University:
Amherst College
Course:
GEOL 105 | Introduction to Oceanography
Academic year:

2022
Views:

312

Pages:

12
Author:

Amira Hester

1. 2. 2. 2. 2. 2. 2. Be able to define wave base as well as how to calculate it using wavelength. a. Wave Base = (L/2) What is the criterion for a deep-water wave? a. Deep wave > (L/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 What are some different ways that ocean waves are created? a. Wind b. Earthquakes c. Gravitational attraction 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 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 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 surface with little/no horizontal motion 2. Why do tsunamis behave as shallow water waves even in the deep ocean? a. Maintains its high speed/energy b. Similar ration between water depth and wavelength is small Lecture 12: Tides 1. Tides along the coast of New England are semi-diurnal. What does this mean? The Gulf of Mexico has diurnal tides. What does this mean? a. Semi diurnal occurs twice daily high and low tides a. 12 hour 25 mins b. Diurnal occurs one high/low tide daily a. 24 hour 50 mins 2. How long is the tidal period in New England and what does this mean with respect to the timing of consecutive high tides? a. about 12 hours and 12 mins? 2. What are the primary causes of lunar tides on Earth? a. Gravitational pull of the moon creates tidal bulges 2. Why is the lunar tide 12 hrs and 25 minutes? a. Takes the moon an extra 50 minutes to "catch up" to one rotation of the earth 2. Why is the Earth’s lunar tide greater than its solar tide? a. Closer to earth than the sun 2. What are spring and neap tides and what causes them? a. Spring tides: higher high /lower low tides every other week a. Caused by full/new moons being in line with the sun b. Neap Tides: lower high/ higher low tides every other week a. Caused by other phases of the moon when not in line with sun b. First and third quarters of the moon 2. How many spring tides and neap tides occur per month? What is the time between a spring tide and the following neap tide? a. 2 spring and 2 neap tides b. About 1 week 2. What is the difference between rotational and progressive tides? a. Professional tide: tidal bulge (wave crest) moves towards down the ocean basin 2. What are the three different types of tidal cycles? a. Semi-diurnal (twice daily tides) b. Diurnal (one daily tides) c. Mixed (one or two times daily) 2. What is tidal resonance and how does it relate to the tides in the Bay of Fundy? a. Tidal resonance: tides are forced into channel and creates the highest tides b. Bay of Fundy SECTION 4 1. Living tissue and saltwater have nearly the same density a. False 2. What is osmosis and osmatic pressure? a. Osmosis: diffusion of water molecules in and out of cells b. Osmotic pressure: salinity gradient from in and out the cell will cause the water molecules to move from an area of low salinity to high salinity 2. Explain why freshwater fish do not drink water but urinate a lot a. Their bodies are areas of high salinity (denser than the water) so they absorb more water than they drink--> pee more 2. Explain why saltwater fish drink a lot of sea water by urinate only a small amount. a. Their bodies are areas of low salinity (less dense than the water) so water leaves their bodies more often, causing them to need to drink more water to stay hydrated 2. Be able to define hypotonic, hypertonic, and isotonic. Which describes conditions for cells in freshwater fish? Which describes conditions for cells in saltwater fish? a. Hypotonic: concentration of solution is greater inside the cell than in it-->dehydrates b. Hypertonic: concentration of solution is greater outside the cell than in it 2. What happen if you drink too much saltwater? What happen if you drink too much fresh water? a. Too much saltwater-->dehydrates cells and you die b. Too much fresh water--> cells explode/too little salt and you die 2. Define stenohaline and give an example of a marine organism that fits this category a. Stenohaline: organisms that can tolerate only a narrow range of salinity b. Coral reefs 2. Define Euryhaline and give an example of a marine organism that fits into this category a. Euryhaline: organisms that can tolerate a wider range of salinity b. Shark 2. What us an anadromous fish? a. Mature in ocean but spawn in fresh water b. Salmon 2. Define eurythermal. What type of environments do eurythermal organisms commonly exists? a. Eurythermal: tolerate a wide range of temperature changes b. Mid-latitudes, seasonality-->Killer whales 2. Define Stenothermal. What types of environments do stenothermal organisms commonly exist? a. Stenothermal: tolerate a narrow range of temperatures b. Low and high latitudes, little temperature change--> coral reefs 2. Why are ecosystems on the tropics more sensitive to environmental changes than midlatitudes and intertidal zones? a. Contain both stenohaline and stenothermal organisms 2. What type of adaptive strategies have plankton developed to help them float near the surface of the ocean? a. Large surface area to volume ratio b. Developed appendages c. Produce oil topo help them float 2. What are the 3 domains of life and what is a representative for each domain? a. Archaea-->thermophiles b. Bacteria-->cyanobacteria c. Eukarya-->humans 2. What are the phyla? 2. 2. 2. 2. a. Porifera (sponges) b. Cnidaria (corals, jellyfish) c. Platyhelminthes (flat worms) d. Nematoda (round worms) e. Annelida (segmented worms) f. Mollusca (mussels, clams, sea slugs, squid) g. Arthropoda (crabs, shrimp, krill) h. Echinodermata (sea stars, sea cucumbers) i. Chordata (tunicates, sea scalps, vertebrae) What is the most common method for classifying marine animals? a. Nutrition a. Autotrophic: organisms that make their own food b. Heterotrophic: survive by consuming other organisms b. Habitat a. Benthic: live on seafloor b. Pelagic: live in water column b. Mobility a. Motile: organisms that can move about i. Plankton (floaters) ii. Nekton (swimmers)--> shark, turtle, flounder iii. Benthos (bottom dwellers) b. Sessile: organisms that have no ability to move; live attached to the seafloor i. Sea sponges, corals How does nautical control its buoyancy? a. Uses an organ call ed the siphuncle to control the volume of water and gasses its intake Types of plankton a. Phytoplankton: microscopic, single-celled phyotosyn4tic algae a. Diatoms, dinoflagellates b. Zooplankton: multicellular animals, microscopic single-celled protists a. Jelly fish, krill, ciliates b. Bacterioplankton: heterotrophic and photosynthetic forms of bacteria a. Cyanobacteria b. Meroplankton: larval stages of some animals a. Clams, crabs, sponges Types of heterotrophic feeding a. Grazers: float in water and feed on microscopic organisms that surround them b. Predators: feed upon smaller animals a. Most animals in ocean are this b. Filer feeders: able to capture strain organism/particles suspended in water column and extract organic material c. Scavengers: eat decaying remains of other creators d. Deposit feeders: animals that crawl on bottom sediments of ocean and extract bits of food 2. Types of Primary productivity a. Photosynthetic a. 6 (CO2) + (H20) + inorganic + solar --> CoH12O6+6(02) b. Photic zone: depth in ocean in which photosynthesis is possible (~20 m in costal water, ~200m in tropical ocean) c. Always enough solar radiation in tropics but nutrients are cutoff from below by strong thermocline b. Chemosynthesis 2. Upwelling of bottom water a. Equatorial upwelling: surface water pushed away or diverged at equator a. Reason sea surface temp is cooler at equator b. Costal upwelling: surface water pushed away from coast a. Upwelling of cold, nutrient-rich water results in higher productivity 2. Why are coastal ecosystems one of the richest habitats? a. Estuaries b. Tidal mud flaps: inter-tidal areas choked with mud, found in estuaries c. Mangrove Swamps: intertidal areas vegetated by mangrove trees, found in tropic/subtropical estuaries d. Salt marshes: tidal mud flaps vegetated by salt-tolerant grasses, found along shorelines and estuaries e. Coral reefs: rigid structure of calcium carbonate built by colonial coral sand calcareous algae that support biologically diverse communities in the photic zone of tropics f. Risky intertidal zone: steep rocky coast without sediment a. Home ton epifaunal organisms b. Intertidal zone: area between highest a donetidines a. Physical factors that effect organisms include: i. Desiccation ii. Turbulence iii. Extreme changes in temp iv. Changes in salinity b. Soft-bottom intertidal zone: soft bottom communities found in areas where sediment has accumulated a. Home to infauna animals 2. Intertidal zone compositions a. Upper intertidal: limpets, liches, algae b. Middle intertidal: barnacle, mussels c. Lower intertidal: kelps, surf grass 1. Corals a. Cannot survive without endosymbiotic zooxanthella--> makes up 98% of coral reefs b. Coral bleaching: higher water tempos make coral expel the zooxanthellae, causing them to turn white c. Fringing reef: formed around shallow water of the tropics/subtropics where there is little sediment input to reduced salinity from river runoff d. Barrier reef: hard, Resita reef framework grows nearly sea level and drops off abruptly to the adjacent sea floor e. Atoll reef: continues upward group of the reef as volcano subsides a. If reef dies, the volcano will continue to subside oat time, producing a flattopped guyot SECTION 5 1. At what depth do waves begin to refract (i.e. at what depths do waves begin to feel the bottom, note this is also the depth when they start transporting sediment)? a. Depth >L/2 2. What is the difference between wave refraction, wave diffraction and wave reflection? a. Refraction: bending of waves as they enter shallow water, go through a channel b. Diffraction: waves radiate outward due to passage through narrow openings, like between islands c. Reflection: waves collide with rigid objects, such as seawall or ships, with little loss of energy 2. How does wave refraction tend to bend waves as they approach shore? 2. 2. 2. 2. 2. 2. 2. 2. 2. a. Wave refraction tends to bend waves so that they are bend towards the shore, parallel to coast!! Be able to identify the areas where wave energy is focused and dispersed along a coastline, as well as the areas of erosion and deposition (for headlands and embayment) a. Focused on headlands--> parts of the coast the extend out further into the sea b. Dispersion--> between the headlands are bays for refracted wave creates embayment’s a. Deposition of sand makes pocket beach Be able to calculate the water depth that waves of a given length will begin to bend or refract towards the coast a. D > L/2 Why do we say that barrier beaches represent an example of a dynamic coastline? a. Beaches are dynamic because they are constantly changing their form and position in response to things like wind, waves and sediment supply. Deltas are another example of a dynamic coastline. What is a headland? Is wave energy focused or dispersed there and does this promote deposition or erosion? a. Headland: part of cost that sticks out, wave energy is focused here and erode the headlands What are embayment’s and pocket beaches? Is wave energy focused or dispersed here and does this promote deposition or erosion? a. deposition a. Pocket Beach: beach formed due to wave dispersion of an embankment b. Coastal Straightening: erosion of headlands and deposition in bays served to straighten coasts over time How does a coastline’s shape typically evolve over time and why? a. Costal straightening: erosion of headlands and deposition in bays serves to straighten coast over time What is swash? a. uprush of water onto beach by wave Be able to define and explain the cause of longshore drift a. Longshore Drift: along coast transport of sand in surf zone due to breaking waves (rivers of sand) b. Movement of sand down the coast Define and provide examples of both hard and soft stabilization? a. Hard stabilization: armoring of coast with rocks and man-made structures to protect the coast from erosion, trap sand, or redirect wave energy a. Sea wall, groins, jetties, breakwaters b. Soft stabilization: replace sand that has been lost from longshore drift a. Adding sand to eroding beaches Be able to identify the areas of sediment accumulation and erosion for groins and jetties in relation to the direction of longshore drift. 2. 2. 2. 2. o 2.  a. Groins: short structure built perpendicular to the shore, partway across the surf zone a. Accumulation of sediments b. Jetties: long structures built perpendicular to the shore What is beach nourishment? a. Soft stabilization--> replacing lost sand from longshore to rebuild beaches What is a tombolo? a. bar of sand or shingle joining an island to the mainland What is a breakwater and what is its purpose? a. Hard stabilization b. barrier built out into a body of water to protect a coast or harbor from the force of waves What is a rip current and how are they identified? a. area of sea where two different currents meet or where the water is extremely deep b. make the water very rough and dangerous a. Dark parts of water that draws you out to sea b. Typical speed = .5-2m/s a. Phelps can only swim 1.6 m/s b. Swim to side if caught in rip Be able to identify the likely source for sediment to a barrier spit  Up coast from marshes, deltas, dunes, beaches  Rivers and erosions from cliff Why are so many barrier beaches located along the east coast of the U.S.?  Shallow region offshore  Lots of sediments  Low wave activity Describe the seasonal changes for a typical beach on in the northeast  Summer: fair weather moves sand onshore  Winter: storms move sand seaward; nearshore sandbars protect coast by dispersing wave energy 1. Define the following terms  Beaches: deposits of unconsolidated sand or gravel that accumulate along shores subject to the high energy of wave action  Coastline: refers to the highest elevation on the continent affected by storm waves.  Shore: area from the low tide line to the coastline  Backshore: flat area from the high tide line to the coastline (=supratidal zone)  Foreshore: area from the low tide shoreline to the high tide shoreline (=intertidal zone)  Berm: flat area of sand that accumulates just above the high tide line.  Beach face: is the sharply inclined surface between the berm and the low tide terrace that is cut by waves during high tide  Dunes: linear ridges of unconsolidated wind-blown sand that accumulate above or beyond the reach of most storm wave, smaller grains of sand than found in backshore, help protect area from effects of waves  Over-wash fans: dunes are breached and fan-shaped accumulations of sand form on landside of the dunes  Nearshore/surf zone: between the low tide shoreline and where the breakers form  Sand bar: linear ridges of unconsolidated sand often serve to “trip” the incoming waves to start breaking; they are typically dynamic, shifting location and changing shape daily or seasonally. In the summer, the sand bars are closer to the shore. The breakers are gentler and move sand toward the beach. In the wintertime, the sand bars form farther away from the beach, tripping the breakers to reduce the force that large breakers exert on the beach. 2. Where are the two primary ice sheets which contain over 99% of freshwater ice located?  Greenland Ice sheet  Antarctic ice sheet 2. What is thermal expansion and how important a roll has it played in rates of sea level rise over the last few decades?  Change in volume of water due to a change in temperature--> increasing volume of the ocean with rising temperatures 2. What is Eustatic Sea Level Change  Any uniformly global change of sea level 2. What is subsidence? When it occurs do you observe relative sea level rise or fall?  Sinking of land  Sea levels rise 1. What is uplift? When it occurs do you observe relative sea level rise or fall?  Raising of land  Sea levels fall 1. What are isostatic changes in sea level and how are they different than eustatic changes in sea level?  Local changes in seas level  Implies NO change in volume of ocean 2. Be able to provide the definition for a Delta and where they occur (i.e. at the mouth of a river)  accumulations of sediment at the mouth of a river  they form where a river transports more sediment than can be carried away by longshore currents  flood plain and the marshes that border the distributary river channel(s) are biologically highly productive 2. Be able to pick out the top reasons for why deltas like are subsiding so quickly:  The delta is compacting under its own weight  Dams have reduced the sediment supply to the delta  Levees along the river have restricted the transport of sediment from the main river to the flood plain  Natural subsidence is being exacerbated by oil and fluid extraction from the delta 2. Be able to explain why sea level is falling in Alaska. Why is sea level rising on the Mississippi Delta at over 3 times the global average?  Alaska: tectonics form earthquakes rising with pressure and then sinking the land when released  Mississippi: extraction of water/oils sinks the land, making sea levels rise 2. What is an Estuary?  highly productive areas of the coast where the fresh water of a river meets the saltwater of the ocean (mouths of rivers, drowned river valleys, bays)

Anatomy of a Wave

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