An optimum multiparameter mixing analysis of the shelf waters inthe Ross Sea

[摘要] The analysis of the mixing processes involving water masses on the Ross Sea continental shelf isone of the goals of the CLIMA project (Climatic Long-term Interactions for the Mass balance in Antarctica).This paper uses extended Optimum MultiParameter analysis (OMP), which is applied to four datasetscollected during the cruises of 1994/95, 1995/96, 1997/98 and 2000/01 in the Ross Sea (Antarctica). Datainclude both hydrological, (temperature, salinity, and pressure; T, S, and P, respectively) and chemicalparameters (O2, Si(OH)4, PO4, and NO3+NO2). The OMP analysis is based on the assumption that the mixingis a linear process which affects all parameters equally so that each sample shows physical/chemicalproperties that are the result of the mixing of some properly selected Source Water Types (SWTs). OMP thusevaluates the best set of contributions by all SWTs to each sample, and allows the spatial distribution andstructure of the water masses in a basin to be evaluated. Ocean circulation may subsequently be inferred bymeans of a deeper analysis of the spreading of the water mass. In this study, the “real” Redfield ratiosobserved in the Ross Sea were used to correct the equations referring to the chemical parameters inaccordance with the extended version of OMP. The solutions include some physically realistic constraints.The results allow a detailed description of the water mass distribution, validated through comparison withsome “canonical” thermohaline characteristics of the Ross Sea hydrology. In particular our results verify thespreading of the HSSW over the entire continental shelf and emphasize the key role it plays in the ventilationof the deep waters outside the Ross Sea. In addition a description is given of the intrusion of relatively warmwaters coming from the open ocean and flowing at some specific locations at the continental shelf break.

[学科分类] 自然科学（综合）