, on the EKE spectral budget. We find that vertical advection of EKE modulates the up- and down-scale direction and strength of EKE spectral flux throughout the North Atlantic domain. The vertical eddy buoyancy flux tends to be small below the mixed layer, suggesting that the flow is largely adiabatic. In maintaining this adiabatic nature, the eddy advection of dynamic enthalpy and practical salinity tend to partially compensate for the eddy advection of potential temperature; this partial cancellation between temperature and salinity is similar to the thermodynamic spice variable. Key Points Continuous wavelet transform is used to diagnose the eddy-kinetic energy (EKE) spectral budget Vertical advection intermittently modulates the direction and strength of EKE spectral cascade throughout the North Atlantic EKE input from eddy advection of potential temperature tends to counteract that of practical salinity and dynamic enthalpy Plain Language Summary Turbulence is defined as a regime where the flow is irregular and chaotic. In other words, it cannot be analytically described nor understood. Oceanic flows fall under this category and we depend on statistical methods to characterize and quantify them. Here, we focus on the North Atlantic Ocean and apply a framework which allows us to examine the statistical features of oceanic turbulence in a spatially local manner, for example, near the Gulf Stream or afar from it. We find that the vertical up- and down-heaval of currents and transport of temperature and salt modulate the turbulent characteristics.