3-D Ocean Particle Tracking Modeling Reveals Extensive Vertical Movement and Downstream Interdependence of Closed Areas in the Northwest Atlantic
Novel 3-D passive particle tracking experiments were performed using the Lagrangian particle simulator ‘Parcels’ v 2.1 available at http://www.oceanparcels.org in the northwest Atlantic to elucidate connectivity among areas closed to protect vulnerable marine ecosystems (Wang et al., 2020). Climatological monthly–mean currents were obtained from the Bedford Institute of Oceanography North Atlantic Model (BNAM) ocean model over the period 1990-2015 (Wang et al. 2019). BNAM is an eddy resolving North Atlantic Ocean model with a nominal resolution of 1/12° (approximately ~8 km at the Equator). It is based on NEMO 2.3 (Nucleus for European Modelling of the Ocean) and has a maximum of 50 levels in the vertical, with level thickness increasing from 1 m at the surface to 200 m at a depth of 1,250 m and reaching the maximum thickness of 460 m at the bottom of the deep basins (approximately 5,730 m). BNAM uses partial cell for the bottom layer, which improves the representation of the bottom layer. We provide the monthly-mean U (zonal) V (meridional) and W (vertical) velocities for all 12 months and yearly-averaged current over these months from BNAM in nc format. Also, one mask nc file is given in this area, which includes grid coordinates and indicates the sea (value=1) and land (value=0) of the fields. Using Parcels and BNAM data we examined 1) the degree of vertical movement of particles released at different depths and locations; 2) the location of potential source populations for the deep-sea taxa protected by the closures; and 3) the degree of functional connectivity. We found enhanced connectivity over previously developed 2-D models and unexpected, current-driven, strong (to a maximum of about 1340 m) downward displacement at depth (particles released at 450, 1000 and 2250 m), with weaker upward displacement except for the release depth of 2250 m which showed upward movement of 955 m with a drift duration of 3 months. We provide the distributions of horizontal velocity vectors (cm/s) and vertical velocity contours (m/s x 10-4) at a) 100 m and b) 1,000 m depth in the Flemish Cap area of the northwest Atlantic. These data can be interpolated to reconstruct Figure 8 in our publication and could potentially be used to evaluate benthic pelagic coupling in the region, and be used in species distribution models. Wang, Z., Brickman, D., & Greenan, B.J.W. Characteristic evolution of the Atlantic Meridional Overturning Circulation from 1990 to 2015: An eddy-resolving ocean model study. Deep Sea Res. I. 149, 103056 (2019). https://doi.org/10.1016/j.dsr.2019.06.002.