Hydrology of the Indian Ocean. III. Water masses of the upper 500 metres of the South-east Indian Ocean

The following seven water masses have been identified, and their distribution traced during several seasons of the year: Red Sea mass, with the same distribution and properties in 1962 as the north-west Indian Intermediate described in 1959-60; Persian Gulf mass, which is confined to the region south of Indonesia and is limited in extent of easterly flow by the opposing flow of Banda Intermediate water; upper salinity minimum mass, entering via Lombok Strait and moving zonally in the direction of the prevailing surface currents, a secondary movement of this water mass towards north-west Australia is limited by the northern boundary of a south-east Indian high salinity water mass. This latter water mass occurs as three separate core layers north of 22-23� S. The deep core layer mixes with waters of the oxygen maximum below it, the mid-depth core layer mixes with Persian Gulf and upper salinity minimum water masses, and the upper core layer mixes with the Arabian Sea water mass. The latter water mass spreads eastwards to about 120� E. and southwards to north-west Australia, in conformity with surface currents. A sixth water mass enters with the counter-current and is found as a salinity maximum within the thermocline to about 20� S. A seventh water mass characterized by a salinity maximum around temperatures of 28-29�C has a limited distribution and an unknown origin. Both of these water masses move in the direction of surface currents.

Download Full-text

The continuity of water masses along the western boundary of the Tasman and Coral Seas

Marine and Freshwater Research ◽

10.1071/mf9680077 ◽

1968 ◽

Vol 19 (2) ◽

pp. 77 ◽

Cited By ~ 13

Author(s):

DJ Rochford

Keyword(s):

Water Mass ◽

New Caledonia ◽

Core Layer ◽

Water Masses ◽

Western Boundary ◽

Intermediate Water ◽

North West ◽

The North ◽

Coral Sea ◽

Intermediate Water Mass

Hydrological data of the Umitaka Maru (December 1967) and of H.M.A.S. Gascoyne (November-December 1965) have been used to show continuity of selected water masses from the north-west Coral Sea to the continental margin off New South Wales. The core layer properties of these water masses (salinity, temperature, oxygen) indicate that these water masses of the north-west Coral Sea are formed by the inflow from the east of the South Equatorial water mass (0 m), the upper salinity maximum water mass (150-200 m) of the central South Pacific, and of the Antarctic Intermediate water mass (800-1000 m). The inflow of the first two occurs immediately south of the Solomon Is. whilst that of the third occurs between New Caledonia and the New Hebrides. Continuity of the upper oxygen maximum of the 200-800 m layer was not examined because of doubts as to its existence as a separate water mass.

Download Full-text

WATER MASSES CHARACTERISTICS AT THE SANGHIE TALAUD ENTRY PASSAGE OF INDONESIAN THROUGHFLOW USING INDEX SATAL DATA 2010

Jurnal Ilmu dan Teknologi Kelautan Tropis ◽

10.28930/jitkt.v6i2.9027 ◽

2015 ◽

Vol 6 (2) ◽

Author(s):

Ivonne M Radjawane ◽

Paundra P Hadipoetranto

Keyword(s):

North Pacific ◽

Water Mass ◽

Sea Water ◽

Core Layer ◽

South Pacific ◽

New Guinea ◽

Water Masses ◽

Coastal Current ◽

Indonesian Throughflow ◽

Pacific Water

ABSTRACT Measurement of ocean physical parameters using the CTD was conducted by deep water expedition INDEX-SATAL 2010 (Indonesian Expedition Sangihe-Talaud) in July-August 2010. The aim of this study was to determine the characteristics of water masses around the Sangihe Talaud Water where there was an entry passage of Indonesian throughflow (ITF) at the west pathway that passed through the primary pathway i.e., the Sulawesi Sea and Makassar Strait and the secondary pathway (east pathway) that passed through the Halmahera Sea. The analyses were performed by the method of the core layer and was processed with software Ocean Data View (ODV). The results showed that in the Sangihe Talaud waters there was a meeting water masses from the North Pacific and the South Pacific. The water mass characteristics in main pathway through the Sulawesi Sea was dominated by surface and intermediate North Pacific water masses and carried by the Mindanao Currents. While the Halmahera Sea water mass was dominated by surface and intermediate South Pacific water masses carried by the New Guinea Coastal Current that moved along the Papua New Guinea and Papua coast enters to the Halmahera Sea. Keywords: Index-Satal 2010, Northern Pacific Water Masses, Southern Pacific Water Masses, Sangihe Talaud

Download Full-text

Seasonal variations in the Indian Ocean along 110°E. I. Hydrological structure of the upper 500 m

Marine and Freshwater Research ◽

10.1071/mf9690001 ◽

1969 ◽

Vol 20 (1) ◽

pp. 1 ◽

Cited By ~ 62

Author(s):

DJ Rochford

Keyword(s):

Indian Ocean ◽

Surface Waters ◽

Water Masses ◽

Surface Currents ◽

Temperature Changes ◽

East Indian ◽

Hydrological Structure ◽

The Indian Ocean ◽

The Tropics ◽

East Indian Ocean

Tropical and subtropical water masses at surface and subsurface depths were separated by their salinity, temperature, oxygen, and nutrient characteristics. The annual mean depths and latitudinal extent of these water masses were determined. Annual changes in the upper 50 m were generally so small relative to those found in other oceans that advection and mixing must have been less important in their genesis than local climatic changes. There was a barely significant seasonal rhythm in surface phosphate and nitrate, with peak occurrences of each some 6 months apart. At each latitude the permanent thermal discontinuity centred around a particular isotherm varied little in intensity during the year, but rose and fell in accordance with surface currents. The thermocline south of c. 18�S. varied little in depth but greatly in intensity during the summer. The depth of the mixed layer was much less in summer and at all times shallower in the tropics. The depth of this layer was governed more by the accumulation of surface waters by zonal currents and eddies, than by wind stress or convective overturn. Therefore there was little difference from south to north, or month to month, in average nutrient values of this mixed column. The movement of the various surface waters, deduced from salinity and temperature changes during the year, usually agrees with geostrophic currents across 110�E, and ships' observations of surface currents in the south-east Indian Ocean.

Download Full-text

Water masses in the Atlantic Ocean: characteristics and distributions

Ocean Science ◽

10.5194/os-17-463-2021 ◽

2021 ◽

Vol 17 (2) ◽

pp. 463-486

Author(s):

Mian Liu ◽

Toste Tanhua

Keyword(s):

Atlantic Ocean ◽

Deep Water ◽

Bottom Water ◽

Water Mass ◽

Sea Water ◽

Weddell Sea ◽

Water Masses ◽

Global Ocean ◽

Intermediate Water ◽

The North

Abstract. A large number of water masses are presented in the Atlantic Ocean, and knowledge of their distributions and properties is important for understanding and monitoring of a range of oceanographic phenomena. The characteristics and distributions of water masses in biogeochemical space are useful for, in particular, chemical and biological oceanography to understand the origin and mixing history of water samples. Here, we define the characteristics of the major water masses in the Atlantic Ocean as source water types (SWTs) from their formation areas, and map out their distributions. The SWTs are described by six properties taken from the biased-adjusted Global Ocean Data Analysis Project version 2 (GLODAPv2) data product, including both conservative (conservative temperature and absolute salinity) and non-conservative (oxygen, silicate, phosphate and nitrate) properties. The distributions of these water masses are investigated with the use of the optimum multi-parameter (OMP) method and mapped out. The Atlantic Ocean is divided into four vertical layers by distinct neutral densities and four zonal layers to guide the identification and characterization. The water masses in the upper layer originate from wintertime subduction and are defined as central waters. Below the upper layer, the intermediate layer consists of three main water masses: Antarctic Intermediate Water (AAIW), Subarctic Intermediate Water (SAIW) and Mediterranean Water (MW). The North Atlantic Deep Water (NADW, divided into its upper and lower components) is the dominating water mass in the deep and overflow layer. The origin of both the upper and lower NADW is the Labrador Sea Water (LSW), the Iceland–Scotland Overflow Water (ISOW) and the Denmark Strait Overflow Water (DSOW). The Antarctic Bottom Water (AABW) is the only natural water mass in the bottom layer, and this water mass is redefined as Northeast Atlantic Bottom Water (NEABW) in the north of the Equator due to the change of key properties, especially silicate. Similar with NADW, two additional water masses, Circumpolar Deep Water (CDW) and Weddell Sea Bottom Water (WSBW), are defined in the Weddell Sea region in order to understand the origin of AABW.

Download Full-text

Mixing Trajectories of Intermediate Depth Waters of the South-East Indian Ocean as Determined by a Salinity Frequency Method

Marine and Freshwater Research ◽

10.1071/mf9630001 ◽

1963 ◽

Vol 14 (1) ◽

pp. 1 ◽

Cited By ~ 4

Author(s):

DJ Rochford

Keyword(s):

Indian Ocean ◽

Water Masses ◽

Intermediate Water ◽

The South ◽

Intermediate Depth ◽

East Indian ◽

The Core ◽

Deep Mixing ◽

Core Method ◽

East Indian Ocean

A new method for the detection of water masses and for the tracing of their mixing paths is described. Histograms of the salinity frequency distribution on 0.10 σt intervals from σt 26.90 to 27.70 contain modes which indicate the salinity characteristics of the intermediate water masses of the south-east Indian Ocean. These salinity characteristics are used to trace the extent of spreading of the water masses on these σt intervals and to determine trajectories of shallow and deep mixing. Comparison is made of the results obtained by the new method with those by the core method for the water masses and circulation in intermediate depth of the south-east Indian Ocean. The core method in this region has not been able to show the large extent of deep mixing associated with the spreading of the Banda and Antarctic Intermediate water masses. The core method has also failed to show the widespread distribution of patches of Banda water at about 400-500 m throughout the whole south-east Indian Ocean.

Download Full-text

Hydrology of the Indian Ocean. I. The Water Masses in Intermediate Depths of the South-East Indian Ocean

Marine and Freshwater Research ◽

10.1071/mf9610129 ◽

1961 ◽

Vol 12 (2) ◽

pp. 129 ◽

Cited By ~ 16

Author(s):

DJ Rochford

Keyword(s):

Indian Ocean ◽

West Indian ◽

Water Masses ◽

The South ◽

North West ◽

East Indian ◽

The North ◽

The Indian Ocean ◽

The Antarctic ◽

East Indian Ocean

Three water masses have been identified from maxima and minima in temperature-salinity diagrams for intermediate depths of the south-east Indian Ocean. (1) The Antarctic Intermediate occurred as a salinity minimum within the density range of 7.00-27.28 σt. (2) The North-West Indian Intermediate was found as a salinity maximum within the σt range 27.20-27.50. (3) The Banda Intermediate, lying below the North-West Indian Intermediate, had the characteristic of a salinity minimum within the σt range of 27.28-27.59. Preformed phosphate has been found useful as a third conservative property for the identification of major paths of spreading. The distribution and paths of spreading of the three water masses are shown in charts of the Indian Ocean east of 90�E.

Download Full-text

Aegean Sea Water Masses during the Early Stages of the Eastern Mediterranean Climatic Transient (1988–90)

Journal of Physical Oceanography ◽

10.1175/jpo2940.1 ◽

2006 ◽

Vol 36 (9) ◽

pp. 1841-1859 ◽

Cited By ~ 55

Author(s):

I. Gertman ◽

N. Pinardi ◽

Y. Popov ◽

A. Hecht

Keyword(s):

Surface Water ◽

Deep Water ◽

Water Mass ◽

Sea Water ◽

Eastern Mediterranean ◽

Aegean Sea ◽

Water Masses ◽

Intermediate Water ◽

Central Basin ◽

Cretan Sea

Abstract The Aegean water masses and circulation structure are studied via two large-scale surveys performed during the late winters of 1988 and 1990 by the R/V Yakov Gakkel of the former Soviet Union. The analysis of these data sheds light on the mechanisms of water mass formation in the Aegean Sea that triggered the outflow of Cretan Deep Water (CDW) from the Cretan Sea into the abyssal basins of the eastern Mediterranean Sea (the so-called Eastern Mediterranean Transient). It is found that the central Aegean Basin is the site of the formation of Aegean Intermediate Water, which slides southward and, depending on their density, renews either the intermediate or the deep water of the Cretan Sea. During the winter of 1988, the Cretan Sea waters were renewed mainly at intermediate levels, while during the winter of 1990 it was mainly the volume of CDW that increased. This Aegean water mass redistribution and formation process in 1990 differed from that in 1988 in two major aspects: (i) during the winter of 1990 the position of the front between the Black Sea Water and the Levantine Surface Water was displaced farther north than during the winter of 1988 and (ii) heavier waters were formed in 1990 as a result of enhanced lateral advection of salty Levantine Surface Water that enriched the intermediate waters with salt. In 1990 the 29.2 isopycnal rose to the surface of the central basin and a large volume of CDW filled the Cretan Basin. It is found that, already in 1988, the 29.2 isopycnal surface, which we assume is the lowest density of the CDW, was shallower than the Kassos Strait sill and thus CDW egressed into the Eastern Mediterranean.

Download Full-text

Water Mass Transformation and Subduction in the South Atlantic

Journal of Physical Oceanography ◽

10.1175/jpo2782.1 ◽

2005 ◽

Vol 35 (10) ◽

pp. 1841-1860 ◽

Cited By ~ 32

Author(s):

J. Donners ◽

S. S. Drijfhout ◽

W. Hazeleger

Keyword(s):

Surface Water ◽

Indian Ocean ◽

Mixed Layer ◽

Water Mass ◽

South Atlantic ◽

Water Masses ◽

Intermediate Water ◽

Tropical Atlantic ◽

The South ◽

The Indian Ocean

Abstract The transformation of water masses induced by air–sea fluxes in the South Atlantic Ocean is calculated with a global ocean model, Ocean Circulation and Climate Advanced Modeling (OCCAM), and has been compared with several observational datasets. Air–sea interaction supplies buoyancy to the ocean at almost all density levels. The uncertainty of the estimates of water mass transformations is at least 10 Sv (Sv ≡ 106 m3 s−1), largely caused by the uncertainties in heat fluxes. Further analysis of the buoyancy budget of the mixed layer in the OCCAM model shows that diffusion extracts buoyancy from the water column at all densities. In agreement with observations, water mass formation of surface water by air–sea interaction is completely balanced by consumption from diffusion. There is a large interocean exchange with the Indian and Pacific Oceans. Intermediate water is imported from the Pacific, and light surface water is imported from the Indian Ocean. South Atlantic Central Water and denser water masses are exported to the Indian Ocean. The air–sea formation rate is only a qualitative estimate of the sum of subduction and interocean exchange. Subduction generates teleconnections between the South Atlantic and remote areas where these water masses reemerge in the mixed layer. Therefore, the subduction is analyzed with a Lagrangian trajectory analysis. Surface water obducts in the South Atlantic, while all other water masses experience net subduction. The subducted Antarctic Intermediate Water and Subantarctic Mode Water reemerge mainly in the Antarctic Circumpolar Current farther downstream. Lighter waters reemerge in the eastern tropical Atlantic. As a result, the extratropical South Atlantic has a strong link with the tropical Atlantic basin and only a weak direct link with the extratropical North Atlantic. The impact of the South Atlantic on the upper branch of the thermohaline circulation is indirect: water is significantly transformed by air–sea fluxes and mixing in the South Atlantic, but most of it reemerges and subducts again farther downstream.

Download Full-text

Water mass distributions and transports for the 2014 GEOVIDE cruise in the North Atlantic

10.5194/bg-2017-355 ◽

2017 ◽

Cited By ~ 1

Author(s):

Maribel I. García-Ibáñez ◽

Fiz F. Pérez ◽

Pascale Lherminier ◽

Patricia Zunino ◽

Paul Tréguer

Keyword(s):

North Atlantic ◽

Water Mass ◽

Sea Water ◽

Water Levels ◽

Water Masses ◽

Meridional Overturning Circulation ◽

Labrador Sea ◽

Intermediate Water ◽

North East ◽

Relative Contribution

Abstract. We present the distribution of water masses along the GEOTRACES-GA01 section during the GEOVIDE cruise, which crossed the subpolar North Atlantic Ocean and the Labrador Sea in the summer of 2014. The water mass structure resulting from an extended Optimum MultiParameter (eOMP) analysis provides the framework for interpreting the observed distributions of trace elements and their isotopes. Central Waters and Subpolar Mode Waters (SPMW) dominated the upper part of the GEOTRACES-GA01 section in 2014. At intermediate depths, the dominant water mass was Labrador Sea Water, while the deep parts of the section were filled by Iceland–Scotland Overflow Water (ISOW) and North East Atlantic Deep Water. We also evaluate the water mass volume transports across the 2014 OVIDE line (Portugal to Greenland section) by combining the water mass fractions resulting from the eOMP analysis with the absolute geostrophic velocity field estimated through a box inverse model. This allowed us to assess the relative contribution of each water mass to the transport across the section. Finally, we discuss the changes in the distribution and transport of water masses between the 2014 OVIDE line and the 2002–2010 mean state. At the upper and intermediate water levels, colder end-member of the water masses replaced the warmer ones in 2014 with respect to 2002–2010, in agreement with the observed cooling of the surface and intermediate waters. Below 2000 dbar, ISOW increased its contribution in 2014 with respect to 2002–2010, increase related to the observed salinization since 2002. We also observed an increase in SPMW in the East Greenland Irminger Current in 2014 with respect to 2002–2010, which supports the recent deep convection events in the Irminger Sea. The assessment of the relative contribution of each water mass to the Atlantic Meridional Overturning Circulation (AMOC) across the OVIDE line allows identifying the water masses involved in the increase in the AMOC intensity from 2002–2010 to 2014. The increase in the AMOC intensity is related to the increase in the northward transport of the Central Waters in its upper limb, and to the increase in the southward flow of SPMW of the Irminger Basin and ISOW in its lower limb.

Download Full-text