Beschreibung: Oceanographic measurements by groups from the Federal Republic of Germany contributed mainly to the C-Scale Experiment (centered at 9° N, 23° W) and the Equatoria1 Experiment. In this paper the data are presented that were obtained from the moorings F 1 and F 2 in the C-area. After a short discussion of instrument problems, data processing and statistical analysis, the data are presented graphically as time series, progressive vector diagrams, frequency distributions and spectra of horizontal kinetic energy and of temperature variance.

Beschreibung: Some current meter data obtained from a mooring at 2450 m water depth near the continental slope off Portugal are presented. The mean currents at five levels with observations are northward. Mean speeds in the core of the Mediterranean Water exceed speeds at shallower levels by 2 to 3 cm/sec, indicating advection connected to this specific water mass. The current variability is dominated by semi-diurnal tidal components. Normal mode analysis reveals a predominant mode of order 2, representing 48% of the total kinetic tidal energy. Results for the barotropic tidal component are in good agreement with earlier predictions for this area. The motion at higher frequencies ω in the internal gravity wave band can be well described by a ω-2 power law for the energy density spectrum. This result is consistent with earlier observations in other parts of the ocean.

Beschreibung: Auswerte- und Synthesephase Forderzeitraum 01.10.1997-31.03.2000 BMBF-Projekt JGOFS IV/ESTOC FKZ: 03F0202A TP 3

Beschreibung: A complete set of linearly independent relationships among the different cross spectral components obtained from pairs of moored instruments is derived which can be utilized to test whether or not the observed fluctuations within the internal wave frequency band represent a field of propagating internal waves. A further complete set of relationships is derived which enables to test whether or not the internal wave field is horizontally isotropic and (or) vertically symmetric. These relations are compared with corresponding relations for alternative models (standing internal wave modes, three-dimensional isotropic turbulence) and their capability to discriminate between the various models is investigated. The tests are applied to a set of data for which it is found that the observed fluctuations are consistent with both propagating and standing internal waves whereas isotropic turbulence must be rejected for the most part of the internal wave frequency band.

Beschreibung: Zonal transports of North Atlantic Deep Water (NADW) in the South Atlantic are determined. For this purpose the circulation of intermediate and deep water masses is established on the basis of hydrographic sections from the World Ocean Circulation Experiment (WOCE) and some pre-WOCE sections, using temperature, salinity, nutrients, and anthropogenic tracers. Multiple linear regression is applied to infer missing parameters in the bottle dataset. A linear box-inverse model is used for a set of closed boxes given by sections and continental boundaries. After performing a detailed analysis of water mass distribution, 11 layers are prescribed. Neutral density surfaces are selected as layer interfaces, thus improving the description of water mass distribution in the transition between the subtropical and subpolar latitudes. Constraints for the inverse model include integral meridional salt and phosphorus transports, overall salt and silica conservation, and transports from moored current meter observations. Inferred transport numbers for the mean meridional thermohaline overturning are given. Persistent zonal NADW transport bands are found in the western South Atlantic, in particular eastward flow of relatively new NADW between 20° and 25°S and westward flow of older NADW to the north of this latitude range. The axis of the eastward transport band corresponds to the core of property distributions in this region, suggesting Wüstian flow. Part of the eastward flow appears to cross the Mid-Atlantic Ridge at the Rio de Janeiro Fracture Zone. Results are compared qualitatively with deep float observations and results from general circulation models

Beschreibung: Two major water masses dominate the deep layers in the Mariana and Caroline Basins: the Lower Circumpolar Water (LCPW), arriving from the Southern Ocean along the slopes north of the Marshall Islands, and the North Pacific Deep Water (NPDW) reaching the region from the northeastern Pacific Ocean. Hydrographic and moored observations and multibeam echosounding were performed in the East Mariana and the East Caroline Basins to detail watermass distributions and flow paths in the area. The LCPW enters the East Mariana Basin from the east. At about 13°N, however, in the southern part of the basin, a part of this water mass arrives in a southward western boundary flow along the Izu–Ogasawara–Mariana Ridge. Both hydrographic observations and moored current measurements lead to the conclusion that this water not only continues westward to the West Mariana Basin as suggested before, but also provides bottom water to the East Caroline Basin. The critical throughflow regions were identified by multibeam echosounding at the Yap Mariana Junction between the East and West Mariana Basins and at the Caroline Ridge between the East Mariana and East Caroline Basins. The throughflow is steady between the East and West Mariana Basins, whereas more variability is found at the Caroline Ridge. At both locations, throughflow fluctuations are correlated with watermass property variations suggesting layer-thickness changes. The total transport to the two neighboring basins is only about 1 Sverdrup (1Sv ≡ 106 m3 s−1) but has considerable impact on the watermass structure in these basins. Estimates are given for the diapycnal mixing that is required to balance the inflow into the East Caroline Basin. Farther above in the water column, the high-silica tongue of NPDW extends from the east to the far southwestern corner of the East Mariana Basin, with transports being mostly southward across the basin.