Lesson 4.3:Currents

*Refer to Chapter 11 in your Textbook

Learning Goals:

1. I can differentiate between the various types of ocean currents.

2. I can describe the effect of coriolis on ocean currents.

Currents “Rivers of the sea”2 types:

1. Surface Currents (10% of all currents)• Approx 0-400 m (1,300 ft) depth• Driven by horizontal wind circulation

2. Deep Currents (90% of all currents)• Driven by vertical thermohaline

circulation• Thermo = temp, haline = salt

Surface Currents Map

Normal Sea Surface Temperature:

SST without Currents:

Surface Boundary Currents:Eastern

ColdWideShallowSlow

WesternWarmNarrowDeepFast

GyresGyre is a large circular flow of ocean water,

or current located in each ocean basin 5 major:

NAtlanticSAtlanticNPacificSPacificIndian

CoriolisCoriolis is the effect of Earth’s rotation (the

apparent deflection) on moving objectsClockwise in the Northern hemisphereCounterclockwise in the Southern hemisphere

Temporary Surface Currents: Some surface currents occur temporarily because of wind and the topography of the beach/ocean floor: 1. Longshore Currents2. Rip Currents3. Upwelling Currents

Temporary Surface Currents: Longshore currents occur parallel to

shore because of wavesCan be harmful to beaches by causing

erosion

Temporary Surface Currents: Rip currents occur perpendicular to

shore because of wind, waves, and other currents

Can be dangerous by pulling you out to sea

Temporary Surface Currents: Upwelling currents occur due to the rising of

cold, nutrient rich waterThis is very important to coastal ecosystem productivity

Deep Ocean Currents:Density controls deep ocean currents

Colder temp + Higher Salinity = Greater Density

Global Conveyer BeltA system of deep ocean currents that

connects all of the world’s ocean basins

Global Conveyer Belt: