Nearshore Flow Patterns in a Complex, Tidally Driven System in Summer: Part I. Model Validation and Circulation

Circulation models are often validated with respect to temporal rather than spatial variability, yet spatial variability is often very important for many questions subsequently addressed with the models. We validated a high-resolution nearshore circulation model using both temporal and spatial data sets and used the model to investigate small-scale nearshore flow patterns along the complex eastern Maine coast. The Finite Volume Coastal Ocean Model (FVCOM) was run from April to September 2014. In the temporal comparison, the model captured variation in sea level (model skill of 0.98) and the seasonal warming trend (model skill of 0.94). Temperature fluctuations were largely due to horizontal temperature divergence, implying the sensitivity to the forcing at the open boundary. To evaluate spatial variation in performance, we calculated model skill for current profile transects, which ranged from 0.99 to 0.60 in the east/west direction and 0.99 to 0.62 in the north/south direction. The combination of temporal and spatial validation improved confidence in the model's ability to recreate realistic flow patterns. Residual currents across the entrance to the bays showed flows that move out of the bays via the upper western side and into the bays in the lower water column before surfacing on the eastern side. As the coastal current passed by headlands and islands, eddies formed in the wake of several of them. Residual flows varied among months and location along the shelf. This model is a valuable first step in understanding how particulates move through such a complex and variable nearshore region.