Castex Period 1 - Group 5 Mery Llano, Marian Pedreira , Kimberly Lara Deepwater Castex Period 1 - Group 5 Mery Llano, Marian Pedreira , Kimberly Lara

When and how do the distinct deep-water masses of the ocean form? Two deep masses, Antarctic Bottom Water and North Atlantic Deep Water, make up most of world’s deep waters. Densest water forms in Antarctic during winter. Antarctic Bottom Water salinity 34.65% 31 degrees F, 3% higher density than freshwater. High density ---low temperature & high salinity. Primary source of deep and bottom water is from high latitudes due to freezing and cooling raising the salinity and density. How Deep Water forms When and how do the distinct deep-water masses of the ocean form?

How do they form? Seawater freezes and leaves salt behind, and the water that remains becomes saltier, that is why Atlantic Bottom Water has high salinity. In the Arctic, deep water forms as high salinity surface water cools and sinks. Much of the North Atlantic Deep Water that forms is trapped by the topography of the Arctic Ocean. Some escapes into the Atlantic through deep channels around Scotland, Ireland, and Greenland, but none enters the Pacific due to landmass and restriction at the Bering Strait. Contour currents-bottom currents influenced by topography. Flow of Atlantic Deep Water- After its formation off Greenland and other polar regions, very dense water follows the contours of the seafloor.

Mediterranean Deep Water Forms due to evaporation rather than cooling. The high evaporation rate in the Mediterranean raises salinity, so that during the winter MDW with a salinity 38% flows through the strait of Gibraltar into the Atlantic. The water is saltier than Antarctic Bottom Water, but warmer and not as dense. Rests above the bottom and deep layers as intermediate water. Mediterranean Deep Water

Water masses- Cross-section of the entire Atlantic Ocean looking eastward. Note how the different water masses float or sink, depending on their relative density. Circulation patterns are also shown.

Deepwater Flow Patterns The thermohaline circulation pattern consists of huge water quantities that sink at the poles and in the Mediterranean. Dense water tends to descend quickly into deep areas, displacing and mixing with the water already there. As deep water is mixed upwards it warms up. Deepwater Flow Patterns What is the general pattern of thermohaline circulation?

Deepwater Flow Patterns When it rises close enough to the surface to enter wind-driven currents, it is carried to higher latitudes. Once its there, it cools down, becomes more dense, and sinks again. Deepwater Flow Patterns What is the general pattern of thermohaline circulation? (Continued)

Thermohaline Circulation Pattern Note how the deep water is formed in polar regions and then dispersed, eventually rising to the surface as it warms, keeps it stable. Otherwise, the thermocline in low latitudes would progress deeper and deeper.

Deepwater Flow Patterns (Continued) Thermohaline circulation redistributes heat throughout the oceans, moderating both warm and cool areas. Without thermohaline circulation, tropical regions would continue to warm, driving the thermocline deeper and deeper. Polar regions would continue to freeze until the ice caps reached the sea bottom.

The Ocean Conveyer Belt Defined as the interconnected flow of currents that redistribute heat, Earth’s “airconditioner.” Pattern: North Atlantic Deep Water flows south along the Atlantic bottom, merging with the Atlantic Bottom Water. Then, flows eastward mostly to the South Pacific. As water warms and rises, eventually reaches the surface. From there, pushed by trade winds into five ocean gyres, carries heat from equatorial regions towards the poles, cools/descends and repeat. The Ocean Conveyer Belt What is the conveyor belt phenomenon? Why is it important?

Ocean Conveyor Belt- Carries heat away from the tropics and keeps them from getting too hot.

Why is it important? Moderates the world’s climate and redistributes heat Some scientists hypothesize that some of the coldest intervals within ice ages have resulted from disruption of the ocean conveyor belt. They hypothesize that dilution of the Artic Ocean and North Atlantic Ocean with excess fresh water decreases the sinking of North Atlantic Deep Water. Global warming may lead to an ice age, melting ice caps dilutes seawater preventing the high density salt water from forming, no downwelling to feed deep water currents, disrupt conveyor belt. Would cause large parts of Northern Hemisphere, Europe, to be much colder.

https://www.youtube.com/watch?v=fH1U PruZ2YQ Video https://www.youtube.com/watch?v=fH1U PruZ2YQ

Multiple Choice Quiz ! Thermohaline circulation is water movement caused by The wind Pelagic organisms Water density differences 2. The primary source of deep and bottom water is from The equator due to evaporation raising the salinity and density. High latitudes due to freezing and cooling raising the salinity and density. None of the above 3. The ocean conveyor belt is important because It is the primary method fishermen have to process what they catch It redistributes heat and moderates the Earth’s climate

"Ocean conveyor belt. " YouTube. YouTube, 20 Nov. 2016. Web. 31 Mar "Ocean conveyor belt." YouTube. YouTube, 20 Nov. 2016. Web. 31 Mar. 2017. <https://www.youtube.com/watch?v=fH1 UPruZ2YQ>. Troyer, Matthias. "The world of H.C. Berann." The panoramas of H.C.Berann. N.p., n.d. Web. 31 Mar. 2017. <http://www.berann.com/panorama/inde x.html#ocean>. "What is the thermohaline circulation (THC)?" Thermohaline Circulation - Fact Sheet by Stefan Rahmstorf. N.p., n.d. Web. 31 Mar. 2017. <http://www.pik- potsdam.de/~stefan/thc_fact_sheet.html >. Bibliography