We are all familiar with the irregular profiles from modern, high resolution conductivity-temperature-depth profilers (commonly called CTDs) freely falling vertical profilers, and towed thermistor chains (Figs. 1 and 2). In fact sufficient resolution was available back in the 1930s with the advent of the Bathythermograph (BT) (Eckart, 1948) and even earlier through the use of the thermocouple (Schmidt, 1914; and Hacker, 1933). Figures 3 and 4 show thin layers of biological material. Fish and copepods which swim can easily form layers, but what about some of the particles which are very small, neutrally buoyant, and only swim slowly, if at all. Are their profiles related to the temperature, density, or their gradients? The easily measured profiles of temperature, salinity, density etc., carry a signature of the relevant physical processes. How much do they tell us about the formation of the biological and chemical layers?

Osborn, T. 1998. Finestructure, microstructure, and thin layers. Oceanography 11(1):36–43, https://doi.org/10.5670/oceanog.1998.13.

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