Ocean Circulation & Global Conveyor Belt14,15

Primary driver of surface ocean circulation

Wind friction ("fetch")

Primary driver of deep ocean circulation

Density differences caused by temperature and salinity

Percentage of total ocean volume in the surface layer

10 percent

Percentage of total ocean volume in the deep ocean

90 percent

Gyre definition

A large global system of rotating ocean currents

Gyre rotational direction in the Northern Hemisphere

Clockwise

Gyre rotational direction in the Southern Hemisphere

Counter-clockwise

Number of major subtropical gyres in the global ocean

Five

Thermal profile of western boundary currents

Warm water tracking from equatorial tropics

Thermal profile of eastern boundary currents

Cold water tracking down from polar latitudes

Velocity profile of western boundary currents

Fast flowing speed

Velocity profile of eastern boundary currents

Slow flowing speed

Depth and width profile of western boundary currents

Deep and narrow

Depth and width profile of eastern boundary currents

Shallow and wide

Cause of western boundary intensification

Earth's rotation to the east and continental barriers

Example of a western boundary current

Gulf Stream or Kuroshio Current

Example of an eastern boundary current

California Current or Canary Current

Regional climate effect of western boundary currents

Generates highly humid climates on land

Regional climate effect of eastern boundary currents

Generates highly dry or arid climates on land

Cold current adjacent to Cape Town

Benguela Current

Warm current adjacent to Durban

Agulhas Current

Flow speed of the Gulf Stream

9 kilometers per hour

Significance of Benjamin Franklin's 1786 chart

Earliest chart of the Gulf Stream tracking temperature and speed

Loop current definition

A semi-permanent warm branching arm of the Gulf Stream in the Gulf of Mexico

Spin direction of warm core rings in the Northern Hemisphere

Clockwise

Spin direction of cold core rings in the Northern Hemisphere

Counter-clockwise

Biological productivity of cold core rings

High productivity due to upwelling of nutrient-rich deep water

Ekman spiral mechanism

Successive water layers shift and slow due to Coriolis deflection and friction

Ekman transport net water movement angle

90 degrees relative to prevailing wind direction

Ekman transport deflection in the Northern Hemisphere

90 degrees to the right of the wind track

Ekman transport deflection in the Southern Hemisphere

90 degrees to the left of the wind track

Cause of equatorial upwelling

Surface waters diverge at the equator due to Ekman transport

Coastal upwelling mechanism

Offshore Ekman transport replaces surface water with cold deep water

Status of nitrate in the ocean

Non-conservative element depleted at the surface and high at depth

Thermal fingerprint of upwelling zones

Significantly colder than immediate surrounding waters

Chlorophyll a concentration proxy

Used to quantify phytoplankton primary productivity

Drivers of thermohaline circulation

Temperature and salinity differentials governing density

Polar zone water column structure

Poorly stratified and homogenous from surface to seafloor

Brine rejection definition

Salt expelled into surrounding water during sea ice formation

Primary formation location of North Atlantic Deep Water

North Atlantic near Greenland

Status of Antarctic Bottom Water

The densest water mass on Earth hugging the abyssal plain

Mediterranean intermediate water formation mechanism

Extreme evaporation creating heavy, highly saline water

TSD diagram purpose

Plotting temperature, salinity, and density to identify water masses

Mixing time of the global ocean conveyor belt

Approximately 1,600 years

1990 Nike sneaker spill result

Traced the North Pacific Current after shoes landed in Seattle

1991 rubber duck spill result

Provided precise current speed data along the Alaskan coast