Ocean Circulation

• Earth's Energy Imbalance

  • Ocean currents also transport heat to ______ latitudes

higher

• Surface Currents & Wind

  • ______: flowing band of water

  • _______ _______: exist at the surface of the ocean, down to depths of 100-400m (330-1,300 ft)

  • Atmospheric winds "push" surface waters because of ______ _____

  • Continents ______ currents

  • The ______ ______ is responsible for the circular patterns

Current; Surface currents; frictional drag; deflect; Coriolis Effect

• Gyres

  • Major surface currents display circular paths in each ocean basin/hemisphere

    • The circular currents are called _______

  • Gyres are controlled by global _____, Earth's _______, and Earth's _______

  • The rotation, clockwise (CW) in the _______ _______ and counterclockwise (CCW) in the ______ _______ is due to the Coriolis Effect

  • There are 5 major gyres:

    • North Pacific (_____)

    • South Pacific (_____)

    • North Atlantic (_____)

    • South Atlantic (______)

    • Indian Ocean (_____)

gyres; wind; rotation; landmasses Northern Hemisphere; Southern Hemisphere; CW; CCW; CW; CCW; CCW

• Eddies

  • Flow within and along _____ currents creates ______ swirls called eddies

  • _______: small, circular, temporary currents that form at the boundary of a surface current and relatively still water along it

    • Their _______ can be hundreds to thousands of km

    • Help to mix the top ~_____m (~300 ft) of the ocean

larger; smaller; Eddies; circumference; 100

A: ______

B: ______

C: _______

Wind; Surface current; Net water transport

• Ekman Spiral

  • Just like there is friction between wind and the surface of the ocean, there is ______ between layers of water

  • ______ applies a shear force to the surface layer, which applies subsequent, though lower-magnitude, shear to the layer below it

    • The motion is deflected by the ______ ______

  • Each subsequent layer rotates ______ than the layer above it

  • Frictional drag ______ with depth

  • This _____ ______ can be observed in the first ~100 m (328 ft) of the water column

friction; Wind; Coriolis Effect; more; dissipates; Ekman Spiral

• Ekman Transport (Net Water Movement)

  • Considering all the layers together, the net movement of surface water is _____ degrees deflected from the wind direction because of the ____ _____

    • This water movement is called _____ ________

  • The deflection direction is dependent upon _____ because it's controlled by the _____ _______

    • _____ _______: 90 degrees to the right

    • ______ _______: 90 degrees to the left

90; Ekman spiral; Ekman transport; hemisphere; Coriolis Effect; Northern hemisphere; Southern hemisphere

A: _______

B: _______

C: _______

Wind; Surface current; Net Water transport

• ______ _______ ______ (OST): height of the sea surface referenced against the geoid (an idealized ellipsoid that has equal gravitational pull)

  • Measured by _______

  • Variations in OST are created by _____ ______

  • Tides and waves ______ included in the OST calculation

  • The highest elevation is found in the _______ part of an ocean

Ocean surface topography; satellites; surface currents; aren't; western

• Geostrophic Flow

  • Ekman transport pushes water to the _____ of each gyre, creating a ~_____ m (3 ft) topographical high

  • Thus, the ______ ______ pushes water toward the center of a gyre

  • Water naturally flows from ____ to _____; this force is the pressure gradient

  • When the ____ (Coriolis) and ______ (pressure gradient) forces become equal and opposite, ______ ______ is achieved

  • When geostrophic balance is achieved, geostrophic current flows ________ to the slope, with stronger slopes developing _____ currents

  • ______ currents can be assumed to be geostrophic, but _______ currents may not achieve geostrophic balance

center; 1; Coriolis force; high; low; inward; outward; geostrophic balance; perpendicular; strong; Large; smaller

• Convergence & Divergence

  • Ekman transport pushes water:

    • _____: net inflow of water in an area (water masses move towards each other)

    • ______: net outflow of water in an area (water masses move away from each other)

  • Ekman transport results in:

    • _______: convergence at the center of a gyre excess water moves down

    • _______: divergence outside of the gyres, creating a void where water can undergo this to fill the gap

Convergence; Divergence; Downwelling; Upwelling

• Great Pacific Garbage Patch (GPGP)

  • Plastic is _____ dense than water, so when water ______ at the center of gyres, plastic remains ______ at the surface

  • _______ ______: high accumulations of ocean plastic, usually in the form of microplastics

less; downwells; floating; Garbage patches

• Microplastics

  • < ____mm long

  • ______ _______: released directly to the environment as small plastic pieces

  • ______ ______: form from the breakdown of larger plastic items

  • Plastics never totally break down

  • Over _____ million tonnes of microplastics have accumulated on the world's ocean floor

  • 16-35% of microplastics in the global ocean come from ________ _______

  • The _____ of textile-sources microplastics are released in the first few washes. Fast fashion is a particular problem because these garments account for a high number of first washes

5; Primary microplastics; Secondary microplastics; 14; synthetic textiles; majority

• Cargo Ship Accidents & Ocean Current Mapping

  • _____: goods accidentally lost from ships at sea

  • ______: materials intentionally discarded from ships at sea

  • Tracking flotsam allowed oceanographers to map the speed and trajectory of _____ _____

  • 1990: 61,000 Nike shoes, each with a unique serial number, "The Great Shoe Spill of 1990"

  • 1992: 29,000 plastic bathtub ducks & other toys

  • 1994: 34,000 ice hockey gloves

Flotsam; Jetsam; ocean currents

• Downwelling & Upwelling Along Coastlines

  • Upwelling and downwelling occur at ______ when water is deflected due to _______ ______

  • When water is deflected toward a coastline, _______ occurs

  • When water is deflected away from a coastline, ______ occurs

  • It's not just water that is transported - nutrients, oxygen, salt, and contamination move with the water

coastlines; Ekman transport; downwelling; upwelling

• Coastal Upwelling

  • _______ brings cold, nutrient-rich water to the surface when Ekman transport creates a water deficit

    • Areas where upwelling occurs often have _____ biological productivity

Upwelling; high

• Upwelling and Biological Productivity

  • _______/Microscopic Algae: base of the marine food web

    • Flourish when ______ nutrients are present

  • Coastal upwelling brings nutrients from _______ waters to the surface, making them accessible to _______ producers

Phytoplankton; abundant; deeper; primary

• Water _____ is a function of temperature and salinity

• Denser (colder, saltier) water _____

• _____ dense (warmer, fresher) water is buoyant and rises

• The rising and sinking of water due to density creates a global flow pattern called ______ ______

  • Thermo = ______

  • Haline = _____

• This global conveyor belt of ocean water takes about ______ years to complete a cycle

density; sinks; Less; thermohaline circulation; temperature; salt; 1,000

• Water Masses & Deep Water Formation

  • _____ _____: a volume of seawater that has a distinct density due to its particular salinity and temperature

    • Properties of a water mass don't change easily once they move away from the ______

    • Water masses don't _____ well because of these distinct densities and properties

  • In some areas of the globe, conditions at the surface can lead to water becoming ______, which can cause water masses to sink

Water mass; surface; mix; denser

• Atlantic Meridional Overturning Circulation (______): refers to the part of thermohaline circulation that operates within the Atlantic Ocean basin

  • Research indicates that AMOC is _____ due to climate change, which includes warming oceans, increased rainfall, and melting sea ice

  • AMOC may have slowed up to ____ since 1950

  • AMOC has totally ______ (collapsed) in the past, for example during ice ages

AMOC; slowing; 15%; stopped

• _____ _____ (T-S diagrams): used to identify water masses

  • T-S diagrams have curved lines of equal _____

  • 5 major water masses in the Atlantic Ocean:

    1. North Atlantic Central Surface Water (_______)

    2. Mediterranean Intermediate Water (_____)

    3. Antarctic Intermediate Water (______)

    4. North Atlantic Deep Water (______)

    5. Antarctic Bottom Water (______)

Temperature-Salinity Diagrams; density; NACSW; MIW; AAIW; NADW; AABW

• ______ _______: flow along contents at the eastern and western edges of ocean basins

  • Eastern/western refers to the location within an ______ ______ (not continental landmass)

  • _____ ______ _____: flow in the western part of an ocean basin, moving warm water to the poles

    • Stronger due to the _______ ______

    • The Gulf Stream is a ______ Boundary Current

  • ______ _______ ____: flow in the eastern part of an ocean basin, moving cold water toward the equator

Boundary Currents; ocean basin; Western boundary currents; Coriolis Effect; Western; Eastern boundary currents

• Comparing Eastern and Western Boundary Currents

  • Western boundary currents tend to:

    • Be ______ than typical surface currents (down to 1,000 m (3,000ft))

      • Deflected by the _______ _______, don't flow onto the shallower continental shelf

      • Move _______, 40 - 120 km (25-75 mi) per day

      • Ex: Gulf Stream, Kuroshio Current, East Australian Current, Brazil Current, Agulhas Current

  • Eastern boundary currents are:

    • Slower

    • Shallower

    • ______

    • Ex: California Current System, Peru-Chile Current, Canary Current, Beguela Current, Leeuwin Current

deeper; continental margin; rapidly; Wider

• Antarctic Circumpolar Current

  • Driven by strong ______ winds

  • Exists because no _____ blocks the flow of water, so a strong current of water encircles Antarctica

  • The ______ _______, between South America and Antarctica, is the roughest patch of ocean on Earth

  • It’s the _______ (190 km (120 mi)) and deepest (down to 4 km (2.5 mi)) surface current

  • Its presence _________ warm water from the Atlantic, Pacific, and Indian Oceans from mixing with the cold water around Antarctica. This helps to maintain Antarctica's cold climate and therefore, its ice sheets

  • Cold water ________ from the Antarctica's continental shelf to form Antarctic Bottom Water (AABW)

    • This powers _______ _______

westerly; land; Drake Passage; widest; prevents; descends; thermohaline circulation