CEE 1030 1nd Edition Lecture 21: OceansOutline of Last Lecture I. Land-sea boundaryII. WavesIII. Shore zonesIV. Wave erosionV. BeachesVI. Coastal featuresVII. Wave refractionVIII. Shoreline stabilizationOutline of Current Lecture I. SalinityII. Movement of ocean waterIII. Ocean zonesIV. Seawater densityV. Tidal currentsVI. ReviewCurrent LectureI. Salinitya. Salinity: the concentration of dissolved salts in seawaterb. Ocean water has an average salinity of 3.5%c. Sodium is leached out of seafloor sedimentsd. Chloride from outgassing of underwater volcanoese. Salts leached out of terrestrial sediments by rainfall and carried to sea by runoff and groundwaterf. Variations in salinityi. Less saline where freshwater runoff mixes with seawaterii. More saline in areas with high evaporation and low precipitation and inflowII. Movement of ocean watera. World ocean: the interconnected saltwater surrounding continents and filling Earth’s deepest basinsb. Ocean current: any more or less continuous, directed movement of ocean waterc. Forces: Earth’s rotation, wind, temperature, and salinity differencesd. Influences: shape of ocean basin, seafloor topography, shoreline shape, etc.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.e. Water at different depths often moves in different directions, affected by different forcesf. Oceanographyi. Surface waters are mixed and moved by the wind, tides cause differences in densityii. Most deep ocean currents are driven by density differences in water, Coriolis effectIII. Ocean zonesa. Mixed layer: surface zone of ocean warmed by the sun and mixed by wind and wavesb. Pycnocline: the transition zone of abrupt vertical density changei. Density gradient caused by difference in water temperature or salinityc. Pelagic zone: all open ocean not near coast or seafloord. Benthic zone: water near to the coast or sea floorIV. Seawater densitya. Density: the mass of water per unit volumeb. Saltwater is denser than freshwaterc. Cold water is denser than warm waterd. Thermohaline Circulationi. Deep ocean currents are driven by density differencese. Downwelling: water sinks because of converging currents or because surface water is denser than deep waterf. Upwelling: deep water rises because it is less dense than surface waters, or pulled up to replace surface water driven away by windsi. Marked by extremely cold water temperatures and high nutrient contentii. Along western coasts of continents where equatorial winds drive surface waters awayV. Tidal currentsa. Gravitational pull of the moon and the sun cause alternating, horizontal movement of surface waterb. Typesi. Flood current: movement of water toward the shoreii. Ebb current: movement of water away from the shorec. Daily tidesi. Moon’s gravitational pull causes oceans to bulge simultaneously on moon’s nearside and farsideii. Moon’s direct gravitational pull causes oceans to bulge on Earth’s nearsideiii. Gravity decreases with distance, so moon’s gravitational pull is stronger on Earth’s nearsideiv. Stretches the planet very slightly, resulting in a tidal bulge on Earth’s farsided. Causes of tidesi. Earth rotates on its axis more rapidly than the moon’s position changesii. Tidal bulges stay in place while the planet rotates through themiii. Most coasts experience two high tides and two low tides each daye. Tidal cyclesi. Spring tides: highest of tidal range, near time of new and full moons whengravitational forces of the moon and sun are added togetherii. Neap tides: lowest tidal range, occurs near times of first and third quarters of the moon, when gravitational forces of the moon and sun are offsetf. Tides are influenced by the shape of a coastline, topography of the ocean floor, and other currentsg. Whirlpool: swirling water produced where opposing currents meet, often caused by tidesh. Maelstrom: particularly powerful whirlpooli. Eddy: circular current at the ocean surface, larger than a whirlpoolj. Gyre: rotational circulation forms in ocean basins, centered on subtropical high-pressure regionVI. Reviewa. Earth’s rotation on its axis will cause a current going from the North Pole to the equator to: be deflected westb. The gyre in the South Pacific Ocean rotates: counter-clockwisec. The greatest force driving tides in the ocean is: the gravitational pull of the