A5046021358- Oceanographic and Atmospheric Processes
- Tropical and Extratropical Cyclones Research
- Climate variability and models
- Geology and Paleoclimatology Research
- Ocean Waves and Remote Sensing
- Marine and coastal ecosystems
- Geological formations and processes
- Meteorological Phenomena and Simulations
- Methane Hydrates and Related Phenomena
- Geophysics and Gravity Measurements
- Fluid Dynamics and Turbulent Flows
- Solar and Space Plasma Dynamics
- Coastal and Marine Dynamics
- Geomagnetism and Paleomagnetism Studies
- Atmospheric and Environmental Gas Dynamics
- Fluid Dynamics and Vibration Analysis
- Arctic and Antarctic ice dynamics
- Computational Fluid Dynamics and Aerodynamics
- Vibration and Dynamic Analysis
- Marine Biology and Ecology Research
- Isotope Analysis in Ecology
- Aeolian processes and effects
- Geological Studies and Exploration
- Nonlinear Dynamics and Pattern Formation
- Geological and Tectonic Studies in Latin America
Stanford University
2015-2024
University of Washington Applied Physics Laboratory
2024
Oregon State University
2024
Shanghai Jiao Tong University
2024
Texas A&M University
2021
University of Mary
2020
University of Maryland, College Park
2020
Woods Hole Oceanographic Institution
2008-2016
Woodwell Climate Research Center
2016
Earth System Science Interdisciplinary Center
2013
Energy in surface ocean currents can dissipate into deep water via enhanced turbulence at the boundaries between masses.
Abstract Many ocean fronts experience strong local atmospheric forcing by down-front winds, that is, winds blowing in the direction of frontal jet. An analytic theory and nonhydrostatic numerical simulations are used to demonstrate mechanism which lead frontogenesis. When a wind blows down front, cross-front advection density Ekman flow results destabilizing wind-driven buoyancy flux (WDBF) equal product transport with surface lateral gradient. Destabilization water column convection is...
Abstract The destruction of potential vorticity (PV) at ocean fronts by wind stress–driven frictional forces is examined using PV flux formalism and numerical simulations. When a front forced “downfront” winds, that is, winds blowing in the direction frontal jet, nonadvective upward sea surface induced. extracts out ocean, leading to formation boundary layer thicker than Ekman layer, with nearly zero nonzero stratification. reduction not only active but transmitted through via secondary...
Abstract The generation and destruction of stratification in the surface mixed layer ocean is understood to result from vertical turbulent transport buoyancy momentum driven by air–sea fluxes stresses. In this paper, it shown that magnitude penetration are strongly modified horizontal gradients momentum. A classic example strong restratification resulting frontogenesis regions confluent flow. Frictional forces acting on a baroclinic current either imposed externally wind stress or caused...
A parameterization is proposed for the effects of symmetric instability (SI) on a resolved front. The dependent external forcing by surface buoyancy loss and/or down-front winds, which reduce potential vorticity (PV) and lead to conditions favorable SI. consists three parts. first part specification vertical eddy viscosity, derived from specified ageostrophic circulation resulting balance Coriolis force Reynolds momentum flux (a turbulent Ekman balance), with previously structure function...
Abstract Lateral stirring is a basic oceanographic phenomenon affecting the distribution of physical, chemical, and biological fields. Eddy at scales on order 100 km (the mesoscale) fairly well understood explicitly represented in modern eddy-resolving numerical models global ocean circulation. The same cannot be said for smaller-scale processes. Here, authors describe major field experiment aimed observing understanding processes responsible 0.1–10 km. Stirring varying intensity were...
The overturning circulation of the global ocean is critically shaped by deep-ocean mixing, which transforms cold waters sinking at high latitudes into warmer, shallower waters. effectiveness mixing in driving this transformation jointly set two factors: intensity turbulence near topography and rate well-mixed boundary are exchanged with stratified interior. Here, we use innovative observations a major branch circulation-an abyssal current Southern Ocean-to identify previously undocumented...
During the winters of 2013–2014 and 2014–2015, anomalously warm temperatures in western North America cool eastern resulted substantial human environmental impacts. Motivated by impacts these concurrent temperature extremes intrinsic atmospheric linkage between weather conditions United States, we investigate occurrence "warm-West/cool-East" surface anomalies, which call "North American winter dipole." We find that, historically, warm-West/cool-East dipole have been associated with anomalous...
Abstract An analysis and physical interpretation of near-inertial waves (NIWs) propagating perpendicular to a steady, two-dimensional, strongly baroclinic, geostrophic current are presented. The is appropriate for currents with order-one Richardson numbers such as those associated fronts experiencing strong, wintertime atmospheric forcing. This work highlights the underlying physics behind properties NIWs using parcel arguments principles conservation density absolute momentum. Baroclinicity...
Winds aligned with geostrophic currents input energy into the ocean circulation. For baroclinic, surface‐intensified currents, winds of this orientation (i.e., down‐front winds) reduce potential vorticity in mixed layer, making flow susceptible to symmetric instability (SI). SI is a submesoscale shear that draws its from currents. High‐resolution numerical simulations are used demonstrate how forced driven by extracts at rate proportional Ekman buoyancy flux, dot product transport and...
Abstract The passage of a winter storm over the Gulf Stream observed with Lagrangian float and hydrographic velocity surveys provided unique opportunity to study how interaction inertial oscillations, front, symmetric instability (SI) shapes stratification, shear, turbulence in upper ocean under unsteady forcing. During storm, rapid rise rotation winds excited motions. Acting on these sheared motions modulate stratification surface boundary layer. At same time, cooling downfront generated...
Abstract Weakly stratified layers over sloping topography can support a submesoscale baroclinic instability mode, bottom boundary layer counterpart to surface mixed instabilities. The results from the release of available potential energy, which be generated because observed intensification turbulent mixing in deep ocean, or Ekman adjustment current on slope. Linear stability analysis suggests that growth rates instabilities comparable those mode and are relatively insensitive topographic...
Layering of ocean velocity “fine structure” has been coherently observed across the entire extent a Gulf Stream warm‐core ring using shipboard acoustic Doppler current profiler system in September 2009 and independently sampled as transited moored array. Lines constant phase generally followed isopycnals they deepened within center. We also clear separation vertical structure flows associated with (of order 0.5 m/s) shorter (200 m) less energetic (~0.2 fine structure, which was further to...
Abstract The dynamics of symmetric instability and two-dimensional inertia–gravity waves in a baroclinic geostrophic flow undergoing frontogenesis is analysed. A frontogenetic strain associated with balanced deformation field drives an ageostrophic circulation temporal variations the basic state that significantly affect properties perturbations to background flow. For stable stratification, result or waves, depending on sign Ertel potential vorticity magnitude Richardson number kinetic...
Abstract A slab mixed layer model and two-dimensional numerical simulations are used to study the generation energetics of near-inertial oscillations in a unidirectional, laterally sheared geostrophic current forced by oscillatory winds. The vertical vorticity ζ g modifies effective Coriolis frequency , which is equivalent local resonant forcing frequency. In addition, velocity response elliptical, not circular, because oscillation periodically exchanges energy with flow via shear...
Abstract Nonconservative processes change the potential vorticity (PV) of upper ocean and, later, through subduction surface waters into interior, affect general circulation. Here we focus on how boundary layer turbulence, in presence submesoscale horizontal buoyancy gradients, generates a source at balance known as turbulent thermal wind. This PV injection can be similar magnitude to fluxes from wind and fluxes, hence lead net onto outcropped isopycnals even during periods loss. The...
The Gulf Stream front separates the North Atlantic subtropical and subpolar ocean gyres, water masses with distinct physical biogeochemical properties. Exchange across is believed to be necessary balance freshwater budget of gyre support biological productivity region; however, mechanisms responsible have been subject long-standing debate. Here, evolution a passive dye released within north wall provides direct observational evidence enhanced mixing front. Numerical simulations indicate that...
Unprecedented quantities of heat are entering the Pacific sector Arctic Ocean through Bering Strait, particularly during summer months. Though some is lost to atmosphere autumn cooling, a significant fraction incoming warm, salty water subducts (dives beneath) below cooler fresher layer near-surface water, subsequently extending hundreds kilometers into Beaufort Gyre. Upward turbulent mixing these sub-surface pockets likely accelerating sea ice melt in region. This Pacific-origin brings both...
Abstract Sections of temperature, salinity, dissolved oxygen, and velocity were made crossing the Gulf Stream in late January 2006 to investigate role frontal processes formation Eighteen Degree Water (EDW), Subtropical Mode North Atlantic. The sections nominally perpendicular stream measured a Lagrangian frame by following floating spar buoy drifting Stream’s warm core. During survey, EDW was isolated from mixed layer stratified seasonal pycnocline, suggesting that not yet actively being...
Over the Texas-Louisiana Shelf in Northern Gulf of Mexico, eutrophic, fresh Mississippi/Atchafalaya river plume isolates saltier waters below, supporting formation bottom hypoxia summer. The also generates strong density fronts, features circulation that are known pathways for exchange water between ocean surface and deep. Using high-resolution observations numerical simulations, we demonstrate how summer land-sea breeze rapid vertical at fronts. We show interaction fronts leads to...