Speed Presentation 2024 Australian Marine Sciences Association Annual Meeting combined with NZMSS

Dispersion Characteristics in the East Australian Current System (#649)

Luke A. J. Matisons 1 , Moninya Roughan 1 , Amandine Schaeffer 1
  1. UNSW, Kingsford, NSW, Australia

Dispersion is a fundamental physical mechanism that shapes marine ecosystems through transporting and mixing heat, salt, and nutrients, as well as affecting the distribution and connectivity of organisms. To best apply and model dispersion, an understanding of its underlying advective and turbulent components is required. However, in many circumstances, turbulent dispersion may be parameterized incorrectly, or lack a sufficient empirical consensus. Using data collected as part of NOAA’s surface velocity drifter program, we conduct an in-depth analysis of turbulent dispersion characteristics in the EAC system and elucidate the presence of any spatial heterogeneity or anisotropy in diffusivity parameters. We show turbulent dispersion is roughly isotropic throughout the EAC system but is more meridionally skewed in the northern, jet dominated region, than in the south. Similarly, the magnitude of diffusivity is relatively spatially uniform throughout the EAC system, with maximum diffusivities of ~106 m2/s.  Our findings suggest that spatially variable dispersion in the EAC system is driven predominantly by mean advection, but also highlight the need for better model parameterizations and applications that can account for anisotropic or spatially inhomogeneous turbulent dispersion characteristics. These results will contribute to more accurate modelling, and contribute to our understanding of larval transport and connectivity.