APES Oceanography Notes - Shope

The formatting here sucks, but I have it nice and pretty (in outline form) with diagrams of the currents if anyone is interested... and if anyone has any questions about this section, let me know. I am obsessed with oceanography. :)

• surface currents are caused by wind (and friction)
• deep currents are caused by density (caused by temperature and salinity): thermohaline circulation; (a.k.a. density currents)

• distribution of water:
o 71% of the Earth is water
o 97% is sea water (salty)
o 3% is freshwater
o 2.997% of which is unavailable for human use (ice, etc.)
o 0.003% available for human use

• salts and ocean water
o about 3.5% of ocean water is composed of salt (saline)
o 85% of that is NaCl (regular table salt)
o also: magnesium, sulfur, calcium, potassium

• the bottom of the ocean is basically a nutrient sink… aquatic organisms die and remains fall to bottom

• aquatic biomes: marine (saltwater) or freshwater
• coastal biomes
o estuaries: main breeding grounds
o marsh: coastal wetlands
o tidal pools: intertidal

• ENSO (El Niño Southern Oscillation) (“baby boy”)
o not an upwelling
o southern trade winds blow warm equatorial water away from South America and towards Asia as they blow northwest (usual)
o this allows the Peruvian current to upwell with cold, nutrient rich water
o ENSO suppresses upwelling (usual)
o generally happens around Christmastime
o warm water returns toward South America (warm air & clouds return too)
o thermocline is lowered
o less nutrients… less phytoplankton… less fish
o air pressure change: low to South America
o occurs roughly every 3-7 years (hasn’t happened in a while)
o provides fuel for evaporation & storm centers in North America… (ex. ENSO in 1998 caused a lot of snow in Charlotte)
o North American climatologists “discovered” it in 1960s… fishermen in South America had known for 100s of years
o weakens trade winds
o ties into monsoon season in Asia (more monsoons)
o cause of ENSO unknown

• La Niña (“baby girl”)
o increase in normal patterns

• tides
o the diurnal (daily) cycle of water movement caused by lunar gravity and modified by solar gravity
o tides vary with the moon’s distance in orbit and with coastal features
o occur at intervals of about six ours each day on most ocean coasts
o really only has noticeable effect on oceans
o hardly any effect on climate, but has big ecological effects
o not constant day to day because of orbits and coastal features

• types of tides
o high & low
o flood – incoming, low to high
o ebb – outgoing, high to low
o spring – highest tide (MEMS)
o neap – lowest tide

• tide frequency
o diurnal – one of each per day
o semidiurnal – two of each per day
o mixed – one & two or two & one

• waves
o the passing of a wave is essentially a transfer of energy
o the water within the wave moves in a circular pattern
o the depth of movement (a.k.a. the depth of the wave) is equal to 1/2 the wavelength
o a wave will “break” when the depth of the wave is about 1/20 the wavelength

• west wind drift – circles Antarctica (a current)