vast surface currents that redistribute the planets heat Rotating CLOCKWISE in the northern hemisphere & COUNTER- CLOCKWISE in the southern To summarize GYRE (aka surface) A combination of the Coriolis Effect and predominant wind patterns Vast circular currents that rotate clockwise (north of the equator) moving heat/life across ocean basins* Gulf Stream EAC California Kuroshiro *at the rate of 100 miles/day (5 mph) SALT WATER Adding NaCl to water increases its density, causing the saltier water to sink Of course, salt isnt the only thing that affects densityso does temperature! Hot air rises Cold(er) air (water!) sinks When heat-alone it is aka a convection current Both of which affect the DENSITY So you need to INCREASE the DENSITY of the Ocean THERMOHALINE (aka Density) ..and there are only a couple ways to do that EVAPORATION FREEZING Changes in TEMP or SALINITY increase the DENSITY of the water generating a slow*, deep sea current *3 meters/day Colder, saltier water sinks to the seafloor, creeping along the bottom The strongest are created at the poles, AABW: Antarctic Bottom Water The FRESH WATER plume generated by the Amazon River extends HUNDREDS of miles out into the Atlantic Oceandepending on sea surface conditions the uppermost layer (often only a few centimeters deep) remains drinkable. GYRE & DENSITY? One runs across the ocean surface while the other moves vertically through the depths of the ocean SURFACE CURRENTS VERTICAL CURRENTS LONGSHORE Waves refracted at the shoreline A modest yet persistent current moving PARALLEL to the beach (0.05 mph) Once rock from the nearby (Olympic) mountains has eroded, it is transported by river currents to the sea Transports sand south*, building spits at the mouth of harbors *or north on the east spits During High Tide, the levels in the open sea exceed the levels found inside enclosed areas (seas) creating a STRONG current as water rushes through the straitINTO the sea. Suregiven enough time, the levels would equalize but on earth, in a matter of mere hours itll be Low Tide, and the levels in the open sea drop below levels found inside the seaand the current reverses itselfrushing through the strait OUT of the sea TIDAL The inability of straits to keep up with changes in tidal levels HIGH tide LOW tide Swift, strong* currents passing through straits that reverse direction several times a day. Gibralter (Med), Juan deFuca (Salish), Tacoma Narrows *Up to 20 mph Colder, denser water Warmer, less dense water Typical on-shore winds Periodically, coastal weather patterns change, reversing to an OFF-shore direction Off-shore winds develop As the winds transfer their energy to the sea, the typically-warmer surface waters are pulled away from the coast only to be replaced by the colder waters that are usually resigned to the abyssal depths. Warm waters Abyssal plains are typically high in nutrients, the result of (eons of) runoff from the continents Cold, nutrient-rich waters return to the surface Nutrients feed a plankton bloom UPWELLING Off-shore winds cause deep-sea waters to flow toward the surface, moving UP the continental slope WIND Can also be caused by volcanic activity on the seafloor Cold, nutrient-rich waters returned to the surface, setting off oceanic food chains Typically occur along eastern basins every autumn, called the Fall Overturn * * Loihi, Axial Seamount