Evaluating global ocean reanalysis systems for the greater Agulhas Current System

• Main Author: Cooper, Kyle Francis
• Other Authors: Backeberg, Bjorn Christoph
• Format: Dissertation
• Language: English
• Published: University of Cape Town 2015
• Subjects: Oceanography
• Online Access: http://hdl.handle.net/11427/12829

Includes bibliographical references. === Operational oceanography aims to accurately hindcast and forecast the state of the ocean. An international initiative, the Global Ocean Data Assimilation Experiment (GODAE), developed and increased the capacity for global operational oceanography. However, the products from the global initiatives were regionally inapplicable due to low spatial resolutions, and have recently improved through GODAE OceanView. A number of local operational oceanographic initiatives have been setup over the southern African regional ocean, but proved to be unsustainable and ended. Recently, the aim to develop a regional ocean prediction system has arisen, and initial steps have been taken. This thesis aims to address the lack of local capacity in operational oceanography, and contribute to a crucial process in developing a regional ocean prediction system. Here, we validate and investigate the differences between three global reanalysis products, namely MyOcean (GLORYS2V1), HYCOM (U.S Naval Research Laboratory) and BlueLINK (OFAM3). These reanalysis products are validated and investigated over the greater Agulhas Current System, which is a crucial system in Southern African regional ocean. The salient oceanographic features represented in the reanalysis products are initially compared to historical literature of the region and followed by available unassimilated observations (i.e. independent). The results show that the reanalysis products from MyOcean, and the U.S Naval Research Laboratory satisfactorily simulate the major salient oceanographic features of the Agulhas Current System. Bluelink does not correctly portray the structure of the source and retroflection regions, and therefore has limited use over the Agulhas Current System. The differences between the three products indicates that the data assimilate does not sufficiently constrain the models in order for their solutions over the Agulhas System to converge. The evaluation of these global ocean reanalysis products is a critical step toward a regional ocean prediction system over Southern Africa, and building toward the local capacity to accomplish this goal.