Shear Mircrostructure


PI:L. Padman

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Our guides to conditions that might be seen in developing NES instabilities are data from an icemoored array of thermistors that we deployed during ANZFLUX (Fig. PA1) and output from the Harcourt LES model (Fig. PA2). The qualitative agreement between the maps of T(t,z) from ANZFLUX and modeling lends credence to model predictions, although the difference in development time scales suggests that we cannot yet adequately reproduce the effects of these instabilities. Based on several factors, we hypothesized that the ANZFLUX IML (Fig. PA1) developed as the SML density rose rapidly due to lateral advection of more saline (thus, denser) SML fluid from the top of Maud Rise. We also suspect that double-diffusive convection (“DDC”) may be responsible for the existence of a thin IML (yellow area for t<218.3 in Fig. 1). The measurement program outlined below is designed to capture the small- and microscale structure of the SML, shear-driven and DDC mixing in the pycnocline prior to the development of thick IMLs, and the evolution of rapidly expanding IMLs.