Oceanography final exam study guide PDF

Preview

Summary

study guide for the cumulative final for Prof Woodruff...

Description

SECTION 1 1.

what percentage of our planet is covered with water? a. 71% 2. Know what the following are: Geosphere, Biosphere, Atmosphere, Hydrosphere and Cryosphere a. Geosphere: earth surface and interior b. Biosphere: life on land/sea c. Atmosphere: weather and climate d. Hydrosphere: water and ocean (on land or on subsurface) e. Cryosphere: mountain, glaciers, polar ice caps

1. How can you determine the circumference of the Earth? a. Trigonometry: uses known distances and angle of sun to estimate circumference of earth b. 360/7.2=x/500 2. What is Latitude and Longitude? a. Latitude = north and south (90degrees) b. Longitude: east and west (180 degrees) 2. What are the units for Latitude and Longitude and how do you convert between minutes and seconds and decimal degrees? a. Latitude: 1 degree = 60min =3600 sec b. Longitude: 15 degree/hour--> (local time-GMT) * 15d/hour 2. How can you calculate your Latitude from the North Star? a. Directly north = 90 degrees N b. Angle of star shows location 2. How can you calculate your Longitude with time? a. Local - GMT *15d/h 2. What does GPS stand for and how does it work? a. Global position system

b.

2.

2. 2.

1. 1. 2.

2.

Uses intersection of 4 satellites to find exact location by knowing distances from places What is bathymetry and topography (what is an isobaths)? a. Bathymetry: measures water depth b. Topography: measures land elevation c. Isobaths: lines on map that show equal depths What is Two Way Travel Time (TWT)? a. Sounds travels there and back, must divide by 2 to get depth What is the approximate speed of sound in water (how does this compare to the speed of sound in air and through a solid such as steel)? a. 1482 m/s--> 1500 m/s b. Faster than air, slower than steel (closeness of particle for vibrations) How is depth calculated using the speed of sound in water and TWT? a. D = (v*T)/2 --> velocity / time What is the Exclusive Economic Zone and how far does it extend offshore? a. Underwater boundaries of a country--> 200 nautical miles What is density, how is it calculated, and what are its units? a. Density = M/V b. g/cm^3 What does the interior of the Earth look like?

1. How does the density of material change as you progress from the Earth’s core to the surface? a. Decrease b. Core--> crust 2. Why do continents have a higher elevation when compared to ocean basins a. Thicker and less dense than oceanic crust 2. Is continental or oceanic crust older and why? a. Continental--> Oceanic crust is more recently made by spreading zones 2. What kind of rocks make up oceanic crust? Continental crust? a. Oceanic: basalt b. Continental: granite 2. What is isostatic equilibrium? a. Lithosphere float on more dense rock--> depth depends on weight of rock 2. What is glacial isostatic rebound (i.e. why is land rising in Canada and sinking along the U.S. east coast)? a. Glaciers on land depressed the crust and then ice melts--> land rebounds and rises b. Water decreases if land rises 2. What is a convergent plate boundary and what are the 3 different types? a. Subduction of 2 plates a. Ocean to ocean--> island arcs b. Ocean-continent--> volcanoes, deep earthquakes, trenches c. Continent-continent--> high mountains, shallow earthquakes 2. What different type of landforms do you find at each of these 3 convergent boundaries? a. Island arcs b. Volcanic mountains c. High mountain ranges 2. What are spreading centers and where are they located on earth? a. Transformation faults where magma rises and creates new crust a. Pacific and Atlantic ridges 2. How can you calculate the half-spreading and full spreading rates at mid-oceanic ridges? a. Half-life: distance/millions of years b. Full life: 2 (distance/millions of years) 2. Where is the oldest and youngest ocean crust found? Why? a. Oldest Atlantic b. Newest @ spreading centers 2. How do the spreading rates compare between the East Pacific Rise and the Mid-Atlantic Ridge? a. Pacific is faster than the Atlantic 2. Be able to identify the number of tectonic plates in a given cross-section

1. What is a “hot spot”? Give two U.S. examples discussed in lecture. a. Weak location in earth's crust where magma rises through the crust as over moves over it a. Yellow stone and Hawaii 2. What is a transform fault and where is one located in the U.S.? a. Plate that slides and shifts past each other b. San Andres’s fault 2. What is an accretionary prism and where is it found? a. Zone in trench where sediments are squeezed due to convergence of 2 plates b. Offshore japan

SECTION 2 Water and Salt 1. What are the 5 unique properties of water? a. Unique response of density to temperature--> liquid water increases in density as it cools until it turns into ice (less dense than liquid water) b. High boiling and freezing points c. High heat capacity d. High latent heat of vaporization (amount of heat required to change water into steam) and a high latent heat of fusion (heat needed to melt ice) e. One of the best solvents on earth0 2. What is latent heat? What is sensible heat? a. Latent heat: heat needed to change water from one phase to another, occurs w/out a change in temperature b/c heat gained/lost is used to build or break hydrogen bonds b. Sensible heat: increase in the vibrations of the molecules increases with temperature (normal heat) 2. What is a calorie? a. 1 Cal = amount of energy needed to raise 1 g of water 1 degrees C 2. How many calories does it take to vaporize 1 gram of water? How many calories does it take to raise the temperature of 1 gram of water 100 degrees C? a. 540 Cal/gram

b. 100 Cal of heat 2. What is the hydrologic cycle? How is heat removed from the ocean? How is heat released into the atmosphere? a. Hydrologic cycle is the cycle of water as it goes through its 3 state changes b. Heat is removed from the ocean through evaporation c. Evaporated water is condensed and then releases its heat in the atmosphere 2. What are the sic most common ions in water? Which of these elements are derived from chemical weathering of rock? Which are from volcanic emissions? Which are from hydrothermal activity? Which are from accretionary prisms? a. Chloride b. Sodium c. Sulfate d. Magnesium e. Calcium f. Potassium 2. How are salts removed from seawater (sinks for salts)? a. Biological activity--> skeletons and recycling of nutrients b. Burial in sediments--> clays, biogenic ooze, halite c. Hydrothermal activity on the seafloor--> iconic exchange by spreading center, low oxygen zones of continental margins d. Subduction--> recycling of crust and sediments 2. What is the average salinity of ocean water? Where is the salinity greater than this in the ocean and why? What are the units commonly used to quantify salinity and how is it calculated? Where is the salinity of the ocean less than this and why? a. Average salinity of the ocean is 35 0/00 b. Dead sea c. Parts per thousand (0/00) --> grams of dissolved solids per kilogram of water Stratification, Solar Heating, and Seasons 1. What are the reason for the seasons? a. Tilt of the earth--> 23.5 degrees 2. What is aphelion? What is perihelion? a. Aphelion = time earth is further to the sun b. Parhelion = time earth is closest to the sun 2. What is a solstice? When does it occur during the year? a. Winter solstice (December 21) --> most intense radiation center is at 23.5 degrees S b. Summer solstice (June 21) --> most intense rays of sunshine hit 23.5 degrees N 2. What is the equinox? When does it occur during the year? a. Sun directly over the equator b. March 21, September 21 2. What is the solar footprint and how does it vary from equator to pole? How does this affect the net gain/loss in solar radiation from these two locations? a. Solar footprint is the amount of radiation from the sun spread out through the different latitudes

2.

2.

2.

2.

2.

2.

2.

2.

2.

b. Higher latitudes have a larger solar footprint b/c the solar energy is dispersed across a wider area--> low angle of incidence (net gain) c. Lower latitudes have a small solar footprint because the solar energy is focused on a smaller location due to the earth's speherical shape (net loss) Why does low pressure dominate in the tropics and high pressure the poles? a. Low pressure dominates tropics because warmer climate evaporates ocean water and creates light humid air b. High pressure dominates the poles because the colder temperature creates dense heavy air How do air and water masses move in relation to areas of low and high pressure? a. Warm air and water rise in low pressure areas b. Air and water cool and then fall in high pressures The equator has a net gain of energy for the sun and the poles a net loss due to more radiation to space. Given this fact, why is the equator not continually heating up and the poles not getting colder and colder? a. Ocean and water circulations b. Warm water/energy moves from equators to poles--> warms the poles c. Cold water/energy moves from pole to equator--> cools the equator Based on the uneven heating of the earth, predict the temperature profiles of the water column for the low latitudes, mid latitudes, and high latitudes? a. Low latitudes: heavy precipitation, warmer climate, not much seasonal change b. Mid-Latitudes: strong seasonality, warm to cool surface waters with low salinity c. High-Latitudes: low precipitation, icy conditions What is the mixed layer? a. Layer on ocean above the permanent thermocline b. Depth depends on the mixing of warmed surface water and storms/waves/currents What is the thermocline? What is the difference between the permanent and seasonal thermocline? a. Permanent thermocline: interval through which temperature decreases as water depth increases b. Seasonal thermocline: summer heating creates a stepper temperature gradient than in winter In temperate waters, how does the thermocline vary during the summer and winter and why? a. Varys depending on temperature b. Seasonal thermocline decreases in the summer c. Increases in the winter How does temperature depth-profiles vary from equator to poles and why? a. Poles: no seasonal/permanent thermocline, very cold waters throughout b. Middle: seasonal thermocline that produces warm surface waters in summer with a pycnocline/permanent thermocline, very cold deep waters c. Low: warm surface waters, permanent thermocline/pycnocline, very cold deep waters How does seawater density very in relation and temperature and salinity?

a. Thermal barrier can be a density barrier b. Seawater density increases with depth 2. What is sigma t and how is it calculated? a. Relationship between density and depth b. (desnity-1.000g/cm3) * 1000 Coriolis and Prevailing Winds 1. Is a person in Florida or Alaska moving faster? Why? a. Florida is moving faster b. Closer to equator which moves about 1600 km/h due to shape of earth 1. How does the earth rotate when viewed from the North pole? How does it rotate when viewed from the South Pole? a. North Pole: counterclockwise (right) b. South Pole: Clockwise (left) 2. If you were in Boston and wanted to fly to Tampa, how would you aim your plane and why? a. Aim it more to the right so when the earth spins, it will be in line 2. How would you direct your plane flying from Tampa to Boston? a. Aim it to the right so when the earth spins, it will be in line 2. What prevailing winds are at what a latitude? a. Polar front: polar easterlies (blow to the SW/NW) b. Forties: Westerlies (blow to NE/SE) c. Subtropical High: horse latitudes (no wind--> dry and hot air) d. Equator (ITCZ, Doldrums): Trade winds (blow to NW/SW) 2. How do the different latitudes change ocean temperature and salinity? a. Different latitudes have different temperatures b. Dense water sinks and helps drive circulation Weather and Climate 1. What is the difference between weather and climate? a. Weather: day-day change in atmosphere through the coming/going of pressure systems b. Climate: weather/temperature patterns accumulated through the years 1. Which way do cyclones rotate in the Northern Hemisphere and why? a. Counter-clockwise (right)--> Coriolis effect 2. What is the difference between hurricanes, typhoons, and cyclones? a. Nothing--> location of ocean basin 2. Why are there no hurricanes at the equator? a. No high-pressure systems to form storm 2. What are monsoons and how are they like onshore/offshore breezes? a. Monsoons are seasonal changes in the prevailing winds b. Caused by the migration of the ITCZ--> lots of rain c. Temperature contrasts between land and sea like breezes 2. How are seasonal changes in the location of the ITCZ linked to tropical monsoons?

2.

2.

2. 2.

a. Migration of ITCZ changes the temperature and pattern of winds, which heats up the ocean and stops the wind from blowing What is the Western Pacific Warm Pool and what does it cause? a. Strong trade winds blow warm water offshore Japan and Asia b. Typhoons What are the changing wind patterns an its impacts during El Nino events? a. Trade winds are weakened/reversed b. Warm water to blow in opposite direction towards Peru--> kills fish c. Dyer conditions in Indonesia and Australia How does El Nino impact fisheries in Peru and why? a. Thermocline is increased and the nutrient-rich water is pushed west, killing the fish What is La Nina? a. The opposite of El-Nino--> stronger conditions of the normal climate

SECTION 3 Lecture 9: Wind Driven Ocean Circulation (132-135) 1. What is the Ekman Spiral and Ekman transport? (lecture notes and p. 138) a. Decrease in current speed with the Coriolis deflection, an increase of depth b. Spiral of water 2. How are surface and net currents directed in relation to the direction of prevailing winds in both the Northern and Southern Hemispheres? a. Surface currents = 45 degrees b. Net currents = 90 degrees c. Opposing/intersecting directions 2. What latitudes are generally associated with the convergence (pile-up) and divergence (moving apart) of water and why? a. Convergence = subtropics--> Coriolis effect b. Divergence= 0, 30, 60 --> pushed by trade winds 2. How do these areas of convergence and divergence relate to regions of upwelling and downwelling? a. Downwelling = sinking of cold, dense water in high latitudes a. Convergence b. Upwelling = rising of water a. Displacement of surface waters b. Costal upwelling and oceanic divergence 2. What is an ocean gyre and where are the 5 primary ocean gyres located on earth? a. Large horizontal wind-driven current systems that circulate around domes and depressions on the ocean's surface a. Gulf Stream--> North Atlantic b. Brazil Current--> South Atlantic c. Kuroshio Current--> North Pacific d. EAC--> South Pacific

2.

2.

2.

2.

2.

2.

e. Agulhas Current--> Indian Ocean Which way do currents circulate in gyres in the N. and S. Hemisphere and why? a. North Hemisphere: rotates to the right (clockwise) b. South Hemisphere: rotates to the left (Counter-clockwise) a. Coriolis Effect Are near-surface currents stronger on the eastern or western side of subtropical gyres and why? a. Western side--> transport warm tropical water via Gulf Stream Do eastern or western boundary currents carry warm water from the tropics poleward? Which carry cold water from the poles to the equator a. Western carry warm water from tropics to poles (gulf stream) b. Eastern carry cold water from poles to the equator (canary current) What are the names for the eastern and western boundary currents for the North Atlantic and North Pacific? a. Gulf stream and Canary Current b. Kuroshio Current? What location in an Ocean Gyre does trash generally get trapped and why? a. Great Pacific Garbage Patch--> trash from ocean get moved into middle and sits where nothing moves trash What is the name of the slow-moving water in the middle of the Atlantic? a. Sargasso Sea

Lecture 10: Thermohaline Circulation 1. Density in sigma t units for temp/salinity a. [density-1.000] *1000 2. Be able to identify the following features in Fig. 3.33: a. Thermocline b. Mediterranean water c. Atlantic intermediate water d. North Atlantic deep water e. Antarctic bottom water

1. What is the thermohaline circulation and what are the important seawater properties that drive it? a. Density driven circulation of deep ocean a. Salinity and temperature determine deep water masses b. Linked with wind circulation 2. Where does deep water acquire its physical and chemical characteristics? a. Cold and salty b. Oxygen rich--> retains O2 better 2. Which of the world’s oceans does deep water primarily form today and at what general latitudes (polar or tropical)? a. North Atlantic (polar) b. Antarctic (polar) 2. Why does deep water form in the Atlantic but not the Pacific? a. Atlantic is saltier--> denser 2. Why is ice formation important in the development of Antarctic Deep Water? a. Ice leaves denser and saltier water 2. How is the Mediterranean Intermediate Water formed? a. Excessive evaporation creates warm and salty water--> dense enough to sink and flow out of the Mediterranean and into the Atlantic 2. Where are the oldest waters in the world’s oceans found? a. North Pacific Lecture 11: Deep Water Waves and Shallow Water Waves 1. What is the difference between transverse, longitudinal, and orbital waves? a. Transverse perpendicular b. Longitudinal = same c. Orbital = circle 2. Be able to define and identify the following wave properties: height (H), length (L), wave crest and wave trough

1. Be able to define wave base as well as how to calculate it using wavelength. a. Wave Base = (L/2) 2. What is the criterion for a deep-water wave? a. Deep wave > (L/2) 2. Do particles in deep water waves have any net motion? a. No, particles rotate in a circle finishing where they started. Deep water waves transfer energy NOT mass 2. What are some different ways that ocean waves are created? a. Wind b. Earthquakes c. Gravitational attraction 2. Be able to define wave period (T), as well as know how to calculate it from wave observations (e.g. if 10 wave crests pass by a point in 10 seconds what is T). a. Time it takes for a wave to complete one full cycle 2. Know what wave celerity is as well as how it relates to wavelength and period a. Speed of wave a. C=L/T b. C= 1.25^ (1/2) c. C=1.56T 2. Be able to describe the 3 variables that wind-wave height depends. a. Wind speed b. Fetch =distance c. Duration of wind

2. Be able to calculate wave steepness and know the steepness-breaking criterion for waves a. Steepness = H/L b. S>1/7 (or .14) --> it will break 2. What is a fully developed sea? a. Fully developed sea: max size ocean waves can get a given wind speed blowing over enough fetch a duration 2. For deep-water waves how does wave celerity change with wavelength and period? a. Increases with wavelength b. Decreases with time 2. Be able to define swell and explain why these types of waves can beat out the storm and reach the coast first a. Beyond the "sea" b. Little loss in energy c. More regular in shape d. Dispersion of trains (linger L waves=faster) e. Interference patterns: swell generate in storm 2. What happens to the height, length, speed, period and steepness of a shallow water wave as the water depth decreases? a. Speed decreases b. Height increase c. Length decreases d. Period does not change 2. What is the criterion for a wave to be either a deep or shallow water wave? a. Shallow water: dL/2 2. For a deep-water wave be able to calculate celerity with just the wave period. 3. What is the only ocean property that you need to know to calculate wave speed for a shallow water wave? a. Depth b. C=3.3*[d^ (1/2)] 2. What is the most common cause for large tsunamis? a. Earthquakes associated with the subduction of oceanic crust 2. Why are areas near subduction zones (like Japan) more prone to tsunamis? a. Communities around Pacific rim b/c of oceanic plate action 2. What is uplift and subsidence? a. Uplift: upwards motion of landforms--> increase in elevation b. Subsidence: sudden sinking/gradual downward motion of the earth's ...