Simulating Argo profiling float trajectories and along-track biogeochemical variability in the California Current System using a high-resolution global model

A large ensemble (~10,000) of Argo profiling float trajectories are simulated and variability in key physical and biogeochemical properties along their tracks is studied using a 1/8° global ocean biogeochemical model (NOAA GFDL’s MOM6-COBALT) in the California Current System (25-50°N, 114-132°W). We demonstrate that our high-resolution model is capable of resolving meso- and submesoscale physical dynamics (e.g. eddies, frontal filaments) and their biogeochemical impacts in this region. We use model simulated daily velocity fields to represent the vertical and horizontal motions of the virtual floats, which are released at 822 locations in the summertime of different years. A Lagrangian particle tracking framework is then used to project float trajectories over a future 5-year period. We show that probability density functions and spatial spans of projected float displacements are largely dependent on their initial release locations and display a distinct meridional pattern. Analyses of simulated along-track physical and biogeochemical fields suggest that spatio-temporal variability in float observables can be adequately sampled with a typical 10-day profiling interval. Furthermore, simulated float displacements and along-track variability are compared against a suite of real float trajectories and measurements to explore the uncertainties in our projections. This study aims to use numerical approaches to provide new insights into float deployment planning, sampling strategies, and data interpretation.