261d0e04-059c-45b2-949f-2e22f1b0e469 urn:uuid eng UTF-8 nonGeographicDataset nonGeographicDataset 2025-11-17T03:28:03 creation ISO 19115 2016 Subantarctic zone oceanography - SAZ Project 1997-1998 - Phosphate Modeling 261d0e04-059c-45b2-949f-2e22f1b0e469 Oceanographic processes in the subantarctic region contribute crucially to the physical and biogeochemical aspects of the global climate system. To explore and quantify these contributions, the Antarctic Cooperative Research Centre (CRC) organised the SAZ Project, a multidisciplinary, multiship investigation carried out south of Australia in the austral summer of 1997-1998. Taken from the abstracts of the referenced paper: We developed and applied a one-dimensional (z) biophysical model to the Subantarctic Zone (SAZ) and the Polar Frontal Zone (PFZ) to simulate seasonal phosphate export production and resupply. The physical component of our model was capable of reproducing the observed seasonal amplitude of sea surface temperature and mixed layer depth. In the biological component of the model we used incident light, mixed layer depth, phosphate availability, and estimates of phytoplankton biomass from the Sea-viewing Wide Field-of-view Sensor to determine production and tuned the model to reproduce the observed seasonal cycle of phosphate. We carried out a series of sensitivity studies, taking into account uncertainties in both physical fields and biological formulations (including potential influence of iron limitation), which led to several robust conclusions (as represented by the ranges below). The major growing season contributed 66-76% of the annual export production in both regions. The simulated annual export production was significantly higher in the PZF (68-83 mmol P m-2) than in the SAZ (52-61 mmol P m-2) despite the PFZ's having lower seasonal nutrient depletion. The higher export production in the PFZ was due to its greater resupply of phosphate to the upper ocean during the September to March period (27-37 mmol P m-2) relative to that in the SAZ (8-15 mmol P m-2). Hence seasonal nutrient depletion was a better estimate of seasonal export production in the SAZ, as demonstrated by its higher ratio of seasonal depletion/export (64-78%) relative to that in the PFZ (34-47%). In the SAZ, vertical mixing was the dominant mechanism for supplying phosphate to the euphotic zone, whereas in the PFZ, vertical mixing supplied only 37% of the phosphate to the euphotic zone, whereas in the PFZ, vertical mixing supplied only 37% of the phosphate to the euphotic zone and horizontal transport supplied the remaining 63%. {"type": "Point", "coordinates": [141.5, -55.0]} 141.5 141.5 -55.0 -55.0 ACE/CRC AMD AMD/AU CEOS EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > NUTRIENTS EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > PHOSPHATE GEOGRAPHIC REGION > POLAR OCEAN > SOUTHERN OCEAN Phosphate R/V AA > R/V Aurora Australis SAZ SHIPS PROJECT HOME PAGE documentDigital Public information for ASAC project 2256 HTML VIEW RELATED INFORMATION documentDigital Download point for the referenced publication - AAD Staff only HTML VIEW RELATED INFORMATION documentDigital Citation reference for this metadata record and dataset HTML Creative Commons by Attribution logo documentDigital PNG