Observations of Double Diffusion in the Upper Ocean
[26-Feb-2014] Walesby, K.T., Vialard, J., and Ward, B.
Presented at the 2014 Ocean Sciences Meeting
The structure of the upper ocean is influenced by a variety of turbulent mixing processes. One of these is double diffusion. This may occur in a fluid whose density is controlled by two variables. Importantly, these variables must also possess different diffusion rates. Seawater is one such fluid capable of displaying this phenomenon, and recent observations have shown that significant portions of the planet's oceans and seas may experience double-diffusive instabilities. Although our understanding of double-diffusive instabilities has improved in recent years, uncertainties remain. There are also relatively few field observations available that display double-diffusion, with most of these so far being made in the tropical North Atlantic region. The Air-Sea Interaction Profiler (ASIP) is a novel, upwardly-rising instrument which has previously been used to measure microstructure within the upper ocean. Here we present results acquired using ASIP from a research cruise in the tropical Indian Ocean. Particular attention is given in our analysis to evaluating evidence for the presence of double-diffusive instabilities.