Mesoscale to submesoscale wavenumber spectra in Drake Passage

This study discusses the upper-ocean (0‐200m) horizontal wavenumber spectra in the Drake Passage from 13yr of shipboard ADCP measurements, altimeter data, and a high-resolution numerical simulation. At scales between 10 and 200km, the ADCP kinetic energy spectra approximately follow a k 23 power law. The observedflows are more energetic at the surface, but the shape of the kinetic energy spectra is independent of depth. These characteristics resemble predictions of isotropic interior quasigeostrophic turbulence. The ratio of across-track to along-track kinetic energy spectra, however, significantly departs from the expectation of isotropic interior quasigeostrophic turbulence. The inconsistency is dramatic at scales smaller than 40km. A HelmholtzdecompositionoftheADCPspectraandanalysesofsyntheticandnumericalmodeldatashowthat horizontally divergent, ageostrophic flows account for the discrepancy between the observed spectra and predictions of isotropic interior quasigeostrophic turbulence. In Drake Passage, ageostrophic motions appear to be dominated by inertia‐gravity waves and account for about half of the near-surface kinetic energy at scales between 10 and 40km. Model results indicate that ageostrophic flows imprint on the sea surface, accounting for about half of the sea surface height variance between 10 and 40km.

[1]  C. Wunsch,et al.  ECCO version 4: an integrated framework for non-linear inverse modeling and global ocean state estimation , 2015 .

[2]  K. Speer,et al.  Response of the Antarctic Circumpolar Current to atmospheric variability , 2008 .

[3]  Katharina Burger,et al.  Random Data Analysis And Measurement Procedures , 2016 .

[4]  Bo Qiu,et al.  Impact of oceanic-scale interactions on the seasonal modulation of ocean dynamics by the atmosphere , 2014, Nature Communications.

[5]  Nicolas Picot,et al.  Envisat Ocean Altimetry Performance Assessment and Cross-calibration , 2006, Sensors (Basel, Switzerland).

[6]  Dean Roemmich,et al.  The 2004-2008 mean and annual cycle of temperature, salinity, and steric height in the global ocean from the Argo Program , 2009 .

[7]  Raffaele Ferrari,et al.  Interpreting Energy and Tracer Spectra of Upper-Ocean Turbulence in the Submesoscale Range (1–200 km) , 2013 .

[8]  Laurent Roblou,et al.  Post-processing Altimeter Data Towards Coastal Applications and Integration into Coastal Models , 2011 .

[9]  R. Pinkel.  Vortical and Internal Wave Shear and Strain , 2014 .

[10]  Kathleen A. Donohue,et al.  Wavenumber Spectrum in the Gulf Stream from Shipboard ADCP Observations and Comparison with Altimetry Measurements , 2010 .

[11]  W. Munk.  9 Internal Waves and Small-Scale Processes , 2005 .

[12]  Jonathan Gula,et al.  Seasonality in submesoscale turbulence , 2015, Nature Communications.

[13]  F. Birol,et al.  Estimating boundary currents from satellite altimetry: A case study for the east coast of India , 2008 .

[14]  Dake Chen,et al.  Global Wavenumber Spectrum with Corrections for Altimeter High-Frequency Noise , 2015 .

[15]  C. Wunsch.  Baroclinic Motions and Energetics as Measured by Altimeters , 2013 .

[16]  A. Bennett,et al.  TOPEX/POSEIDON tides estimated using a global inverse model , 1994 .

[17]  J. Sprintall,et al.  Seasonal variability of upper ocean heat content in Drake Passage , 2012 .

[18]  R. Watts,et al.  cDrake: Dynamics and Transport of the Antarctic Circumpolar Current in Drake Passage , 2012 .

[19]  C. Estournel,et al.  Aspects of the seasonal variability of the Northern Current (NW Mediterranean Sea) observed by altimetry , 2010 .

[20]  Worth D. Nowlin,et al.  Structure and Transport of the Antarctic Circumpolar Current at Drake Passage from Short-Term Measurements , 1977 .

[21]  D. Menemenlis,et al.  On the formulation of sea-ice models. Part 1: Effects of different solver implementations and parameterizations , 2010 .

[22]  Russ E. Davis,et al.  Red noise and regime shifts , 2003 .

[23]  R. Ferrari,et al.  The distribution of eddy kinetic and potential energies in the global ocean , 2010 .

[24]  David Griffin,et al.  The SARAL/AltiKa Altimetry Satellite Mission , 2015 .

[25]  A. Mahadevan,et al.  Submesoscale processes and dynamics, In: Ocean Modeling in an Eddying, Regime (AGU Monograph), M. Hecht and H. Hasumi (Eds.) , 2008 .

[26]  Amit Tandon,et al.  Submesoscale Processes and Dynamics , 2013 .

[27]  Chris Henze,et al.  Investigating solution convergence in a global ocean model using a 2048-processor cluster of distributed shared memory machines , 2007, Sci. Program..

[28]  J. Bendat,et al.  Random Data: Analysis and Measurement Procedures , 1971 .

[29]  Hiroyasu Hasumi,et al.  Ocean modeling in an eddying regime , 2008 .

[30]  Craig M. Lee,et al.  Statistics of vertical vorticity, divergence, and strain in a developed submesoscale turbulence field , 2013 .

[31]  P. Thibaut,et al.  Investigating Short-Wavelength Correlated Errors on Low-Resolution Mode Altimetry , 2014 .

[32]  J. LaCasce.  Surface Quasigeostrophic Solutions and Baroclinic Modes with Exponential Stratification , 2012 .

[33]  W. Blumen,et al.  Uniform Potential Vorticity Flow: Part II. A Model of Wave Interacions. , 1978 .

[34]  R. Salmon,et al.  Geophysical Fluid Dynamics , 2019, Classical Mechanics in Geophysical Fluid Dynamics.

[35]  G. Dibarboure,et al.  Do Altimeter Wavenumber Spectra Agree with the Interior or Surface Quasigeostrophic Theory , 2008 .

[36]  T. Chereskin,et al.  Observations of Ekman Currents in the Southern Ocean , 2008 .

[37]  C. Provost,et al.  Computation of Geostrophic Streamfunction, Its Derivatives, and Error Estimates from an Array of CPIES in Drake Passage , 2014 .

[38]  Jerome A. Smith.  Vorticity and Divergence of Surface Velocities Near Shore , 2008 .

[39]  M. Mazloff,et al.  Vertical structure and transport of the Antarctic Circumpolar Current in Drake Passage from direct velocity observations , 2011 .

[40]  Stephen G. Yeager,et al.  Diurnal to decadal global forcing for ocean and sea-ice models: The data sets and flux climatologies , 2004 .

[41]  S. Lentz,et al.  Classical tidal harmonic analysis including error estimates in MATLAB using T_TIDE , 2002 .

[42]  J. Sprintall,et al.  Mean jets, mesoscale variability and eddy momentum fluxes in the surface layer of the Antarctic Circumpolar Current in Drake Passage , 2007 .

[43]  A. Wallcraft,et al.  Inferring dynamics from the wavenumber spectra of an eddying global ocean model with embedded tides , 2012 .

[44]  H. Bryden,et al.  POLEWARD HEAT FLUX AND CONVERSION OF AVAILABLE POTENTIAL ENERGY IN DRAKE PASSAGE , 1979 .

[45]  Lynne D. Talley,et al.  A New Algorithm for Finding Mixed Layer Depths with Applications to Argo Data and Subantarctic Mode Water Formation , 2009 .

[46]  M. P. Chidichimo,et al.  Baroclinic Transport Time Series of the Antarctic Circumpolar Current Measured in Drake Passage , 2014 .

[47]  J. Marshall,et al.  Scales, Growth Rates, and Spectral Fluxes of Baroclinic Instability in the Ocean , 2011 .

[48]  James C. McWilliams,et al.  Mesoscale to submesoscale transition in the California current system. Part III: Energy balance and flux , 2008 .

[49]  R. Ferrari,et al.  Wave–vortex decomposition of one-dimensional ship-track data , 2014, Journal of Fluid Mechanics.

[50]  Yongsheng Xu,et al.  The Effects of Altimeter Instrument Noise on the Estimation of the Wavenumber Spectrum of Sea Surface Height , 2012 .

[51]  L. Perelman,et al.  A finite-volume, incompressible Navier Stokes model for studies of the ocean on parallel computers , 1997 .