Journal of Geophysical Research: Oceans
© American Geophysical Union
Impact Factor: 3.318
ISI Journal Citation Reports © Ranking: 2015: 27/184 (Geosciences Multidisciplinary)
Online ISSN: 2169-9291
Associated Title(s): Journal of Geophysical Research
New method presented for calculating horizontal eddy diffusion
Turbulent features in the ocean, such as fronts, eddies, and filaments, occur when waters of different properties—such as temperature, salinity, density, or velocity—collide. Their dynamics are difficult to study because of their relatively small size (1–10 kilometers) and ephemeral lifetime (on the order of few days). Nonetheless, they have a large influence on how particles, heat, and salt are mixed and transferred in the ocean.
The rate at which materials or energy are being mixed in these structures is estimated by the so-called horizontal eddy diffusivity, a key coefficient for ocean circulation studies and climate models. Recent advances in technology have improved the understanding of these features through high-resolution numerical models, but investigating their dynamics at sea still presents a challenge.
Nencioli et al. present a new method for calculating horizontal eddy diffusivity through direct observations at sea by combining data from thermosalinographs, instruments mounted on research ships to measure ocean surface temperature, with data from Lagrangian buoys, instruments floating in the water and transmitting their positions via satellite.
The authors note that this new method provides a less expensive and more efficient way of calculating the values of this complex coefficient. Armed with this, scientists can better reconstruct how processes at the ocean surface transfer energy and material across the globe and they can improve ocean and climate modeling.