Oceanography HWs

Identify the water mass noted on these oxygen sections.

"HIGH OXYGEN" label on top panel (Pacific Ocean) - AAIW "HIGH OXYGEN" label on bottom panel (Atlantic Ocean) - NADW

If the average concentration of dissolved gold in seawater is 4 ppq (4 parts per quadrillion by mass), what is the total value of all the gold dissolved in the ocean? Assume the mass of the entire ocean is 1.4 x 1021 kg, and the current price for gold is $1725 per ounce. (Since the concentration is given to one significant digit, your answer should be rounded to one significant digit).

$300 billion

This engraving is from Ernst Haeckel's classic book Kunstformen der Natur. Use morphology to select which TWO of the following copepods are adapted to living in warm waters.

- #1 (top center) - #8 (botton center)

Give the classical Redfield Ratio for C:N:P as given in lecture. ____C: ____N: ____P Given the following hypothetical seawater C:N:P ratios, which element is the limiting nutrient in each case? Give only the elemental symbol. 110C:14N:1P 150C:18N:1P 300C:25N:2P

- 106 - 16 - 1 - N - P - N

This figure shows the mean surface wind stress direction across the globe. Choose the coordinates where you predict coastal upwelling should occur, based on the direction of Ekman transport (choose all that apply).

- 30S, 110E - 20N, 60E - 30N, 120W

Assuming idealized atmospheric flow, where on this cross-sectional diagram of the Earth would you expect to see the ascending air that forms the rising limbs of the atmospheric convection cells? Choose all that apply.

- A - C

Why has fossil fuel CO2 entered the deep ocean through the North Atlantic first? (select all that apply)

- NADW forms there - surface waters there tend to have low pCO2

During the photosynthetic reaction 6CO2 + 12H2O + sunlight -> C6H12O6 + 6O2 + 6H2O electrons are transferred from the element _________ onto the element _________. The total number of electrons transferred during this reaction (as written with the above stoichiometry) is ________. In the first two blanks write only the element symbol.

- O - C - 24

Under what conditions is calcium carbonate more likely to dissolve? (Choose all that apply)

- cold water - high pressure (deep ocean) - less alkaline (more acidic) water

Select the elements that behave non-conservatively in seawater (choose all that apply).

- copper - barium - phosphorous

Which layers of the earth contribute to the lithosphere? (choose as many as apply)

- crust - mantle

As CO2 is added to seawater, indicate which of the following parameters increase (select all that apply).

- hydrogen ion concentration - DIC concentration

Place a check mark next to each of the scenarios that includes a change in heat content.

- radioactive decay in the Earth's interior, causing its temperature to rise - absorption of solar radiation by the ocean's surface, causing its temperature to rise

Which of these conditions might hypothetically lead to the formation of water masses that downwell into the deep ocean? Select all that apply.

- sea surface cooling - intense evaporation - sea ice formation

What would likely happen if you placed a freshwater fish into seawater? Choose three answers.

- the fish might try to drink seawater but would have no way to deal with the salt - water would osmose out of the fish and into the surrounding seawater - the fish would become dehydrated

As a wind wave approaches shore and becomes a transitional wave and then a shallow-water wave, which wave characteristics decrease in magnitude? Select all that apply

- wavelength - celerity

Return to the NASA GISS global maps page (http://data.giss.nasa.gov/gistemp/maps/ (Links to an external site.)) and make a map using all of the same options as in the previous question, except set the Land Surface Air Temperature to 'none.' This shows the magnitude of sea surface warming, calculated from linear trends beginning in 1975. The global mean surface ocean warming is given in the upper right corner. By how much has the global sea surface warmed since 1975?

0.61 C

Order these sediment grain sizes from smallest (1) to largest (4).

1 - clay 2 - silt 3 - sand 4 - granule

The Mid-Atlantic Ridge has a half spreading rate of 2.5 cm per year. How much farther apart will New York City and Lisbon (Portugal) be by the end of the semester (3.0 months from now)?

1.3 cm

This figure shows the recent history of the Southern Oscillation Index, with positive values indicating a strong sea level pressure gradient, and negative values indicating a weak gradient. For each of the years listed below, choose the ENSO state that you predict existed at that time.

1992 - el nino 1956 - la nina 1980 - neutral

If the sound waves in this cartoon take 2.0 seconds to travel from the ship to the seafloor, and another 2.0 seconds to return to the ship, approximately how deep is the water?

3.0 km

By one estimate, the 2004 Sumatran tsunami had a wavelength of 200 km and propagated toward Sri Lanka at a celerity of 180 m/s. Calculate the average depth of the Indian Ocean (between the Sunda trench and Sri Lanka) from this information.

3.3 km

If a wave has a wavelength of 20 m and frequency of 0.2 s-1, what is its period?

5 s

You hear on the radio that a monster storm located 400 km north of Hawaii has just started generating wind waves with maximum wavelengths of 150 m. Calculate how much time you have to get to the north shore of Hawaii and surf the first big waves. Assume that the waves spend their entire trip in deep (several km deep) water, and that there is no dissipation of wave energy as these waves propagate.

7 hours

In the Northern Hemisphere, the net motion of water in an Ekman spiral is _____ the wind direction.

90 degrees to the right of

Match the plate boundary feature to its letter on this map of the Aleutians.

A - overriding plate B - volcanic arc C - trench D - subducting plate

Which water mass is dominant at 30S and 1000 m deep?

AAIW

What is the best explanation for upwelling along the equator?

Coriolis has opposite sign in each hemisphere, so any near-equator easterly winds will create divergence

In cold regions, lakes often become stably stratified during the winter, with colder waters overlying warmer waters. In the ocean this type of stratification (colder overlying warmer) can happen only if salinity varies with depth. It cannot happen in the ocean if salinity is constant with depth. Briefly explain each of these three scenarios in terms of density stratification. Neglect the possible role of ice formation. The following are student responses from a previous year. Some of them may not be technically wrong but are incomplete explanations. Choose the best, most complete explanation.

In the lake scenario, colder water is capable of overlying warmer water because the maximum density that freshwater can reach is at 4 degrees Celsius. This means that water colder than four degrees Celsius will be less dense and will lie on top of 4 degrees Celsius water. Unlike freshwater, seawater will gain more density until about -2 degrees Celsius. This means that the only way that colder water can lie on top of warmer water is if the cold water is less dense due a lower salinity. When salinity is constant, the colder water will 100 percent of the time be more dense, thus making it so it cannot overlie warmer waters.

Match the region to the explanation for its high or low chlorophyll concentration (use each choice only once).

North Atlantic subpolar gyre - ekman divergence (upwelling) due to polar easterlies and mid-latitude westerlies North Pacific subtropical gyre - ekman convergence (downwelling) due to mid-latitude westerlies and northeast trades Eastern equatorial Pacific - ekman divergence (upwelling) due to coriolis changing sign West coast of Peru - upwelling due to southerly winds

After lead was phased out of gasoline, why was its dissolved concentration in the upper ocean able to decline so rapidly (within a few decades)?

Pb has a short residence time in the ocean

Match the challenge to its adaptation among marine organisms (use each choice only once).

Remaining near the sea surface (for plankton) - small size Swimming through viscous seawater (for nekton) - large size and streamlined shape Maintaining neutral buoyancy (for fish in the upper ocean) - air filled swim bladder Maintaining neutral buoyancy (for fish in the deep ocean) - fatty organ

Seawater is denser than fresh water. A ship sailing from the Atlantic Ocean into the Great Lakes moves from seawater into fresh water. Will the ship sink deeper into the water during this passage, stay the same level, or rise slightly? The following are student responses from a previous year. Some of them may not be technically wrong but are incomplete explanations. Choose the best, most complete explanation.

Salt water is more dense than fresh water so the ship will sink deeper when it sails into fresh water. The floating ship displaces exactly its own weight in water, so it will displace a smaller volume of the denser salt water than it would the less dense fresh water.

Briefly explain how the large sand spit at the top of this image formed. Include the approximate direction of prevailing waves (assume that North is 'up'), and the reasons for longshore sediment transport and deposition. Use the terms swash and backwash in your answer. The following are student responses from a previous year. Some of them may not be technically wrong but are incomplete or unclear explanations. Choose the clearest, most 'expert' explanation.

The direction of prevailing waves is from north-west to south-east. The swash hits the beach at this angle, and grabs sediment as it moves directly down the beach (backwash), creating longshore sediment transfer. When the longshore current hits open water, it slows and loses its sediment, creating the sand spit.

Consider the case of a circular sea surface high in the Southern Hemisphere. Will the geostrophic flow around this high be clockwise or counter-clockwise? Explain your answer by describing the balance of forces. The following are student responses from a previous year. Some of them may not be technically wrong but are incomplete or unclear explanations. Choose the clearest, most 'expert' explanation.

The geostrophic flow will be counter-clockwise. This is because the pressure gradient force moves outward from the high to the areas around it. The Coriolis force balances the pressure gradient force meaning it is directed towards the high. In the Southern Hemisphere the Coriolis acts 90 degrees to the left of the flow, meaning the high will be on the left of the counter-clockwise flow.

Why do volcanoes form near subduction zones?

Water from the subducting plate lowers the melting temperature of mantle rock

This diagram shows the difference between Spring tides and Neap tides. Based on this geometry, and following the equilibrium theory of the tides, characterize a Neap low tide in comparison to a Spring low tide.

a neap low tide will be higher than a spring low tide

Which condition does not characterize El Niño?

a shallower thermocline in the eastern equatorial Pacific

Go to the NASA GISS global maps page (http://data.giss.nasa.gov/gistemp/maps/ (Links to an external site.)). Set Map Type to 'Trends,' Mean Period to 'Annual (Jan-Dec),' and Time Interval to 1975-2020. Leave all other settings at their default values, and then hit 'Make Map.' This shows the magnitude of the warming over all parts of the Earth's surface, calculated from linear trends beginning in 1975. The global mean surface warming is given in the upper right corner. Which of the following regions has warmed the most over that time?

arctic

Why do ocean waves get refracted as they approach shore?

because waves slow down when they begin contacting the seafloor

Once surface waters become dense enough to form deep waters, what is the most likely reason that their temperature would change significantly in the deep sea?

by mixing with other water masses

Match the organism to the mineralogy of its shell.

calcite - planktonic foraminifer aragonite - pteropods opal - diatoms

This map shows topography and bathymetry as colors, and crustal thickness as contours (in km). What regions tend to have the thickest crust?

certain continental mountain ranges

Match the organism to its habitat/mobility classification.

copepod - plankton shark - nekton sea star - mobile benthic coral - sessile benthic coccolithophore - plankton

Match the geologic feature to its color as represented on this multibeam bathymetric map.

dark blue - abyssal plain light blue - continental rise green/yellow - continental slope red - continental shelf

What is likely to be the greatest potential impact of future ocean acidification?

difficulty for biological CaCO3 formation

The subpolar gyres are biologically productive due to upwelled nutrients. Why is there upwelling in these regions?

ekman divergence due to the westerlies and polar easterlies

Seafloor topography can be mapped by satellite sensors that use:

electromagnetic waves that bounce back to the satellite from the sea surface

Go to the NOAA Bathymetric Data Viewer (Links to an external site.). At upper left, uncheck "Multibeam Surveys" and "NOAA NOS Hydrographic Data." At upper right, select the Basemap "Global Multi-Resolution Topography (GMRT) Data Synthesis (LDEO)." Now you can see the best resolution bathymetry data available.Find Georges Bank off the coast of the northeast United States. Southeast of Georges Bank you will see a series of seamounts. How do you think these seamounts formed?

form a hotspot

Match the eastern boundary current to the western boundary current found in the same gyre.

gulf stream - canary current kuroshio - california current brazil current - benguela current east australian current - peru current agulhas current - west australian current

Match the geologic process to its mode of heat transfer.

heat carried ip through the mantle by flowing mantle rock - convection heating of the lithosphere by the mantle - conduction loss of heat to outer space - radiation

Which characteristic is NOT typical of black smoker hydrothermal vent fluids?

high dissolved oxygen

Which factor does not contribute significantly to wind wave growth?

high salinity

While the side of Earth facing the moon has a high tide, the opposite side of Earth will simultaneously have:

high tide

What phase(s) is water in along segment B?

ice and liquid

Look at this real-time animation of surface ocean currents (Links to an external site.). What large-scale sea surface pressure do you expect to find in the blue (slow-moving) area just south of Greenland's southern tip, due to prevailing winds?

low (depressed sea surface)

Match each feature on these pCO2 maps to its main cause.

low pCO2 in North Atlantic subtropical gyre during February, compared to August - low temperature high pCO2 in eastern equatorial Pacific - upwelling low pCO2 in Southern Ocean during February, compared to August - high productivity

If each of the elements below had exactly the same input rate to the ocean (in mass per unit time), which one would have the longest residence time? Assume that all of them are at steady state.

magnesium

What tidal pattern would you expect the island in this cartoon to experience?

mixed semidiurnal

Rank the components of DIC in order of their abundance.

most abundant - bicarbonate second most abundant - carbonate least abundant - carbon dioxide

Characterize the heat absorbed by the ocean in recent decades:

much more than the atmosphere

Assuming idealized atmospheric flow, name the type of prevailing surface wind that you would expect to find at position F.

northwesterlies

The colored 'stripes' on this seafloor map indicate normal magnetic polarities of different ages, and white indicates reversed polarity. What type of plate boundary is indicated by the heavy dashed lines?

ocean ridges

How do most organisms retrieve stored energy from sugars?

oxic respiration

Which curve on this plot correctly shows how the Coriolis parameter varies with latitude?

red

Why does wave action tend to straighten shorelines?

refraction focuses wave energy on headlands

Match the marine organism to its kingdom.

seaweed - protista mangrove tree - plantae sponge - animalia coccolithophore - protista foraminiferan - protista clam - animalia

Match the wave characteristics (use each choice once).

shallow water wave crest morphology is - pointed shallow water wave orbits are - flattened shallow water wave depth is - <1/20 of the wavelength shallow water wave celerity depends on - water depth a wave is in contact with the seafloor only at water depths of <1/2 of the wavelength - deep water wave celerity depends on - wavelength deep water wave orbits are - circular deep water waves break at heights of - >1/7 of the wavelength

You measure a seawater sample with a dissolved chloride concentration of 16.3 per mil (parts per thousand by mass). Use this information to predict the dissolved concentrations of the elements below.

sodium - 9.1 per mil silicon - cannot tell from this information

Where does most of the heat in ocean waters originate?

solar radiation

Characterize the likely seafloor slope associated with this wave.

steep

Look at this real-time animation of surface ocean currents (Links to an external site.). Characterize the narrow, fast current off the east coast of southern Japan.

subtropical gyre western boundary current

Why is the Sun's effect on Earth's tides only about half that of the Moon?

the sun us much further away than the moon

Why are larger terrigenous sediment grains generally found close to shore, compared to fine terrigenous grains in the deep sea?

there is not enough energy to transport large grains far away from shore

The presence of a strong pycnocline is most often due to a strong ________.

thermocline

For each region noted on the map, match the best explanation for the thickness of sediments there.

thick sediments at A - very high riverine input thick sediments at B - very old ocean crust thin sediments at C - most calcium carbonate is dissolved thin sediments at D - very young ocean crust

What two crustal parameters do the "Airy" and "Pratt" models of isostasy argue are most important, respectively?

thickness and density

This cartoon is a very simplified representation of the meridional overturning circulation, or "ocean conveyor belt." It shows deep upwelling in the Indian and North Pacific Oceans. What is the main source of energy driving that upwelling?

tides

This diagram shows which wavelengths of electromagnetic radiation are absorbed by the major Greenhouse gases. Compare this to the diagrams shown in the lecture 'Earth's energy (im)balance.' Which gas is mainly responsible for absorbing some of the incoming infrared radiation from the sun?

water vapor

Assuming these waves were generated by a distant storm, why do they look so uniform? (the dark lines are wave crests)

waves with long wavelengths travel faster