Chapter13 - Chapter 13 The Oceans, Coastal Processes, and...

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Chapter 13 The Oceans, Coastal Processes, and Landforms The Oceans Importance of oceans: fishing, commerce, trade routes, tourism About 40% of world’s population lives within 100 km (62 miles) of coastlines In U.S., 50% of population lives in “coastal” areas – includes coasts of Great Lakes Seawater Water is “universal solvent” 57 of the 92 elements can be dissolved in it Seawater is a solution: water and dissolved elements or compounds Salinity – concentration of dissolved solids Measured as %0 or parts per thousand 99% of dissolved solids in seawater made up of 7 elements: Chlorine, sodium, magnesium, sulfur, calcium, potassium, bromine Also contains dissolved gases – carbon dioxide, nitrogen, oxygen Dissolved organic matter and trace elements Average salinity of seawater is 35%0 (35 parts per thousand) Worldwide, salinity varies from 34%0 - 37%0 In equatorial waters, diluted by all the rain – 34.5%0 Subtropical oceans have lots of evaporation, salinity more concentrated – 36%0 Seawater Brine: water with greater than 35 %0 salinity Brackish: less than 35%0 salinity Lower salinity near landmasses due to freshwater runoff/river discharges Baltic Sea/Gulf of Bothnia: 10%0 Persian Gulf: 40 %0 Pockets in floor of Red Sea & Mediterranean Sea: 225 %0 Dead Sea: over 300 %0 Oceans and Seas Oceans are larger Sea is generally near a landmass Sometimes ‘sea’ refers to large, inland body of water, e.g. Salton Sea
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Pacific Ocean is world’s largest Ocean’s Physical Structure Surface warmed by sun – top zone is a mixing zone Thermocline transition zone : rapid temperature loss Deep cold zone : temps near 0 o C, but water does not freeze due to salinity Littoral Zone Littoral zone – refers to coastal environment Extends to part of land – highest water line due to storm activity Seaward to depth of about 60m – where waves can no longer move sediments on floor Mean Sea Level Sea level difficult to measure – temporal and spatial variation Mean sea level measurement based on measurements over period of at least 19 years – average tidal levels, recorded hourly Calculated at 40 locations in U.S. Satellites use radar altimeters Sea Level Variations Maximum sea level in western Pacific Ocean In U.S., sea level of Pacific higher than Atlantic (differences in air pressure, winds, ocean currents, water density, etc.) Sea levels related to amount of ice locked up in Antarctica and Greenland ice sheets,
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Chapter13 - Chapter 13 The Oceans, Coastal Processes, and...

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