final study guide

final study guide - Week 6 (new) What primary physical...

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Week 6 (new) What primary physical factors control density of seawater and therefore drive the vertical circulation of deep water? In other words, what drives thermohaline circulation? Vertical currents are driven by density (thermo = temp, haline = salinity), low temp + high salinity = more dense, gravity pushes denser water to the bottom and less dense water rises vertical circulation; caused by the process of heating in the lower latitudes close to equatorial regions, and cooling in the higher latitudes near the polar regions What processes act in the ocean to alter the density of seawater? Denser water created by: cooling of surface water (more heat given to atmosphere), increasing salinity by evaporation, formation of sea ice, & mixing water w/ different salinity & temp; rain adds water, ice & evaporation remove water to increase salinity Where do you expect these processes to occur? Densest water is deepest, formed by surface conditions that made water cold & salty (high latitudes & where evaporation is higher than precipitation), surface water masses are warmer and lower salinity, intermediate water is in between the 2. Upwelling & downwelling effect density of water, upwelling = by equator, west coast of US, South America, & Africa, Where does deep water form in the ocean, and why there? Antarctic bottom water = most distinctive deep water mass, 34.7% salinity & -0.5C temp & 1.03 density (densest water in the world); migrates north along sea floor, forms in Weddell Sea during winter, salt concentration mixes w/ frigid water rapidly; dense bottom water also forms in northern polar ocean but topography of Arctic Ocean prevents it from escaping except thru deep channels formed by submarine ridges near Scotland, Iceland & Greenland, known as North Atlantic deep water, forms when relatively warm & salty north Atlantic ocean cools as cold winds from northern Canada sweep over it, heat is released & water sinks; several other deep water masses near poles What route does deep water take to fill the oceans, where does it mix (and with what) along the way, and how long does it take to reach its destination? Antarctic bottom water travels north, very slowly (faster in Atlantic than Pacific); as it sinks toward continental shelf it mixes with nearly equal parts of water from southern Antarctic circumpolar current; moves from poles to equator in roughly 20 years What is tritium and how does it relate to the circulation of the ocean? Radioactive form of hydrogen, released by nuclear tests, isotopes can be used to examine ocean circulation & How is it that two water masses can have the same density, but different salinities? Different combinations of temp & salinity can make same density
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final study guide - Week 6 (new) What primary physical...

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