Validation of simulation against experimental data of deep water moorings in severe sea conditions

Abstract

JAMSTEC (Japan Agency for Marine Earth Science and Technology) deployed a deep water mooring down to 4 500 m which was deployed in 2012 and recovered in 2013 in the Southern Ocean at 60 degree south latitude. CSIRO (Commonwealth Science and Industry Research Organization) has also been operating deep water moorings down to 4 500 m south of Tasmania, Australia at 47 degree south latitude. Both of these moorings are designed to monitor both sub-surface and air-surface flux variability to study global climate change. CSIRO has been designing moorings using a CSIRO developed static analysis based design process. The CSIRO design approach is in strong contrast with that of JAMSTEC. In order to examine the performance and merits of these two approaches, a comparison of these methods is conducted along with data obtained from both moorings both at 47 degree and 60 degree south latitude, where sea conditions are severe. From the results, the maximum tension obtained from the mooring at 47 degree south latitude in the CSIRO analysis program showed variability between 20 to 40% when compared to field data. In the addition the maximum tension obtained from the mooring at 60 degree south latitude showed higher analysis variability from 50 to 100% variability. These results show that although both the JAMSTEC and CSIRO analysis methods can calculate appropriate tension trends and distributions for moorings at high latitudes, some adjustment in amplitudes may be warranted, as well as a potential adjustment to the factors of safety in use during mooring design. This paper presents the details of this analysis and makes recommendations on simulation methodology to improve results.