PHYSICAL OCEANOGRAPHY Part 3: Heat Budget & Ocean Currents GEOL 1033 (Lessons 27-28, 33, & 34) Ppt file 103 - 24

EARTH'S HEAT BUDGET About half of solar radiation, mostly as visible light, reaches Earth's surface Re-radiated energy is in the form of infrared radiation Carbon dioxide and water vapour temporarily absorb some of this infrared (=greenhouse effect & global warming) half Infrared radiation = heat

LATITUDINAL VARIATIONS IN SOLAR RADIATION High latitudes receive less solar energy per unit of surface area

LATITUDINAL VARIATION IN HEAT GAINS AND LOSSES Heat gains are greatest at lower latitudes Heat losses are relatively greater at higher latitudes Heat is redistributed by air & ocean currents

Global Air Circulation Cells Wet Dry Wet Dry Wet

Major Surface Wind Patterns Simplify this model & look at surface winds Winds are mainly responsible for surface ocean currents

Coriolis Effect in Northern Hemisphere Shifts winds & ocean currents to the right Related to faster surface rotation rates near the equator in comparison to those at higher latitudes

Influences on Oceanic Gyre Formation Winds cause currents Currents redistribute heat from Sun Coriolis effect shifts current directions to right in N. Hemi. & left in So. Hemi. Continents block pure E-W flow, creating boundary currents Some gravitational influence Northern Subtropical gyre

North Atlantic Gyre System Know these currents Western boundary currents (e. g., Gulf Stream) are deeper, narrower, and faster than eastern boundary currents (e. g., Canary Current) Review Lessons 33 & 34

Major Ocean Surface Currents & Climatic Zones Review Exercise #15 (Completed answer sheet on page 235 is due next Thursday, Dec. 2nd.)

Circum-Antarctic Surface Circulation Less interference from north-south oriented continental masses

REMEMBER THE PYCNOCLINE Halocline refers to the salinity increase coinciding with the thermocline Pycnocline is the density change associated with the thermocline and halocline

Surface zone Pycnocline Deep zone REMEMBER LATITUDINAL VARIATIONS IN AVERAGE DEPTH OF VERTICAL DENSITY ZONES Surface zone Pycnocline Deep zone

PACIFIC OCEAN Salinity/Temperature Structure

ATLANTIC OCEAN Salinity/Temperature Structure

Circulation of Atlantic Ocean Water Layers Note Antarctic Intermediate and Bottom Waters Find the North Atlantic Deep Waters AC = ? AD = ?

Antarctic Ocean Upwelling and Downwelling North Atlantic Deep Waters

Stopped Here

Ekman Spiral Due to Coriolis effect, can get a weak countercurrent at depth

Northern Hemisphere Coastal Upwelling and Downwelling Coriolis right shift of surface waters (Ekman spiral effect) Onshore to produce downwelling Offshore to produce upwelling

Southern Hemisphere Coastal Upwelling and Downwelling Coriolis left shift of surface waters (Ekman spiral effect) Onshore to produce downwelling Offshore to produce upwelling El Nino off NW coast of So. Am.

Circulation of Atlantic Ocean Water Layers Note Antarctic Intermediate and Bottom Waters Find the North Atlantic Deep Waters Note Med. Salty, warm water AC = ? AD = ?

The Oceanic “Conveyor Belt” Thermohaline surface to deep planetary circulation system. A disruption may bring on another Ice Age!

END OF FILE