A tale of two spicy seas

MacKinnon, JA, Nash JD, Alford MH, Lucas AJ, Mickett JB, Shroyer EL, Waterhouse AF, Tandon A, Sengupta D, Mahadevan A, Ravichandran M, Pinkel R, Rudnick DL, Whalen CB, Alberty MS, Lekha JS, Fine EC, Chaudhuri D, Wagner GL.  2016.  A tale of two spicy seas. Oceanography. 29:50-61.

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horizontal density structure, impact, indian-ocean, mixed-layer instabilities, parameterization, restratification, spectra, surface-layer, turbulence, upper-ocean


Upper-ocean turbulent heat fluxes in the Bay of Bengal and the Arctic Ocean drive regional monsoons and sea ice melt, respectively, important issues of societal interest. In both cases, accurate prediction of these heat transports depends on proper representation of the small-scale structure of vertical stratification, which in turn is created by a host of complex submesoscale processes. Though half a world apart and having dramatically different temperatures, there are surprising similarities between the two: both have (1) very fresh surface layers that are largely decoupled from the ocean below by a sharp halocline barrier, (2) evidence of interleaving lateral and vertical gradients that set upper-ocean stratification, and (3) vertical turbulent heat fluxes within the upper ocean that respond sensitively to these structures. However, there are clear differences in each ocean's horizontal scales of variability, suggesting that despite similar background states, the sharpening and evolution of mesoscale gradients at convergence zones plays out quite differently. Here, we conduct a qualitative and statistical comparison of these two seas, with the goal of bringing to light fundamental underlying dynamics that will hopefully improve the accuracy of forecast models in both parts of the world.