chapter 7 oceanography test

deep-water circulation brings dense, cold, oxygen-rich water from the surface to the deep ocean because of.....

greater dissolution of oxygen in colder water than warmer water

circular movement of surface water currents driven by the major wind belts are called....

gyres

in what ocean to monsoons occur?

indian ocean (northeast - winter, southwest - summer)

compare and contrast the direction of the northern and southern hemisphere flows of Ekman transport.

north - clockwise south - counterclockwise

subpolar gyres

rotate opposite the adjacent subtropical gyre. * smaller, fewer than subtropical gyres.

how does a gyre form?

wind belts perhaps

what 2 major forces drive the ekman spiral?

wind direction and coriolis effect

does deep ocean water travel across the equator?

yes, very slowly

under what conditions does strong upwelling occur?

la nina!

compare and contrast the forces that cause the deep and surface currents. 3 forms of evidence of movement on earth?

* energy from the sun drives currents (primarily), but major wind belts really influence direction of surface currents. deep water = also sun-driven, but influenced by density (salinity/temperature) - actually dnt know if this is right

what is a doppler flow meter?

- Indirect method of measuring surface current * transmits low-frequency sound signals through the water. The flow meter measures the shift in frequency between the sound waves emitted and those backscattered by particles in the water to determine current movement.

Discuss the biological impact of upwelling and downwelling on marine ecosystems. Provide examples of marine systems that are impacted by these processes in your answer.

- Upwelling - nutrient-rich water creates high productivity, which establishes the base of the food web and supports incredible numbers of larger marine life such as fish and whales. - Downwelling - associated with much lower productivity, but carries necessary dissolved oxygen to those organisms living on the deep-sea floor.

walker circulation cell

- air pressure across equatorial pacific is higher in east pacific, creating very strong trade winds. - pacific warm pool on western side of ocean. - thermocline pushed deeper on western side, resulting in upwelling off coast of peru.

ekman transport

- average movement of seawater under influence of wind * 90 degrees to right of wind in Northern hemisphere * 90 degrees to left of wind in Southern hemisphere

describe the location of the western boundary and eastern boundary current within a gyre. how is the direction of these currents related to heat distribution of the Earth's oceans?

- eastern boundary current = eastern portion of ocean basin, moves cold water. - western boundary current = western portion of ocean basin, moves warm water.

characteristics of west wind drift (latitude, etc)

- encircles antarctica - flows WEST to EAST at approx. 50 degrees south latitude. - only current that completely circulates earth - transports more water than any other surface current!

characteristics of la nina (cool phase)

- increased pressure difference across equatorial pacific - stronger trade winds - stronger upwelling in east pacific - shallower thermocline - strong upwelling - cooler than normal seawater - high biological productivity

importance of gulf stream

- most studied current - warms coastal states, moderates winters in northern european regions. - moves northward along east coast of US - warm- and cold-core rings maintain unique temperature characteristics, often contain distinct population of marine life. - merges w/ sargasso sea - western boundary current, atlantic ocean

In the southern hemisphere, the direction of Ekman transport is always (to the left or the right of the wind pattern?)

- to the LEFT!! * current speed decreases with increasing depth; each successive layer of water is set in motion at a progressively slower velocity and in a direction progressively to the right of the one above it. at some depth, a layer of water may move in a direction exactly opposite from the wind direction that initiated it!

characteristics of el nino

- walker circulation cell disrupted - high pressure in e. pacific weakens - weaker trade winds - warm pool migrates eastward - thermocline deeper in e. pacific - downwelling - lower biological productivity

3 forms of evidence of movement on earth?

1. dynamic topography maps produced images that show the speed and direction of surface currents. 2. measure deep ocean currents by mapping underwater floats that are carried within deep waters. 3. (from article) nike shoes that were dropped in the middle of the ocean flowed with currents and ended up on beach shores.

what percentage of earth's currents are surface currents?

10% are surface currents (meaning 90% are deep ocean currents).

how are surface ocean currents organized?

Organized into discrete patterns within each ocean basin; grouped into five main groups, the subtropical gyres - i think???

the ocean's deep water is initially formed at the ________ and in _________ regions.

Surface, subpolar

pycnocline

a zone in which density increases with increasing depth. 18% of all ocean water - boundary between surface & deep layers

describe the monsoon wind patterns during winter months

air over the Asian mainland rapidly cools, creating high atmospheric pressure, which causes the wind to blow from southwest Asia off the continent and out over the ocean.

describe worldwide effects of el nino

alter atmospheric jet stream and produce unusual weather in most parts of the globe. marine life is impacted, forest fires, droughts, and tropical storms.

do deep ocean currents move cold, dense water away from the poles or towards the poles?

away from the poles

northern/southern boundary currents

between 30-60 degrees latitude. winds direct ocean surface water in easterly direction across ocean basin. in northern hemisphere, called NORTHERN BOUNDARY CURRENTS, in southern hemisphere, called SOUTHERN BOUNDARY CURRENTS.

describe upwelling in terms of the causes and effects

cause: vertical movement of cold, deep, nutrient-rich water. effect: high productivity (nutrient-rich), establishes the base of the food web and, in turn, supports incredible numbers of larger marine life.

subtropical gyres in northern hemisphere spin which way? what abt southern hemisphere?

clockwise, counterclockwise.

do Western boundary currents such as the Gulf Stream transport warm or cold water from the tropics towards higher latitudes? Explain your answer.

come from equatorial regions, where water temperature are warm, so they carry warm water to high latitudes.

how does deep ocean water become enriched in oxygen?

deep ocean water can be enriched in oxygen when it is mixed with surface water.

thermohaline flow

describes deep ocean current movement; temperature and salinity. describes changes in seawater density, which creates deep-ocean current movement.

ekman spiral

describes speed and direction of flow of surface water at various depths. - ekman's model assumes that a uniform column of water is set in motion by wind blowing across its surface. - because of coriolis effect, the immediate surface water moves in a direction of 45 degrees to the right of the wind. - as surface layer moves, other layers beneath it are set in motion, thus passing the energy of the wind down through the water column. *each layer moving downward -- water is colder, denser, slower, and moving at less of an angle. water moving slower at the bottom than it is at the top.

measuring surface currents? what 2 types of methods

direct & indirect. - direct: floating device, fixed current meter - indirect: pressure gradient, radar altimeters, doppler flow meter

what force drives Thermohaline circulation?

driven by density (temp./salinity differences)

deep water currents

driven primarily by DENSITY/CONVECTION CELLS and modified by TEMPERATURE AND SALINITY. * driven by diff. in density caused by diff. in temp and salinity. move vertically OR horizontally.

surface currents

driven primarily by WIND BELTS and modified by LAND MASSES / CORIOLIS EFFECT. * driven by wind, move horizontally.

what conditions are caused by Western intensification?

eastern-flowing high-latitude water turns toward the equator more strongly than westward-flowing water turns toward higher latitudes. causes a wide, slow, shallow flow of water toward the equator across most of each subtropical gyre. (not sure)

which pattern of oscillation is created by the relationship between sea surface temperature and changing atmospheric pressure.....El Nino or La Nina?

el nino

measuring deep currents?

floating devices, chemical tracers, temperature/salinity, Argo.

briefly describe the effects of severe El Niño events.

floods, coral reef damage, forest fires, tropical storms, droughts, coastal erosion, marine and bird life is impacted

geostrophic current?

flows in a circular path around the central "hill" of gyre. balances coriolis effect and gravitational forces. friction generates geostrophic flow (as well as temperature, density of salinity, gravity). ** BALANCES CORIOLIS EFFECT AND GRAVITATIONAL FORCES. FRICTION, TEMPERATURE, DENSITY OF SALINITY AND GRAVITY GENERATE GEOSTROPHIC FLOW/CURRENTS!!

the five subtropical gyres exhibit geostrophic flow, related to pressure gradients, friction, and the Coriolis effect. Explain that statement.

geostrophic flow - layers of the ocean pycnocline (shallow, warm, less dense), thermocline (colder, more dense, higher salinity), deep ocean. 5 subtropical gyres are moving because of geostrophic levels, pressure gradients, friction (caused by wind patterns), and the Coriolis effect. * not rly sure

what are subtropical gyres?

large, circular groups of moving water. (1) north atlantic sub. gyre (north america to africa - gulf stream) (2) south atlantic sub. gyre (africa to north america) (3) north pacific sub. gyre (4) south pacific sub. gyre (5) indian ocean sub. gyre

thermocline

middle layer, the zone in which temp. changes rapidly with depth.

what are seasonal pressure systems that develop at lower latitudes over continents, which cause changes in seasonal winds and precipitation patterns?

monsoon???

equatorial countercurrents

narrow, easterly flow of water. occurs counter to and between adjoining equatorial currents.

thermohaline circulation is driven by differences in...

temperature and salinity

where is the densest ocean water found?

the densest ocean water is found at the bottom of antarctica's waters, ANTARCTIC BOTTOM WATER!

what force drives equatorial currents?

trade winds (southeast from southern hemis. northeast in northern hemis.)

equatorial current

travel westward along the equator. form equatorial boundary current of subtropical gyres.

what are the characteristics of Deep ocean water masses in terms of temperatures and salinities?

very cold, high salinity.

first indications of an el nino?

warm water from near australia migrates towards south america, upwelling decreases.

main current of antarctic water?

west wind drift!!

antarctic circumplar current is also known as...

west wind drift. main current in antarctic waters.

difference between western boundary currents and eastern boundary currents?

west: fast, narrow, deep, warm east: slow, wide, shallow, cold

western intensification

western boundary currents intensified in both hemispheres.

upwelling, what causes it, high or low biological productivity???

what it is - the vertical movement of cold, deep, nutrient-rich water to the surface. what causes it - (1) surface waters move away from area on ocean's surface, such as along the equator. divergence of currents along the geographical equator cause upwelling of cold, nutrient rich water. because this type of upwelling is common along the equator (especially in Pacific), it is called *equatorial upwelling* (high productivity). (2) Ekman transport moves surface seawater offshore; cool, nutrient-rich deep water comes up to replace displaced surface water (coastal upwelling - west coast) (3) deep ocean currents reach landmasses and are forced up. (4) can also be caused by offshore winds, seafloor obstruction, coastal geometry change. high or low bio. productivity? high!!!

downwelling, what causes it, high or low biological productivity?

what it is - the vertical movement of surface water to deeper parts of the ocean. what causes it - (1) the water stacks up along the shoreline and has nowhere to go but down, in a process called coastal downwelling. areas where coastal downwelling occurs have low productivity and a lack of marine life. - more simply, ekman transport moves surface seawater toward shore, water piles up and moves downward in water column. high or low bio. productivity??? low!!!

eastern boundary currents

when currents flow back across ocean basin, coriolis effect/continenal barriers turn these currents towards the equator (eastern boundary of ocean basins). Cool water carried to lower latitudes. * canary current

western boundary current

when equatorial currents reach w. portion of ocean basin, they must turn because they cannot cross land. comprise western portion of subtropical gyres/ocean basins. * gulf stream