Search

Recent observational studies have provided detailed descriptions of double‐diffusive staircases in the Beaufort Sea, characterized by well‐mixed intrusions between high‐gradient interfaces. These structures result from double‐diffusive convection, occurring when cooler fresh water lies atop the warmer saltier Atlantic water layer. In the present study, we investigate the spatial structure of such layers, by analyzing combined high resolution data from a subsurface mooring, a ship‐towed profiling conductivity‐temperature‐depth/ADCP package, and a free‐falling microstructure profiler. At large scale, the modular microstructure profiler data suggest a horizontal “ragged edge” of the layered water masses near the basin boundary. At smaller scales, the mooring data indicate that, in the 300–400 m depth interval, regions of layers abruptly appear. This laterally sharp (of the order of 100 m) interface is advected southwards, as shown by the shallow water integrated mapping system survey conducted nearby. Neither disruption nor formation of layers is directly observed in our data, and we thus interpret our observations as the stable and possibly recent abutment of a layered and an unlayered water masses, now globally advected southwards by a large scale flow.

Double diffusion refers to a variety of turbulent processes in which potential energy is released into kinetic energy, made possible in the ocean by the difference in molecular diffusivities between salinity and temperature. Here, we present a new method for estimating the kinetic energy dissipation rates forced by double-diffusive convection using temperature and salinity data alone. The method estimates the up-gradient diapycnal buoyancy flux associated with double diffusion, which is hypothesised to balance the dissipation rate. To calculate the temperature and salinity gradients on small scales we apply a canonical scaling for compensated thermohaline variance (or ‘spice’) on sub-measurement scales with a fixed buoyancy gradient. Our predicted dissipation rates compare favorably with microstructure measurements collected in the Chukchi Sea. Fine et al. (2018) showed that dissipation rates provide good estimates for heat fluxes in this region. Finally, we show the method maintains predictive skill when applied to a sub-sampling of the CTD data.

Item does not contain fulltext, Adolf Beck, born in 1863 at Cracow (Poland), joined the Department of Physiology of the Jagiellonian University in 1880 to work directly under the supervision of the prominent physiology professor, Napoleon Cybulski. Following his suggestion, Beck started experimental studies on the electrical brain activity of animals, especially in response to sensory stimulation. Beck placed electrodes directly on the surface of brain to localize brain potentials that were evoked by sensory stimuli. He observed spontaneous fluctuations in the electrical brain activity and noted that these oscillations ceased after sensory stimulation. He published these findings concerning the electrical brain activity, such as spontaneous fluctuations, evoked potentials, and desynchronization of brain waves, in 1890 in the German language Centralblatt fur Physiologie. Moreover, an intense polemic arose between physiologists of that era on the question of who should claim being the founder of electroencephalography. Ultimately, Richard Caton from Liverpool showed that he had performed similar experiments in monkeys years earlier. Nevertheless, Beck added new elements to the nature of electrical brain activity. In retrospect, next to Richard Caton, Adolf Beck can be regarded, together with Hans Berger who later introduced the method to humans, as one of the founders of electroencephalography. Soon after his success, Beck got a chair at the Department of Physiology of the University at Lemberg, now Lviv National Medical University.