Term
|
Definition
|
|
Term
|
Definition
| they influence weather and climate, distribute nutrients, and scatter organisms |
|
|
Term
|
Definition
| wind driven movements of water at or near the ocean's surface |
|
|
Term
|
Definition
| slow, deep currents that affect the vast bulk of seawater beneath the pycnocline; dependent on density (i.e., temperature and salinity) |
|
|
Term
| Info about surface currents |
|
Definition
| Water flowing horizontally in the uppermost 400 meters of the ocean's surface; mainly driven by wind friction. 10% of the water in the ocean is involved in these. Most of them occur above the pycnocline. |
|
|
Term
| Wind patterns drive surface currents |
|
Definition
| Surface winds form global patters within the latitude bands. Waves transfer this wind energy to water by friction... creating surface currents. The prime "movers" are the Trade Winds and the Westerlies. |
|
|
Term
|
Definition
(gyros, "a circle")
a circuit of mid-latitude surface currents around the periphery of an ocean basin |
|
|
Term
The oceans surface circulates clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere, forming gyres because of:
|
|
Definition
| surface winds, sun's heat, gravity, Cariolis Effect |
|
|
Term
| Gravity and Coriolis Forces |
|
Definition
| Water "piles up" in the direction the wind is blowing; pressure increases onthe "piled up" side; the force of gravity acts against the pressure gradient. the Coriolis effect causes surface currents to flow to the right of the wind direction in the Northern Hemisphere and to the left of the wind direction in the Southern Hemisphere. Where the flow is blocked by continents or basin topography, currents turn Clockwise in the Northern Hemisphere or counterclockwise in the Southern Hemisphere. |
|
|
Term
| Surface currents flow at a velocity of... |
|
Definition
| less than 3% of the speed of the driving wind |
|
|
Term
| the topmost layer of ocean water flows at... |
|
Definition
| About 45 degrees to the right (Northern Hemisphere) of the wind direction |
|
|
Term
|
Definition
| Water in the next layer down cannot "feel" the wind at the surface. Underlying water layers move at an angle to the right (N. Hemisphere) of the underlying water until a deth of about 100 meters. The result is called... |
|
|
Term
| What about the water in the next layer down? |
|
Definition
| Each lower layer moves more slowly due to frictional losses. At some depth (friction depth) water will flow in the opposite direction of the surface current. Net motion of the water is known as Ekman transport. |
|
|
Term
|
Definition
|
|
Term
| Ekman transport, pressure gradient |
|
Definition
| Some of the Atlantic water has turned (______), forming a hill (_____). |
|
|
Term
|
Definition
(Geos, "Earth"; strophe, "turning")
gyres in balance between the pressure gradient and the Coriolis effect |
|
|
Term
| There are 6 great circuits in the ocean; 5 are geostrophic gyres |
|
Definition
1. North Atlantic Gyre
2. South Atlantic Gyre
3. North Pacific Gyre
4. South Pacific Gyre
5. Indian Ocean Gyre
6. West Wind Drift (Antarctic Circumpolar Current) - is technically not a gyre |
|
|
Term
| Geostrophic currents (Boundary currents) are classified by their position within a gyre as: |
|
Definition
1. Western Boundary Currents
2. Eastern Boundary Currents
3. Transverse Currents |
|
|
Term
| The volume of water transported in ocean currents |
|
Definition
Measured in the sverdrup (sv)
1 sv = 1 million m3 per second |
|
|
Term
| Western boundary currents |
|
Definition
narrow, deep, fast currents found at the western boundaries of ocean basins (eastern coasts of continents)
- the Gulf stream, the Japan Current, the Brazil current, the Agulhas current, the Eastern Australian current |
|
|
Term
|
Definition
the largest of the western boundary currents
- flow of more than 55 sv, about 300 times the flow of the Amazon River |
|
|
Term
| Eastern boundary currents |
|
Definition
cold, shallow, and broad, and their boundaries are found at the eastern boundaries of ocean basins (western coasts of continents)
- the Canary current, the Benguela current, the California current, the West Australian current, the Peru Current |
|
|
Term
|
Definition
| currents that flow from east to west and west to east; link western and eastern boundary currents. Westerly winds (weaker winds) drive easward transverse currents. Trade winds (stronger winds) drive the westward transverse currents. The Pacific's greater expanse of water at the equator and strong trade winds.. More powerful westward-flowing equatorial currents, height different of about 1 meter between wester and eastern Pacific. |
|
|
Term
| West Wind Drift (Antarctic Circumpolar Current) |
|
Definition
| the greatest of all ocean currents. intense westerly winds. unimpeded flow (no continents). flow of more than 100 sv (100 million meters3 per second) |
|
|
Term
| Western boundary currents vs Eastern boundary currents |
|
Definition
| Western boundary currents are well defined, meaning edges are clearly visible. Eddy is a circular movement of water usually formed due to friction with adjacent waters/currents. Currents meander as they flow poleward, trapping cold or warm water in their centers which separate from the main flow. Eastern boundary currents are not well defined, eddies do not form. |
|
|
Term
|
Definition
| a circular movement of water usually formed due to friction with adjacent waters/currents |
|
|
Term
| Why should western boundary currents be concentrated and eastern boundary currents be diffused? |
|
Definition
westward intensification.
The strength of the Coriolis effect increases as water moves farther from the equator. Eastward moving water is turned sooner and more strongly toward the equator than westward moving water at the equator is turned toward the pole. |
|
|
Term
| wind-induced vertical circulation |
|
Definition
| vertical movment induced by wind-driven horizontal movement of water |
|
|
Term
|
Definition
| the upward motion of water. This motion brings cold, nutrient rich water towards the surface |
|
|
Term
|
Definition
| downward motion of water. It supplies the deeper ocean with dissolved gases. |
|
|
Term
|
Definition
| water moving in currents on either side of the equator is deflected slightly poleward and replaced by deeper water (due to differences in Coriolis Effect at equator) |
|
|
Term
|
Definition
| Wind blowing parallel to shore, moves water. Coriolis effect deflects water to right (N. Hemisphere) or left (S. Hemisphere). Ekman transport is offshore. Surface water is replaced by water rising along the shore. High biological productivity occurs. Affects climate - cold water rising from deep. |
|
|
Term
|
Definition
| Water driven towards the coastline will be forced downward, returning seaward along the continental shelf. Supplies deep ocean with dissolved gases and nutrients. Assists in distribution of living organisms. No direct affect on climate or productivity. |
|
|
Term
|
Definition
| normally the air and surface water flow westward, the thermocline rises, and upwelling of cold water occurs along the west coast of Central and South America |
|
|
Term
|
Definition
| the Southern Oscillation develops, the trade winds diminish and then reverse, leading to an eastward movement of warm water along the equator surface waters of the central and eastern Pacific become warmer, and storms over land may increase. Occurs roughly every 3-8 years. |
|
|
Term
|
Definition
| the vigorous reversal of El Nino leading to strong currents, powerful upwelling, and chilly and stormy conditions along the South American coast |
|
|
Term
|
Definition
| Slow, deep currents (below pycnocline) that affect the vast bulk of seawater; dependent on density (i.e., temperature and salinity). ocean is density stratified, with the densest water at the bottom. Five common water masses: surface water, central water, intermediate water, deep water, bottom water |
|
|
Term
|
Definition
| the densest water in the world. majority produced near Antarctic coast south of South America during winter. Salt is concentrated in pockets between crystals of pure water and then squeezed out of ice as brine. Very cold, very salty water. It sinks because of its extreme density. Migrates north along seafloor. May take 1000 years to reach equator. |
|
|
Term
| North Atlantic Deep Water |
|
Definition
| Deep water is also formed in the northern polar ocean, but must escape through deep channels. Water formed in Arctic flows into the North Atlantic to form North Atlantic deep water. Cold winds from Canda cool water and it sinks. |
|
|
Term
|
Definition
| Relative vertical stratification always determined by density |
|
|
Term
| Water masses may converge, fall, travel across the seabed, and slowly rise |
|
Definition
| Great quantity of dense water sinking at polar ocean basin edges must be offest by equal quantities of water rising. Water rises much more gradually than it sinks. Water sinks in a small portion of the ocean (poles), rises over greater portions of the ocean (temperate/tropic zones) |
|
|
Term
|
Definition
| water masses run into each other and denser water slides underneath less dense water |
|
|
Term
|
Definition
| Carries surface water to the depths and back again. Formation of North Atlantic Deep Water north of Iceland, the water mass flows south through the Atlantic and then flows over (and mixes with) deep water formed near Antartica. These masses circumnavigate Antarctica and then move north into the Indian and Pacific ocean basins. Slow upwelling in all of the ocean returns some of this water to the surface. Water in the conveyor gradually warms and mixes upward to be returned to the North Atlantic by surface circulation. Transports water and heat. |
|
|
Term
|
Definition
| Deep water masses move very slowly relative to surface gyres, however, even at the slow speed Coriolis effect modifies their pattern of flow |
|
|
