A comparative study of spatial resolution in ocean circulation models and its impact in Lagrangian particle tracking simulations

Lagrangian particle tracking models are used to explore how physical processes influence the transport of particles (e.g. eggs, larvae or propagules) in the ocean. On the Oregon continental shelf and slope, the Northern California Current system, interacts with spatially and temporally variable coastal currents driven by weather, tides, and topography. Particle tracking simulations conducted with a 2km resolution model, indicate that typical residence times on the Oregon shelf are less than three weeks. But retention, particularly nearshore, may be dependent on accurate representation of smaller scale physical processes than are typically resolved in coastal ocean circulation models. To examine this, our study compares and contrasts results of particle tracking simulations based on flow fields from two ocean circulation models with different spatial resolutions (2km, 250m) over a domain that encompasses the Oregon coastal environment (40.7°N to 47.0°N, -123.2°W to -126°W). We employed our Lagrangian particle tracking model to examine how model resolution affects transport and retention characteristics on the Oregon shelf. Specifically, we examined particle import (e.g. total number of incoming particles from all origin locations), local retention (e.g. proportion of locally produced particles that are locally retained), and self-recruitment (e.g. ratio of locally produced larvae retained in each area to total number of incoming larvae). Finally, we used our model to analyze the oceanographic connectivity in this ecologically and commercially important Oregon Marine Reserves System.