An oceanographic water mass is an identifiable body of water with a common formation history which has physical properties distinct from surrounding water. Properties include temperature , salinity , chemical - isotopic ratios, and other physical quantities which are conservative flow tracers . Water mass is also identified by its non-conservative flow tracers such as silicate, nitrate, oxygen, and phosphate.
8-716: The Overturning in the Subpolar North Atlantic Program ( OSNAP ) is an international project designed to study the mechanistic link between water mass transformation at high latitudes and the meridional overturning circulation in the North Atlantic ( AMOC ) on interannual time scales. Though this linkage is evident in climate models on decadal time scales, to date there has been no clear demonstration of AMOC variability in response to changes in deep water formation on interannual and decadal time scales. OSNAP intends to fill that gap by providing
16-433: A continuous record of the trans-basin fluxes of heat, mass and freshwater for a comparison to records of convective activity and water mass transformation at high latitudes in the North Atlantic. The OSNAP observing system, fully deployed in the summer of 2014, consists of moorings , gliders and RAFOS floats spanning the subpolar North Atlantic from Labrador to Greenland to Scotland. Measurement contributions come from
24-460: Is being formed in a cold climate like Antarctica, the cold temperatures separate the molecular bonds of the water causing it to become less dense. However, because water increases its volume by about 9% when frozen, this makes the ice less dense than the water which is why glaciers float. This also in turn causes the salinity of the water to decrease. The salinity of the water makes water freeze at lower temperatures than freshwater. Freshwater freezes at
32-651: Is calculated on the basis of the directly measured boundary currents , the geostrophic currents and the Ekman transports estimated from the surface wind stress . In conjunction with the RAPID/MOCHA array at 26⁰N, the EU THOR/NACLIM program and other observational elements, OSNAP will provide a comprehensive measure of the three-dimensional AMOC in the North Atlantic and an understanding of what drives its variability. The first OSNAP data products are expected in
40-743: The US, the UK, Germany, the Netherlands, Canada, China and France. Vigorous boundary currents crossing the OSNAP line are directly measured in the Labrador and Irminger Seas by current meter arrays, and over the eastern flank of the Reykjanes Ridge by deep arrays. Geostrophic currents in the basin interior are estimated using temperature and salinity measurements from moorings and gliders. The AMOC
48-586: The fall of 2017. Water mass Water masses are generally distinguished not only by their respective tracers but also by their location in the Worlds' oceans. Water masses are also distinguished by their vertical position so that there are surface water masses, intermediate water masses and deep water masses. Common water masses in the world ocean are: Although there are many types of water masses, they all share characteristics. Water Masses are formed from regions of water having different temperatures. When ice
56-473: The standard 0 °C (32 °F), while saltwater freezes at an average of -2 °C (28.4 °F). The best method of classifying a water mass is through using a T-S diagram. In the diagram pictured at the top, it categorises a water mass by the temperature and salinity of the water and is represented by a single point. However, water masses are not constant. Throughout time climates can change, seasons can drag out, or there could be less rainfall meaning that
64-402: The water masses might change in temperature or salinity. To have a complete water mass classification, it requires the water type of the source and the standard deviations of the temperature and salinity. It can take many years to establish the standard deviations of the water mass and requires constant surveillance. Once all of the necessary measures are completed, the data will now determine what
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