WAMSI Node 1.1.2 - Coupled hydrodynamic and biogeochemical models

The dynamics of the seasonal evolution of chlorophyll a at the continental shelf break around 32 degrees south has been investigated using a one-dimensional numerical BGC model at shelf and lagoon scales. The results show that a combination of vertical mixing associated with the Leeuwin Current and surface cooling during the winter months is responsible for the wintertime increase in chlorophyll a concentration at the shelf break (Greenwood and Soetaert, 2008). In addition, variation in the timing and magnitude of the winter increase in chlorophyll is shown, for the first time, to relate to the strength of the Leeuwin Current. A nitrogen budget for the southwest WA shelf has been derived by diagnosing the simulated fluxes of particulate and dissolved nitrogen from the 3-D model across the shelf boundaries (across two cross-shelf transects at 27S and 34.5S and across the 100 m isobath) as well as deposition and release of nitrogen at the seafloor.