Circumpolar deep water
Circumpolar Deep Water (CDW) is a designation given to the
Physical Properties
CDW, the greatest volume water mass in the
There are two types of CDW: Upper Circumpolar Deep Water (UCDW) and Lower Circumpolar Deep Water (LCDW). UCDW originates in the Indian and Pacific Oceans and has lower oxygen levels and higher nutrients than LCDW. LCDW comes from North Atlantic Deep Water and has a higher salinity.[4] In the Indian Ocean, CDW has a temperature of 1.0–2.0 °C (33.8–35.6 °F). In the Pacific Ocean, it is slightly colder with a temperature of 0.1–2.0 °C (32.2–35.6 °F).[1] The salinity of CDW is 34.62 to 34.73 ‰.[1]
Because CDW is a mix of other water masses, its temperature-salinity (TS) profile is the point where the TS lines of the other water masses converge. TS diagrams refer to temperature and salinity profiles, which are one of the major ways water masses are distinguished from each other. The convergence of the TS lines thus proves the mixing of the other water masses.[1]
Influence on Antarctic ecosystems and ice shelves
CDW plays an important role in the Antarctic Circumpolar Current (ACC) because it contributes to the melting of the base of ice shelves.[4] Glaciers ending in CDW have melted considerably while glaciers in the northwest, with no CDW, have not.[2] The CDW is salty and slightly above freezing temperature, which is warm compared to ice shelves.[4] When the CDW flows upward onto the continental shelf and travels through the deep canyons, it reaches the underside of the ice shelves. The warmer water makes contact with the shelves, contributing to the ice shelf melting.[4] Gradients around Antarctica formed between shelf water and CDW are called the Antarctic Slope Front.[3]
The CDW also plays an important role in supporting Antarctic ecosystems. Upwelling of the CDW onto the Antarctic continental shelves brings heat and nutrients that support ecosystems along the west Antarctic Peninsula.[4]
References
- ^ ISBN 9780123744739
- ^ S2CID 206646176.
- ^ S2CID 134363794.
- ^ ISSN 0967-0645.