…vast surface currents that redistribute the planet’s 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 isn’t the only thing that affects density…so 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 Ocean…depending 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 strait…INTO the sea. Sure…given enough time, the levels would equalize but on earth, in a matter of mere hours…

…it’ll be Low Tide, and the levels in the open sea drop below levels found inside the sea…and the current reverses itself…rushing 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