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Patrice
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ArticleGlobal estimates of the energy transfer from the wind to the ocean, with emphasis on near-inertial oscillations(American Geophysical Union, 2019-07-03) Flexas, M. Mar ; Thompson, Andrew F. ; Torres, Hector S. ; Klein, Patrice ; Farrar, J. Thomas ; Zhang, Hong ; Menemenlis, DimitrisEstimates of the kinetic energy transfer from the wind to the ocean are often limited by the spatial and temporal resolution of surface currents and surface winds. Here we examine the wind work in a pair of global, very high‐resolution (1/48° and 1/24°) MIT general circulation model simulations in Latitude‐Longitude‐polar Cap (LLC) configuration that provide hourly output at spatial resolutions of a few kilometers and include tidal forcing. A cospectrum analysis of wind stress and ocean surface currents shows positive contribution at large scales (>300 km) and near‐inertial frequency and negative contribution from mesoscales, tidal frequencies, and internal gravity waves. Larger surface kinetic energy fluxes are in the Kuroshio in winter at large scales (40 mW/m2) and mesoscales (−30 mW/m2). The Kerguelen region is dominated by large scale (∼20 mW/m2), followed by inertial oscillations in summer (13 mW/m2) and mesoscale in winter (−12 mW/m2). Kinetic energy fluxes from internal gravity waves (−0.1 to −9.9 mW/m2) are generally stronger in summer. Surface kinetic energy fluxes in the LLC simulations are 4.71 TW, which is 25–85% higher than previous global estimates from coarser (1/6–1/10°) general ocean circulation models; this is likely due to improved representation of wind variability (6‐hourly, 0.14°, operational European Center for Medium‐Range Weather Forecasts). However, the low wind power input to the near‐inertial frequency band obtained with LLC (0.16 TW) compared to global slab models suggests that wind variability on time scales less than 6 hr and spatial scales less than 15 km are critical to better representing the wind power input in ocean circulation models.
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ArticleA near-inertial mode observed within a Gulf Stream warm-core ring(John Wiley & Sons, 2013-04-08) Joyce, Terrence M. ; Toole, John M. ; Klein, Patrice ; Thomas, Leif N.Layering of ocean velocity “fine structure” has been coherently observed across the entire extent of a Gulf Stream warm-core ring using a shipboard acoustic Doppler current profiler system in September 2009 and independently sampled as the ring transited a moored array. Lines of constant velocity phase generally followed isopycnals as they deepened within the ring center. We also observed a clear separation of the vertical structure of the flows associated with the ring (of order 0.5 m/s) with the shorter (200 m) and less energetic (~0.2 m/s) flows of the velocity fine structure, which was further observed to rotate clockwise with increasing depth, consistent with downward propagating near-inertial waves (NIWs). Observations are consistent with a ring-scale NIW packet, probably wind forced, that shows enhanced NIW energy within the sloping pycnocline at depths of 300–700 m. Evidence of wind-forced NIWs within anticylonic eddies in a numerical simulation shows some similar features to our observations, which we try to understand physically with basic WKB-type wave/current dynamics along the lines of previously published work and a new calculation of NIW trapping within an isolated, baroclinic vortex.
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ArticleSEASTAR: A mission to study ocean submesoscale dynamics and small-scale atmosphere-ocean processes in coastal, shelf and polar seas(Frontiers Media, 2019-08-13) Gommenginger, Christine ; Chapron, Bertrand ; Hogg, Andy ; Buckingham, Christian ; Fox-Kemper, Baylor ; Eriksson, Leif ; Soulat, Francois ; Ubelmann, Clement ; Ocampo-Torres, Francisco ; Nardelli, Bruno Buongiorno ; Griffin, David ; Lopez-Dekker, Paco ; Knudsen, Per ; Andersen, Ole ; Stenseng, Lars ; Stapleton, Neil ; Perrie, Will ; Violante-Carvalho, Nelson ; Schulz-Stellenfleth, Johannes ; Woolf, David K. ; Isern-Fontanet, Jordi ; Ardhuin, Fabrice ; Klein, Patrice ; Mouche, Alexis ; Pascual, Ananda ; Capet, Xavier ; Hauser, Daniele ; Stoffelen, Ad ; Morrow, Rosemary ; Aouf, Lotfi ; Breivik, Øyvind ; Fu, Lee-Lueng ; Johannessen, Johnny A. ; Aksenov, Yevgeny ; Bricheno, Lucy ; Hirschi, Joel ; Martin, Adrien C. H. ; Martin, Adrian P. ; Nurser, A. J. George ; Polton, Jeff ; Wolf, Judith ; Johnsen, Harald ; Soloviev, Alexander ; Jacobs, Gregg A. ; Collard, Fabrice ; Groom, Steve ; Kudryavtsev, Vladimir ; Wilkin, John L. ; Navarro, Victor ; Babanin, Alexander ; Martin, Matthew ; Siddorn, John ; Saulter, Andrew ; Rippeth, Tom P. ; Emery, Bill ; Maximenko, Nikolai ; Romeiser, Roland ; Graber, Hans C. ; Alvera Azcarate, Aida ; Hughes, Chris W. ; Vandemark, Douglas ; da Silva, Jose ; Van Leeuwen, Peter Jan ; Naveira Garabato, Alberto C. ; Gemmrich, Johannes ; Mahadevan, Amala ; Marquez, Jose ; Munro, Yvonne ; Doody, Sam ; Burbidge, GeoffHigh-resolution satellite images of ocean color and sea surface temperature reveal an abundance of ocean fronts, vortices and filaments at scales below 10 km but measurements of ocean surface dynamics at these scales are rare. There is increasing recognition of the role played by small scale ocean processes in ocean-atmosphere coupling, upper-ocean mixing and ocean vertical transports, with advanced numerical models and in situ observations highlighting fundamental changes in dynamics when scales reach 1 km. Numerous scientific publications highlight the global impact of small oceanic scales on marine ecosystems, operational forecasts and long-term climate projections through strong ageostrophic circulations, large vertical ocean velocities and mixed layer re-stratification. Small-scale processes particularly dominate in coastal, shelf and polar seas where they mediate important exchanges between land, ocean, atmosphere and the cryosphere, e.g., freshwater, pollutants. As numerical models continue to evolve toward finer spatial resolution and increasingly complex coupled atmosphere-wave-ice-ocean systems, modern observing capability lags behind, unable to deliver the high-resolution synoptic measurements of total currents, wind vectors and waves needed to advance understanding, develop better parameterizations and improve model validations, forecasts and projections. SEASTAR is a satellite mission concept that proposes to directly address this critical observational gap with synoptic two-dimensional imaging of total ocean surface current vectors and wind vectors at 1 km resolution and coincident directional wave spectra. Based on major recent advances in squinted along-track Synthetic Aperture Radar interferometry, SEASTAR is an innovative, mature concept with unique demonstrated capabilities, seeking to proceed toward spaceborne implementation within Europe and beyond.