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Notes, comments and questions on Thomas et al. (2007) and other papers

Comments

  • The strain can localize submesoscale features but it can do it even from the mesoscale motion alone. I don’t think so. On the other hand, is it indeed the power of finite-size Lyapunov exponents (FSLE) to be able to predict the presence of submesoscale processes from the mesocale flow alone. Any paper on that?
  • The upwelling region extends up to 5-15 km from the position of the front. The downwelling region is smaller but more intense.
  • (from Calil and Richards 2009) The upwelling is on the warm side of the front, the downwelling on the cold side.
  • (from Legal et al. 2007) Vertical velocity is positive in lighter filaments and negative in denser filaments; as such, there is a quasi-linear anit-correlation between vertical velocity and density anomaly (their Fig. 6 with p. 1420 and Figs. 8 and 9 with p. 1421). We thus expect upwelling due to frontogenesis in region where the isopycnals are deeper than normal –in other words in region that could be considered a downwelling area. This is weird. Is the process (the original front) reponsible for the anomalous depths of the isopycnals not as important in triggering upwelling and downwelling region?

References to read

  • High-resolution 3D numerical experiments with downscaling:
    • Boccaletti, G., R. Ferrari, and B. Fox-Kemper (2007), Mixed layer instabilities and restratification, J. Phys. Oceanogr., in press.
    • Capet, X., J. McWilliams, M. Molemaker, and A. Shchepetkin (2007a), Mesoscale to submesoscale transition in the California Current system: Flow structure, eddy flux, and observational tests, J. Phys. Oceanogr., p. submitted.
  • Observations:
    • Flament, P., L. Armi, and L. Washburn (1985), The evolving structure of an upwelling filament, J. Geophys. Res., 90, 11,765–11,778.
  • Numerical simulations focusing on the vertical advection and impact on nutrient distribution:
    • Mahadevan, A., and D. Archer (2000), Modeling the impact of fronts and mesoscale circulation on the nutrient supply and biogeochemistry of the upper ocean, J. Geophys. Res., 105(C1), 1209–1225.
    • Mahadevan, A., and J. Campbell (2002), Biogeochemical patchiness at the sea surface, Geophys. Res. Lett., 29(19), 1926, doi:10.10292001GL014,116.
    • Mahadevan, A., and A. Tandon (2006), An analysis of mechanisms for submesoscale vertical motion at ocean fronts, Ocean Modelling, 14 (3-4), 241–256.
    • Oschlies, A. (2002), Can eddies make ocean deserts bloom?, Global Biogeochemical Cycles, 16, 1106, doi:10.1029/2001GB001,830.
    • Martin, A., and P. Pondaven (2003), On estimates for the vertical nitrate flux due to eddy-pumping, J. Geophys. Res., 108(C11), 3359, doi: 10.1029/2003JC001,841.