AICE Marine: Ocean Currents & Tides

Current

a continual, directional movement of sea water

nutrients, dissolved gases, heat, and organisms

what do current carry?

Currents have a significant impact on what?

ecosystems & global climate

Currents are created by:

wind, temperature, salinity, density, Coriolis effect, and shape of seabed

two major types of currents:

surface and deep-water currents

What are surface currents driven by:

wind

It forms predictable winds, which then lead to constant surface currents at different latitudes.

What is the global result of air moving in convection currents?

How are deep currents/thermohaline circulation created:

differences in density caused by salinity and temperature

upwelling

the movement of cold, nutrient rich water from the seabed vertically to the ocean’s surface also increases productivity

what is upwelling caused by

winds forcing warmer surface water away from the coastline, creating low pressure zones that bring cold water to the surface

downwelling

the driving force of the conveyor belt and pushes surface currents down into deeper layers of the ocean.

Thermohaline circulation

is a massive slow moving system of deep ocean currents driven by differences in water temperature and salinity

higher salinity & lower temperature making the water more dense and sinks

what is downwelling?

global conveyor belt

what is another name for the thermohaline circulation

why is the global conveyor belt important

it regulates our climate

The warm water of the Gulf stream is heated by the equator, then flows north to the Arctic.

1st step of the formation of the global conveyor belt

in the Arctic, the cold-water freezes into sea-ice, leaving water saltier and colder

2nd step of the formation of the global conveyor belt

higher salinity and cold water makes it denser so it sinks(downwelling)

3rd step of the formation of the global conveyor belt

water reaches bottom, begins to move south through Atlantic ocean towards Antarctica

4th step of the formation of the global conveyor belt

in Antarctica the global conveyor belt picks up cold nutrient rich water bringing nutrients to the eastern coast of Africa

5th step of the formation of the global conveyor belt

currents move northward to Indian & Pacific oceans where it is warmed and returns as surface currents

6th step of the formation of the global conveyor belt

sea ice adds fresh water to the ocean which decreases the salinity and density of the water. This reduces downwelling which is needed for the global conveyor belt

How does the melting of ice sheets impact the global conveyor belt?

Tides

the regular rise and fall of bodies of water as dictated by the gravitational interactions between the Moon, Earth, and Sun

The variance in tidal range is due to?

The gravitation effects of the Moon, Earth, and sun, and physical features of the coastline

what is a spring tide and when do they occur

the time of greatest tidal range,and they occur during new and full moon

what are neap tides and when do they occur

the time of least tidal range and occur during first and third quarter moons

what factors affect the height of a spring tide

wind direction, wind speed, air pressure, shape of coast, shape of seabed

what is a tidal surge and how are they created

a dangerous rising of water higher than the predicted levels of the tide. It is created by high winds and low pressure

what is a tidal range

the difference in height between a low -water make and the high water mark on a coastline

Semidiurnal

when tidal patterns have two high tides and two low tides each day

diurnal

a tidal pattern one high tide and one low tide each day

Humboldt current

cold water current with low salinity levels that flow north along the western coast of S. America, also known as the Peru current

which was do the surface currents move in the southern hemisphere

counter-clockwise spiral

which way to surface currents move in the northern hemisphere

clockwise spiral

what is the coriolis effect a result of

the rotation of earth

what has the worlds largest tidal range?

The bay of fundy

about 17 meters

What is the maximum spring tidal range in the Bay of Fundy

why does tidal height increase in narrow channel

water is forced into a smaller space

what is the shape of the bay of fundy

funnel shape of a basin

tidal bore

a wave of incoming tide that travels up a river or narrow channel

Ekman transport

the net movement of ocean water at a 90 degree angle to the direction of the wind