47 terms

Oceanography Chapter 7 Test


Terms in this set (...)

is the vertical movement of surface water to deeper parts of the ocean.
Describe upwelling and the conditions that produce it
Created by offshore winds, seafloor obstructions, or a sharp bend in a coastline. Upwelling also occurs in high-latitude regions, where there is no pycnoline.
Ekman transport
The net transport of surface water set in motion by wind. Due to the Ekman spiral phenomenon, it is theoretically in a direction 90 degrees to the right and 90 degrees to the left of the wind direction in the Northern Hemisphere and Southern Hemisphere, respectively.
How Are Ocean Surface Currents Organized?
The distribution of cont land and the coriolis effect change the nature and direction of flow of these surface currents
geostrophic current
A current that grows out of Earth's rotation and is the result of a near balance between gravitational force and the Coriolis effect.
Is the vertical movement of cold, deep, nutrients-rich water to the surface
Gulf Stream
The high-intensity western boundary current of the North Atlantic Subtropical Gyre that flows north off the East Coast of the United States
West Wind Drift
The main current in Antarctic water is the Antarctic Circumpolar Current
How do Surface or wind-driven currents move water? In what direction?
westward-flowing, wind-driven surface currents near the equator turn northward on the north side of the equator and southward on the south side. Surface waters are moved away from the equator and replaced by upwelling waters.
What is a Doppler flow meter?
is a volumetric flow meter which requires particulates or bubbles in the flow.
What percentage of the earth's currents are Surface currents?
What causes Surface ocean currents and how do they flow/what direction do they flow?
Surface currents develop from friction between the ocean and the wind that blows across its surface.
The circular movement of surface water currents driven by the major wind belts are called
Do Western boundary currents such as the Gulf Stream transport warm or cold water from the tropics towards higher latitudes? Explain your answer.
Warm Water top of the hill water displaced toward west due to Earth's Rotation
Compare and contrast the depth, speed, and width of the eastern and western boundary currents
What is the main current in Antarctic waters? What other name is it known as?
The main current in the Antarctic currents is the Antarctic Circumpolar Current also known as the West Wind Drift.
What is the latitude of the West Wind Drift? What ocean does it occur in and what are the characteristics of this current?
This current encircles Antarctica and flows from west to east at approximately 50 degrees south latitude but varies between 40 and 65 degrees south latitude. Antarctic currents
What are seasonal pressure systems that develop at lower latitudes over continents, which cause changes in seasonal winds and precipitation patterns?
What force drives Thermohaline circulation?
The density variations that causes deep ocean circulation are caused by differences in temperature and salinity, deep-ocean circulation
Discuss the origin and characteristics of deep-ocean currents
Most water involved in deep-ocean currentss originates in high latitudes at the surface
Do Deep ocean currents move cold, dense water away from the poles or towards the poles?
Away from poles
How does deep ocean water become enriched in oxygen?
Cold water can dissolve more oxygen than warm water. Thus deep water circulation brings dense, cold, oxygen-enriched water from the surface to the deep ocean. During this time in the deep ocean, deep water becomes enriched in nutrients as well, due to decomposition of dead organisms and the lack of organisms using nutrients there.
Does Deep ocean water travel across the equator?
No it does not travel across the equator
What are the characteristics of Deep ocean water masses in terms of temperatures and salinities?
Surface water becomes cold and salinity increases as sea ice forms.
Where is the densest ocean water found?
Rapid water freezing produces very cold, high-density water that sinks down the contintal slope of Antarctitca and becomes Antarctic Bottim Water the densest water in the open ocean
Deep ocean currents are driven primarily by ________ and modified by ________.
density differences; differences in salinity and temperature
Surface ocean currents are driven primarily by ________ and modified by ________.
wind; the Coriolis effect and land
What is a gyre? How does it form?
The large circular-moving loops of water that are driven by the major wind belts of the world.
Compare an eastern boundary current in a gyre to a western boundary current?
warmer water
narrower current
deeper current
increased current velocity
broad and slow
What two major forces drive the Ekman spiral?
the wind and the Coriolis effet
Which type of current flow moves in a circular path around a subtropical convergence, reflecting Ekman transport, gravity, and the Coriolis effect?
Geostrophic circulation
In the southern hemisphere, the direction of Ekman transport is always (to the left or the right of the wind pattern?) Explain why!
ideal condittions rarely exist in the ocean, so the actual movement of surface currents deviates slightly from the angles surface currents move at an angle somewhat less than 45 degrees from the direction from the direction of the wind and Ekman transports in the open ocean is typically about 70 defrees from the wind direction
What two forces drive Geostrophic circulation within a gyre?
Subtropical Convergence and the Coriolis Effect
What conditions are caused by Western intensification?
1. equatorial countercurrents.
2. a steeper slope of surface water in the western section of the gyre as compare to the eastern section of the gyre.
3. very swift western boundary currents.
4. the center of the gyre to be shift to the west.
Describe upwelling in terms of the causes and effects:
Hoist chilled water to the surface this cold water rich in nutrients creates high productivity which establishes the base of the food web and in turn supports incredible numbers of larger marine life like fish and whales.
Under what conditions does strong upwelling occur?
Where there is no pycnocline
Describe the monsoon wind patterns during winter months
During this season ther is little percipitation because the air associatated with high pressure over land is so dry.
Which pattern of oscillation is created by the relationship between sea surface temperature and changing atmospheric pressure.....El Nino or La Nina?
El Nino
Thermohaline circulation is driven by differences in
water density which is controlled by temperature and salinity
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
Briefly describe the different ways that ocean currents are measured.
Devices called Recording Current Meters can be used. They are basically small probes, sunk into the ocean that measure the speed and other characteristics of the water as it moves by. There are also special buoys that do the same thing.
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?
A large amount of water is driven westward due to the north and south equatorial currents. Due to the coriolis effect, it piles up on the western margins, making it up to 2 meters higher up than the water on the eastern side. Then, under the force of gravity, it flows eastward and counter to the adjoining continental currents. A large counter current exists in the Pacific Ocean, due to the large equatorial space in the Pacific Ocean, as well as the fact that continual influx of water creates a dome trapped between Australia and Asia. There is not so much of a equatorial countercurrent in the Atlantic, due to the bounding nature of the continents. In the Indian ocean, the existence of an equatorial current is strongly influenced by monsoons.
Briefly describe the effects of severe El Niño events.
California may experience warmer ocean temperatures after a severe El Niño. The warm water, centered on Galapagos, transfers its heat out. In severe El Niños the waters of California may warm several degrees above normal (more pronounced in Southern California than in Northern California). This warming will change the environment for California's marine life. Species that can not tolerate this warming may die (or move north to cooler water). If the warmth creates an abnormal thermocline it will lock nutrients out of the surface waters and marine plants may be affected. Tropical marine forms (from Mexico) may migrate north in the warmer waters (like red crabs) and change the California marine environment. In general, when the water returns to its normal temperature these tropical species disappear.
Discuss and compare the forces that are responsible for creating surface and thermohaline circulation in the oceans. Include in your answer the ultimate source of energy that drives both circulation system
Mass flows of water, or currents, are essential to understanding how heat energy moves between the Earth's water bodies, land masses, and atmosphere. The ocean covers 71 percent of the planet and holds 97 percent of its water, making the ocean a key factor in the storage and transfer of heat energy across the globe. The movement of this heat through local and global ocean currents affects the regulation of local weather conditions and temperature extremes, stabilization of global climate patterns, cycling of gases, and delivery of nutrients and larvae to marine ecosystems.
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.
Currents play a huge role in marine productivity, through a process called upwelling. Sea life is concentrated in the sunlit waters near the surface, but most organic matter is far below, in deep waters and on the seafloor. When currents upwell, or flow up to the surface from beneath, they sweep vital nutrients back to where they're needed most. Nowhere is the link between ocean circulation and productivity more evident than around Antarctica. There, strong currents pump nitrogen and phosphate up from the deep sea to fuel vast blooms of algae and other plants. These plankton are eaten by swarms of shrimp-like crustaceans called krill. Because of upwelling nutrients, krill are abundant enough to feed the largest animals on earth, baleen whales, as well as myriad penguins, seals, and seabirds.
Describe the El Niño Southern Oscillation. What global environmental effects characterize an El Niño event? What global environmental effects characterize a La Niña event?
El Niño and La Niña are opposite phases of what is known as the El Niño-Southern Oscillation (ENSO) cycle. The ENSO cycle is a scientific term that describes the fluctuations in temperature between the ocean and atmosphere in the east-central Equatorial Pacific (approximately between the International Date Line and 120 degrees West). La Niña is sometimes referred to as the cold phase of ENSO and El Niño as the warm phase of ENSO. These deviations from normal surface temperatures can have large-scale impacts not only on ocean processes, but also on global weather and climate. El Niño and La Niña episodes typically last nine to 12 months, but some prolonged events may last for years. While their frequency can be quite irregular, El Niño and La Niña events occur on average every two to seven years. Typically, El Niño occurs more frequently than La Niña.
Describe the circulation of deep ocean water.
Ocean water is constantly moving. Thermohaline circulation is another thing to think about when discussing deep ocean currents. It is also known as "The Great Ocean Conveyor" because it works like a conveyor belt. It is driven by heat and salinity of the sea water which is where the term thermohaline comes from. Temperature and salinity make up the density of the water. There are different densities that occur in the ocean waters of the world and this is what causes the currents. Cold and salty water from the northern Pacific and northern Atlantic return warmer and less salty water. The North Atlantic deep water is what causes the thermohaline circulation.