EOSC 314 - Lesson 8: Tides

Ekman Spiral

ocean acts as system with think stacked layers of water; wind blows on surface layer which moves it 45 degrees left or right of wind direction, lower layer moves 45 but less far and so on

sum of all layers water trajectory is 90 degrees

ekman transport

flow of water at 90 degree angle of wind direction (sum of all layers)

ekman transport in northern hemisphere

90 degrees right of direction of motion

how are gyres formed

through trade winds and westerlies converges water at a boundary, gravity acts on it → equilibrium is reached between gravity and Coriolis effect (wind) and water travels around the mound rather than up (geostrophic flow)

geostrophic flow

force of coriolis effect and gravity are equal/balanced and oposite

gyre if earth stopped rotating

all coriolis effect would be gone → winds go from equator to pole → convergence of water at poles + undercurrent back to equator (gyre forms at poles)

gyres if earth rotated in opposite direction

direction of flow flips + center of gyre on east

gyre if earth had no continents

2 big gyres idk

western boundary current

east west asymmetry in gyre center due to earths rotation; pole bound current; transports warm water, travels deeper and faster than other gyre currents

cold water eddys

generated from east southeast gulf; pinches off cold nutrient rich coastal zone water; rotates anti clockwise diverging water away from core = upwelling

warm water eddys

generated from west to north of gulf, rotates clockwise = water up hill = warm water pushed below (down welling)

coastal upwelling areas

coast of vancouver, california, chile, west africa (all west coasts)

coastal upwelling formation

northerly winds blow (in northern hemisphere) current is drawn away from shore → water below comes up to replace it

equatorial upwelling

caused by SE TRADE WINDs crossing equator to NH and its current veering right (in SH it goes left) creates a divergence of currents = water from below pycnocline replaces it