Jeffrey J. Early

Oregon State University, Corvallis, Oregon, United States

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Publications (4)40.55 Total impact

  • Jeffrey J. Early ·
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    ABSTRACT: By starting with a free particle and successively adding constraints, it is shown that the free motion of a particle constrained to the Earth's surface is inertial, despite statements in the literature to the contrary, and that an observer on this particle would not measure a force tangent to the Earth's surface. However, if the observer extended his measurements to include the direction normal to the Earth's surface then he would detect an oscillating force. Copyright © 2012 Royal Meteorological Society
    Quarterly Journal of the Royal Meteorological Society 10/2012; 138(668). DOI:10.1002/qj.1917 · 3.25 Impact Factor
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    ABSTRACT: Oceanic Rossby waves have been widely invoked as a mechanism for large-scale variability of chlorophyll (CHL) observed from satellites. High-resolution satellite altimeter measurements have recently revealed that sea-surface height (SSH) features previously interpreted as linear Rossby waves are nonlinear mesoscale coherent structures (referred to here as eddies). We analyze 10 years of measurements of these SSH fields and concurrent satellite measurements of upper-ocean CHL to show that these eddies exert a strong influence on the CHL field, thus requiring reassessment of the mechanism for the observed covariability of SSH and CHL. On time scales longer than 2 to 3 weeks, the dominant mechanism is shown to be eddy-induced horizontal advection of CHL by the rotational velocities of the eddies.
    Science 09/2011; 334(6054):328-32. DOI:10.1126/science.1208897 · 33.61 Impact Factor
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    Jeffrey J. Early · R. ~M. Samelson · Dudley B. Chelton ·
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    ABSTRACT: The long-term evolution of initially Gaussian eddies is studied in a reduced-gravity shallow-water model using both linear and nonlinear quasigeostrophic theory in an attempt to understand westward-propagating mesoscale eddies observed and tracked by satellite altimetry. By examining both isolated eddies and a large basin seeded with eddies with statistical characteristics consistent with those of observed eddies, it is shown that long-term eddy coherence and the zonal wavenumber-frequency power spectral density are best matched by the nonlinear model. Individual characteristics of the eddies including amplitude decay, horizontal length scale decay, and zonal and meridional propagation speed of a previously unrecognized quasistable state are examined. The results show that the meridional deflections from purely westward flow (poleward for cyclones and equatorward for anticyclones) are consistent with satellite observations. Examination of the fluid transport properties of the eddies shows that an inner core of the eddy, defined by the zero relative vorticity contour, contains only fluid from the eddy origin, whereas a surrounding outer ring contains a mixture of ambient fluid from throughout the eddy's lifetime.
    Journal of Physical Oceanography 08/2011; 41(8). DOI:10.1175/2011JPO4601.1 · 2.86 Impact Factor
  • Jeffrey J. Early · Juha Pohjanpelto · Roger M. Samelson ·
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    ABSTRACT: The method of group foliation can be used to construct solutions to a system of partial differential equations that, as opposed to Lie’s method of symmetry reduction, are not invariant under any symmetry of the equations. The classical approach is based on foliating the space of solutions into orbits of the given symmetry group action, resulting in rewriting the equations as a pair of systems, the so-called automorphic and resolvent systems, involving the differential invariants of the symmetry group, while a more modern approach utilizes a reduction process for an exterior differential system associated with the equations. In each method, solutions to the reduced equations are then used to reconstruct solutions to the original equations. We present an application of the two techniques to the one-dimensional Korteweg-de Vries equation and the two-dimensional Flierl-Petviashvili (FP) equation. An exact analytical solution is found for the radial FP equation, although, it does not appear to be of direct geophysical interest.
    Discrete and Continuous Dynamical Systems 08/2010; 27(4). DOI:10.3934/dcds.2010.27.1571 · 0.83 Impact Factor