Ocean Circulation and Structure

Fig. 10-14, p. 271

Major ocean circulation Gyres: clockwise in Northern Hemisphere and counter clockwise in southern hemisphere

Gyres

Table 10-1, p. 271

Know the currents in the red boxes.

Fig. 10-15, p. 272Gulf stream is a western boundary current

Florida Current

EOS(American Geophysical Union)

Volume 92 number 318 JANUARY 2011pages 21–28

EOS(American Geophysical Union)

Volume 92 number 318 JANUARY 2011pages 21–28

Fig. 10-16, p. 273

Upwelling of cold nutrient rich water

Fig. 10-17, p. 273

Upwelling of cold nutrient rich water is a result of the Ekman Spiral. The prevailing winds, frictional drag, and the coriolis force all work together to given an average surface transport of ocean waters in a direction 90 degrees to the right in NH (left for SH) from surface winds

Fig. 10-18, p. 274

Upwelling bring cool nutrient rich waters to the surface.

The Gulf stream is considered to be a western boundary current. It is relatively narrow and fast. (it is found on the western boundary of the Atlantic ocean)

The California current is considered to be a eastern boundary current. It is relatively wide and slow moving. (it is found on the eastern boundary of the Pacific ocean)

Why western boundary currents are fast and tight.

Vertical Structure

Know what the surface zone and thermocline are.

CTD instrument Conductivity, Temperature, Depth

Each time one goes down 10 meters in the ocean the pressure increases by 1 Atmosphere (1 Bar). 1.0 decibars=1.0 meter

Circle the best choices.

Temperature normally (increases/ decreases) with depth.

Salinity normally (increases/ decreases) with depth.

Density normally (increases/ decreases) with depth.

Circle the best choices.

Temperature normally (increases/ decreases) with depth.

Salinity normally (increases/ decreases) with depth.

Density normally (increases/ decreases) with depth.

Many of the world's largest ocean trenches are located along the "Ring of Fire," an arc of volcanoes around the Pacific Ocean that denotes convergent plates margins (Fig. 3).

Thermal Haline Circulation

Ocean downwelling driven by cold salty water of North Atlantic

Ocean temperature and salinity combine to determine the density of sea water.Cold salty water is very dense and sinks.

Salinity is controlled by the difference between evaporation and precipitation as well as fresh water discharge from rivers and glacial melt.

Positive feedback for ocean salinity

Ocean salinity is typically around 35 parts per thousand 35 %0 and made up primarily of sodium chloride (table salt).

Atlantic is saltier than the Pacific

The mediterranean outflow contributes significantly to the salinity of the Atlantic. The mediterranean has become saltier in recent times as more of the fresh water feeding it is used up before reaching the mediterranean.

NADW North Atlantic Deep waterAABW Antarctic Bottom Water

Near Bottom 14C %o

Larger differences between surface water and deep water suggest “older” water. These water age estimates suggest that the north Atlantic is the primary driver of the global oceanic conveyor belt.

Ocean temperature and salinity combine to determine the density of sea water.Cold salty water is very dense and sinks.

Salinity is controlled by the difference between evaporation and precipitation as well as fresh water discharge from rivers and glacial melt.

Change in the position of continents over the past 200 million years (or more) has influenced global oceanic circulation and global climate.