Surface Currents▫Movement of water that flow in the upper part of the ocean’s surface

Surface Currents

1. Caused by friction between the ocean and the wind that blows across its surface

2.Created by the prevailing wind system

3. Currents are closely related to the general circulation pattern of the atmosphere

4. Can be localized, seasonal or permanent

The major cause of gyres is…

•the Coriolis effect – the deflection of currents away from their original as a result of the Earth’s rotation

Northern Hemisphere – deflection to the right

Southern Hemisphere – deflection to the left

Gyres

Currents and Climate low latitude currents move to high

latitudes – transferring heat from the warm to the cooler areas

High latitude currents move to low latitudes – transferring cooler water to warmer climates

Ocean water movement accounts for ¼ of heat transport on the Earth

•The Gulf Stream brings warmer water to Great Britain and Northwestern Europe

•Causes warmer winters (felt in the middle latitudes)

Upwelling Wind induced

▫The vertical rising of cooler water from deeper layers of the ocean to replace warmer surface water

▫cooler temperatures brings greater amounts of nutrients and therefore greater amount of fish and other marine life

Ocean Water Trends??????

•Temperature:

•Density:

•Salinity:

Deep Ocean Circulation•Significant vertical movement

▫Accounts for the thorough mixing of deep- water masses

Density Currents•Dense water sinks and spreads out beneath the ocean’s surface

•Increased density caused by: decrease in temperature increase in salinity

High Latitudes (decrease in temps.)

where most deep currents begin sea-ice is formed due to cold temps., leaving behind a greater salinity of remaining water, which then sinks

highest density of ocean water found near Antarctica

ocean water sinks and travels the ocean basin for some 500-2000 years

Evaporation (increases in salinity)

high temps. - increase evaporation

less water leads to greater salinity of remaining water

remaining water sinks to ocean basin and travels the globe

Conveyor Belt – Thermohaline Circulation

warm surface water flows towards the poles

at the poles water temp. drop - salinity increases making it more dense and it sinks

sinking water then moves towards the equator on the ocean floor

at the equator the water is cold and deep

deep water eventually upwells to complete the circuit –

• influences global climate by warm water releasing heat into the atmosphere

Predict:What would happen if thermohaline circulation were to stop?