IMPACT OF FINE-SCALE PHYSICS ON MARINE ECOSYSTEM AND CARBON DYNAMICS IN THE NORTH PACIFIC SUBTROPICAL GYRE: PERSPECTIVES FROM A NEW MODELING APPROACH (E)
In the subtropical gyres there exists spatial and temporal patchiness across a wide range of scales. As ocean surface temperatures continue to rise, global climate models suggest that the strength of these gyres as biological carbon pumps may diminish due to increased stratification and depleted nutrients over large scales. However, such predictions often ignore climate-physical-ecosystem interactions on much finer scales due to computational constraints and lack of observational evidence. In order to assess ecosystem responses to fine-scale physics, we introduced a new and computationally tractable modeling approach, the Spatially Heterogeneous Dynamic Plankton (SHiP) model, which allows for subgrid-scale heterogeneity in resource environments through the probabilistic representation of fine-scale perturbations. We applied the SHiP model to the Hawaiian Ocean Time-series (HOT) site in the North Pacific Subtropical Gyre, and compared the model output to high-resolution observations from satellites, automatous platforms, and field campaigns (i.e. HOE-DYLAN). The model yielded substantially different phytoplankton community compositions and carbon dynamics when running in a temporally and spatially heterogeneous mode relative to the traditional homogeneous approach. The model also successfully captured the full range of variability observed at the HOT site. Our findings suggest that both the temporal scale (e.g. duration) and intensity of perturbations are extremely relevant to the responsiveness of ecosystem and carbon dynamics. This indicates that future changes in fine-scale physical dynamics may have significant impact on marine ecosystem structures and carbon cycling.
Liu, X., University of Southern California, USA, email@example.com
Levine, N. M., University of Southern California, USA
Presentation is given by student: Yes