GEOS 212 1st Edition Lecture 17Outline of Last Lecture LECTURE 16 OUTLINE (Density currents ) - Review of longshore currents & transport - Review of coastline processes from wave action (erosion, longshore transport, deposition) - Shoreline Straightening Upwelling & downwelling from onshore & offshore wind - Upwelling/downwelling, waves, longshore transport, water temp, and fishing on an island - Global patterns of upwelling/downwelling and marine productivity (map info!!) - Density currents: #1: up at the equator from sun heat, down at high latitudes, turns in 100 years!- #2: Seasonal (up in summer hemisphere, down in winter hemisphere) o Driven largely by formation of ice sheets o Produces upwelling (big affect on life and migration patterns) o Very slow (~100 year rate), but never turns in complete circle. - #3 = Conveyor Belt current (important for mixing of oceans, turns in 1000 years) - Mixing time of the oceans -- main processesOutline of Current Lecture: LECTURE 17 OUTLINE (El Nino / La Nina, Hurricanes ) - Review of dynamic aspects of oceans ( keep oceans well mixed!) o -- Waves (surface layer) -- Surface currents (surface layer)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.o -- Longshore currents (surf zone)o -- Coastal upwelling/downwelling (deep & shallow water on local scale) o -- Density currents (driven by temperature and salinity): #1: up at the equator from sun heat, down at high latitudes, turns in 100 years! #2: Seasonal (up in summer hemisphere, down in winter hemisphere) Driven largely by formation of ice sheets in winter Produces upwelling in opposite hemisphere (controls migration patterns!) Slow (~100 year rate), and never turns in complete circle. #3 = Conveyor Belt current (mixes all oceans, turns in 1000 years) - Mixing time of the oceans = 1600 years!- Impact of mixing time on marine life and society - El Nino: o patterns, causes, and consequenceso history back thru time o connection to global warming?- Pattern of hurricanes in profile and map view (where up/down?)- Conditions needed for hurricanes (warm water, warm unstable air, upper level winds, not on equator) \- Hurricanes, typhoons, and cyclones (same storm in different oceans) - Hazards: (storm surge to 30 feet, heavy rains over 1” per hour, strong winds >74 to >200 mph - Hurricane tracks - Relation to global warmingCurrent
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