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Time-resolving optimum multi-parameter (TROMP) analysis is used to study interannual variability of water mass properties in the Southern Ocean in a section between Antarctica and Tasmania for the period 1991-1996. Water mass properties were stable during 1994-1996 but showed departures from their 1994-1996 values during 1991 and 1993. TROMP analysis is unable to quantify the interannual variation in detail, but it is shown that interannual variability does not invalidate the findings of a previous study that was based on the assumption of time-invariable water mass properties and suggested large interannual fluctuations in the water mass volumes south of Tasmania. [ABSTRACT FROM AUTHOR]

A new water mass analysis technique is used to analyse the BATS oceanographic data set in the Sargasso Sea of 1988-1998 for changes in Labrador Sea Water (LSW) properties. The technique is based on a sequential quadratic programming method and requires careful definition of constraints to produce reliable results. Variations in LSW temperature and salinity observed in the Labrador Sea are used to define the constraints. It is shown that to minimize the residuals while matching the observed temperature and salinity changes in the source region the nitrate concentration in the Labrador Sea has to be allowed to vary as well. It is concluded that during the period of investigation nitrate underwent significant variations in the Labrador Sea. [ABSTRACT FROM AUTHOR]

A water mass analysis method based on a constrained minimization technique is developed to derive water property changes in water mass formation regions from oceanographic station data taken at significant distance from the formation regions. The method is tested with two synthetic data sets, designed to mirror conditions in the North Atlantic at the Bermuda BATS time series station. The method requires careful definition of constraints before it produces reliable results. It is shown that an analysis of the error fields under different constraint assumptions can identify which properties vary most over the period of the observations. The method reproduces the synthetic data sets extremely well if all properties other than those that are identified as undergoing significant variations are held constant during the minimization. [ABSTRACT FROM AUTHOR]

A new water mass analysis technique is used to analyse the BATS oceanographic data set in the Sargasso Sea of 1988-1998 for changes in Labrador Sea Water (LSW) properties. The technique is based on a sequential quadratic programming method and requires careful definition of constraints to produce reliable results. Variations in LSW temperature and salinity observed in the Labrador Sea are used to define the constraints. It is shown that to minimize the residuals while matching the observed temperature and salinity changes in the source region the nitrate concentration in the Labrador Sea has to be allowed to vary as well. It is concluded that during the period of investigation nitrate underwent significant variations in the Labrador Sea. [ABSTRACT FROM AUTHOR]

A detailed high resolution survey of a small region (68 × 68 km) of the Subtropical Front south of Australia over a period of 14 days is used to study the interaction between the mixed layer and the permanent frontal structure underneath during summer conditions. The front extends through the mixed layer as a salinity front, while its temperature structure is modified by seasonal warming. Wind-driven movement of the mixed layer combines with the short-time development of indentations and filaments in the front to produce some degree of decoupling between the mixed layer and the underlying structure, and the front is not always found at the same location in and below the mixed layer. Intrusions and parcels of distinct water properties are found just below the mixed layer, produced as a result of the relative movement of the front in and below the mixed layer. These parcels are typically 10 km in width and 10-50 m in depth. Successive surveys of the front with a time separation of 2 days showed that these features persist over at least 1 week. Large scale surveys of the front show that parcels are ubiquitous along the Subtropical Front over a distance of several hundred kilometres. The results suggest that any study aimed at understanding the intricate interaction between the mixed layer and the layers below in oceanic fronts will have to address wind-driven dynamics and frontal dynamics together. [ABSTRACT FROM AUTHOR]

Presents a study on a barrier layer found in the southern region of the South China Sea based on CTD data gathered during six cruises between 1989 and 1999. Data and methods; Results; Characteristics of the barrier layer.