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Ocean Circulation
CH. 9
Question | Answer |
---|---|
Mass Flow of Ocean Water is driven by | wind and gravity |
2 main types of ocean currents | surface currents and Thermohaline currents |
Surface Currents | affects 10 % of total volume of ocean water |
Thermohaline currents | depends on density differences from variations in temp and salinity... 90% of ocean volume |
surface ocean currents that are driven by density differences in water masses | combine to transport 2/3 of total heat transferred from the equator to the poles |
100m/ 40 sec= | 2.5 m/s |
An amateur swimmer can swim 2- 2.5 mph | 1 m/s |
Surface Currents affect | 10% of oceans water (400m) |
Thermohaline currents affect | 90% volume of water |
the ocean is layered due to density differences caused by | temperture and salinity |
pynocline | 18% region of rapid increase in density |
Surface Zones | 2% well mixed of waves and currents |
Deep Zone | stable density, 80 % of water |
Geostrophic gyre | an oceanwide circular current |
Geostrophic is bounded by the | continents, westerly winds and the trade winds |
Geostrophic GYRES result from a balance of forces | wind friction, Coriolis effect and pressure gradient effect |
wind friction | in direction of wind |
Coriolis effect | as for air currents |
pressure gradient effect | gravity opposing water "piling up" downwind |
surface currents move at a | 45 angle from the wind direction. to the right in N. Hemisphere and left in Southern |
The net result is current flow at 45 to the wind direction | theory is 90 but 45 in reality |
Western Currents | are fastest, deepest and most narrowest. ex: Gulf Stream moves 2 m/s |
Eastern Currents | are slowest, shallowest and wider. example is the canary current .5 m/s |
linking the western and Eastern currents is known as | transverse currents |
transverse currents are | steady blowing westerlies and trade windes, thus continually provides energy for the ocean currents |
surface ocean currents affect | weather and climate along with winds |
surface ocean currents distribute | tropical heat worldwide |
warm water flows to | higher latitudes, thus transfers heat to the air and cools |
what is more important for warming? | winds |
vertical currents are induced by | the wind at continental edges. ex: N Hemisphere |
Interplay between ocean currents and atmospheric circulation is responsible for | El Nino and La Nina events |
Upwelling is deep oceans | brings nutrients for fish |
El Nino year | lack of wind blowing west lets warm water flow east to arrive at Peru |
El Nino is downwelling or upwelling | downwelling.. poor fishys |
Normal is when Warm water is in SW Pacific | Normal years push waters west and develop a pool of the warmest water in the world |
Normal Year (tropical pacific) | upwelling |
El Nino is when trade winds | slow and warm water starts moving |
consequences of El Nino | warm water>> increased evaporation >> increased precipitation (rain) >> flooding and a ton of nasty stuff |
El Nino lasts up how many years? | 1 |
ENSO | El Nino- Southern Oscillation |
(enSO)Southern Oscillation | periodic changes in atmospheric pressure in SW pacific |
(ENso)El Nino is a movement of warm surface water in Peru and what is resulting from it? | Weather |
LA NINA | rapid return to normal conditions. It is colder than normal events in Eastern Pacific |
El Nino Returns at 3 to what intervals? | 8 |
What percentage of the oceans water volume is affected in the Surface currents driven by wind? | 10 percent |
Denser water is usually colder and ? | saltier |
Two ways to form denser water | Freeze sea water (Arctic, Antarctic) and evaporate seawater (mediterranean) |
Freezing sea water is when the | ice is pure water, so this leaves behind saltier water (brines) |
Evaporating sea water is when the | increase of salinity, thus, hot mediterranean |
Distinctive water masses form under ice and may keep their identities for as long as | 1600 years |