Albion Lawrence

Submesoscale flows have been seen in simulations and shipboard data to exhibit qualitative seasonal changes, consistent with submesoscale baroclinic instabilities being activated in deep winter mixed layers. To further test and understand this, we use Jason-2/OSTM satellite data to compute along-track sea surface height (SSH) spectra across the global ocean, for each calendar month. The balanced flow is modeled by a low-wavenumber plateau transitioning to a submesoscale power-law falloff. When tides are weak, we find statistically significant variation with location and season in the parameters describing balanced motion. Our model of the signal and altimeter noise produces a power-law falloff which is closer to the results of numerical models and in situ measurements as compared to prior altimetry-based studies. The power law exponent decreases in the winter and increases in the summer, and there is evidence of kinetic energy moving upwards to larger scales in the months following the month of maximum mixed layer depth. This correlates with the deepening and shoaling of the mixed layer (computed from climatology) and is consistent with shipboard ADCP data.

We study the open system dynamics of a harmonic oscillator "system" coupled to an "environment" of oscillators with an exponential density of states, motivated by holographic models of non-gravitational "little" string theories. We present the Heisenberg equations of motion and the quantum master equation for the system, and develop a renormalization procedure to manage the divergences, which are exponential in the cutoff. We provide evidence that the renormalized system dynamics is Markovian even when the initial state of the environment is the instantaneous ground state.