MSCI370 - Midterm 1

A midterm that covers **almost** everything on the midterm. Does not include discussion papers, presentation projects, and readings.

Describe the growth mindset

An idea that people believe that their most basic abilities can be developed through dedication and hard work—brains and talent are just the starting point

Define a Thermocline

A steep temperature gradient in a body of water. Each layer is defined by a different temperature reading.

Where do seasonal thermoclines occur?

They occur in bodies of water located in mid-high and mid-low latitudes

Define a pycnocline

A density gradient in a body of water. Each water layer is defined by their density.

Define a halocline

A salinity gradient in a body of water. Each water layer is defined by their salinity.

What is Salinity?

The total quantity of dissolved organic solids in water, measured in parts per thousand (ppt)

What would it mean if the ocean’s salinity was measured to be 34 ppt?

For every 1000 g of seawater, you would find 34 g of salt

What abiotic processes decrease water salinity?

Ice melt, precipitation

What abiotic processes increase water salinity?

Ice formation, evaporation

What significance does ice melt have in the polar regions of the ocean?

Ice melt adds a flux of freshwater into the surface seawaters, creating a layer of low salinity waters that prevents mixture between the cold surface waters and warm deep ocean waters

What does the Conductivity-Temperature-Depth Sensor do?

It’s an instrument that measures temperature and salinity at a given depth

What is a water mass?

A large body of water that is distinguishable by its characteristic narrow ranges of temperature and salinity (T-S Plot)

What is the purpose of a Temperature-Salinity Plot (T-S Plot)?

It helps us identify water masses based on temperature and salinity?

What do each of these graphs represent?

Thermocline, halocline, pycnocline (respectively)

What is the main point of the Equation of State?

Seawater is directly affected salinity, temperature, and pressure.

Based on the Equation of State, describe the relationship between density and salinity

Direct proportional relationship; density increases as salinity increases

Based on the Equation of State, describe the relationship between density and pressure

Direct proportional relationship; density increases as pressure increases

Based on the Equation of State, describe the relationship between density and temperature

Inverse proportional relationship; density increases as temperature decreases

Describe the variables and their units found in the equation for pressure (p).

p: pressure (kg m^-1 s^-2 or pascal, Pa),

ρ: density (kg m^-3),

g: gravity (m s^-2),

z: water column height (m)

Describe pressure gradient.

The direction and at what rate the pressure increases the most rapidly around a particular location

What is the density of seawater?

1026 kg/m^-3

How is the ocean productive if the water is separated by layers?

Processes, such as upwelling, can break through these layers

Why are the slopes of pycnoclines at sharp angles at certain locations of the ocean?

This is caused by the movement of currents that are powered by the Coriolis Effect

What is the Coriolis Effect?

An effect that occurs in a rotating system, where a moving object experiences a force that deflects them to the left (SH) or right (NH).

Why does the curve in the Coriolis Effect occur?

The change in speed relative to the Earth’s rotation

RELATIVE to Earth’s rotation. Are you moving slower or faster at the Equator? Why?

You are moving faster with Earth’s rotation because you have more distance to cover at the Equator.

RELATIVE to Earth’s rotation. Are you moving slower or faster in the Poles? Why?

You are moving slower with Earth’s rotation because you have less distance to cover at the Poles.

Describe the three rules for the Coriolis Effect

1\.) Any object moving horizontally is deflected to the left (SH) or right (NH)

2\.) The faster the object moves, there is more tendency for reflection

3\.) The tendency to deflect is greater at the poles, decreasing as you move towards the equator

If Earth is always spinning at high speeds, then why isn’t the ocean thrown off into space due to circular motion?

The oceans are still here because of gravity. Unchecked, the movement of water due to circular motion will go near the equator and develop into a bulge. However, since water loves to fill in space and along with gravity, water will flow out of the high-pressure bulge into areas with low pressure.

Describe the variables found in the equation for Coriolis Frequency or Parameter (f). Along with constant values, if applicable.

f: Coriolis frequency (s^-1)

𝛀: Angular velocity of earth (7.2921 × 10−5 rad s^-1)

θ = latitude (e.g., - 45 for 45°S)

What is the current Atmospheric Composition of modern-day Earth?

78% Nitrogen, 21% Oxygen, \~ 1% Argon, 0.036% Carbon Dioxide, \~ 4% Water Vapor

What happens to the Coriolis parameter (or Coriolis frequency) when you increase in latitude? How does it relate to the third rule of the Coriolis Effect?

If you increase in latitude, the Coriolis parameter would increase. This is consistent with the third rule of Coriolis, where there is a greater tendency deflect as you move towards the poles.

If the air is warm and less dense, then it will ____

rise

If the air is cool and more dense, then it will ____

sink

If the air is humid and less dense, then it will ____

rise

If the air is dry and more dense, then it will ____

sink

Describe the movement of air between the Hadley Cell, Mid-Latitude (Ferrel) Cell, and Polar Cell

Hadley Cell: The warm, low pressure air rises at 0 Lat. As the air cools down, it becomes more dense and sinks at 30 Lat.

Mid-Latitude Cell: The cool air from 30 Lat gets warmer as it reaches 60 Lat and rises up into the atmosphere.

Polar Cell: The rising warm air from 60 Lat moves towards 90 Lat, where it cools down and sinks back to the surface of the Earth.

Describe Ekman Transport

The net flow that is perpendicular to the wind direction (\~90 degrees)

How is Ekman Spiral related to Ekman Transport?

Ekman spiral is the flow of surface water 45 degrees (left or right, SH or NH) of the wind motion due to water movement being slower than the wind. Between the water layers, this creates changes in water flow that appear like a spiral.

What is Ekman Depth in relation to Ekman Spiral?

The Ekman Spiral “spirals” down in water motion until it reaches a maximum depth, Ekman Depth, in which the water column experiences no level of motion

How does Ekman Transport contribute to bulge formations in the ocean?

Tradewinds (E to W) and Westerlies (W to E) produce surface ocean currents that are perpendicular to the wind direction. These currents flow into each other, and through Coriolis acceleration, the currents form a circular flow because water is pushed out tangentially.

Describe Geostrophic Flow in relation to pressure gradients and Coriolis

This occurs when Coriolis balances the pressure gradient forces, creating a flow that is parallel to isobars. Here, water from areas with high-pressure flow into areas with low-pressure.

When water is displaced, what does it tend to do when there is empty space? Explain in terms of the pressure gradient.

Water will move from areas with high pressure to areas with low pressure

Describe a gyre system with respect to geostrophic flow

The Coriolis acceleration will make water flow tangentially from its initial direction, maintaining a circular flow around a bulge

What is Western Intensification?

A phenomenon in ocean gyres in the Northern Hemisphere, where the peak of gyres lies west of the gyre’s center

Why are western boundary currents faster than eastern boundary currents?

This is due to the change in Coriolis, or planetary vorticity, as latitude increases. This experience is more intense as you move poleward

Describe Geostrophic Flow on the west and east side of a gyre with respect to Western Intensification

Geostrophic flow is faster on the western side of an NH gyre due to the steep slope.

Geostrophic flow is slower on the eastern side of an NH gyre due to a gentle slope

Describe Western Boundary Currents and their average speed

Fast deep currents that transports large volumes of water and heat poleward (40-120 km d^-1, or 0.46-1.4 m s^-1)

Describe Eastern Boundary Currents and their average speed

Slow, thin currents that transports water southward (10 km d^-1, or 0.125 m s^-1)

Is there a difference in the volume of water transported on the western and eastern boundary currents?

There is no difference. The current on the western boundary current is thicker because water is more concentrated in a smaller area. The current on the eastern boundary current is thinner because water is spread out in a large area.

What are surface currents?

Ocean currents that are driven by atmospheric winds

Name the ocean currents found in the North Pacific Gyre

California Current, North Equatorial Current, Kuroshio Current, and North Pacific Current

Name the ocean currents found in the South Pacific Gyre

Peru Current, South Equatorial Current, East Australia Current, and Antarctic Circumpolar Current

Name the ocean currents found in the Subpolar Gyre (above N. Pacific)

Kamchatka Current, Alaska Current, North Pacific Current, Oyashio Current

How much of the air and the water circulates heat globally (percentage-wise)?

50% air, 50% water

Of the water that circulates heat, what percentage of heat is circulated by surface waters and deep waters?

10% surface waters, 90% deep waters

Where does the Thermohaline Circulation originate from, how does surface waters reach deep water?

It originates from higher latitude surface waters, where they cool down and become denser before sinking to deep waters

Describe deep ocean circulation

Has a slower flow with greater volume

Important for the heat transport budget

Major reservoir of CO2

What are the four water masses that we use in MSCI370?

North Atlantic Deep Water, Antarctic Bottom Water, Circumpolar Deep Water, Antarctic Intermediate Water

What water mass is associated with a temperature of 2-4 C and salinity of 34.9-35.0 psu?

North Atlantic Deep Water

What water mass is associated with a temperature of -0.8-2 C and salinity of 34.6-34.7 psu?

Antarctic Bottom Water

What water mass is associated with a temperature of 1-2 C and salinity of 34.62-34.73 psu?

Circumpolar Deep War

What water mass is associated with a temperature of 3-7 C and salinity of 34.2-34.4 psu?

Antarctic Intermediate Deep Water

What are the three terms to classify the distribution of seawater elements?

Conservative, Recycled (nutrient-like), Scavenged

What type of distribution has no change in concentration as depth increases?

Conservative

What type of distribution is in low concentrations at the surface waters, but increases as you go deeper?

Recycled (nutrient-like)

What type of distribution is in high concentrations at the surface waters, but drastically decreases into a minimum zone before stabilizing in deeper waters?

Scavenged

What is remineralization?

When organic material of a living organism is broken down into unrecognizable parts (complex → building blocks)

Define residence time

It determines the average length of time something will stay in a reservoir, assuming a steady state. (amount/(outflow or inflow))

Describe the Redfield Ratio, and the typical elements involved.

The ratio of two important nutrients relative to carbon in organic matter (C:N:P)

What does pH measure?

The number of protons in a given solution

What is the average pH of seawater? Is it acidic or basic?

8\.1, basic

Ocean acidification refers to the slight drops in pH levels for seawater. Why is that slight drop STILL significant?

Going from one pH level to another changes the # of protons in a solution on a logarithmic scale. A pH change from 8.1 to 7.9 is can be considered significant.

How does dissolution introduce gases into seawater

Dissolution mixes gases into water through pressure

What is a surfactant?

A chemical that can prevent the exchange of gases between the atmosphere and water

How does wind improve the Air-Sea Exchange of gases?

Wind injects bubbles into the sea surface and the pressured in deeper waters facilitate the diffusion process.

What makes CO2 special in terms of gas solubility with water?

CO2 is categorized as a low solubility gas but has a slow reactivity with water like a high solubility gas

Why does CO2 outgassing occur at high levels around the Equator?

The Intertropical Convergence Zone is an area moving winds pull the water away through Coriolis. Equatorial upwelling occurs to replace the lost water, bringing up a high \[CO2\] along with it

What is the Solubility Pump and how much CO2 does it account for in the ocean?

The physical mixing of CO2 across the air-sea boundary, it accounts for 90% of C in the ocean.

What is the Biological Pump and how much CO2 does it account for in the ocean?

The biological mixing of CO2 across the air-sea boundary, it accounts for 10% of C in the ocean.

Why is the Saturation State relevant to Oceanography?

Saturation State is used to track ocean acidification using molecules, such as CaCO3.

Why symbol is used to identify Saturation State?

The symbol is omega, or Ω

What would happen if you increased Ksp, the solubility product constant?

Increasing Ksp would decrease the saturation state of the seawater. A lower saturation state will stress out organisms that build shells and can eventually dissolve.

What would happen if you decreased Ksp, the solubility product constant?

Decreasing Ksp would increase the saturation state of the seawater. A high saturation state will promote shell development in CaCO3-producing organisms

Name the three main inorganic carbon chemicals in the ocean

carbon dioxide (CO2) {\*includes both CO2 and carbonic acid (H2CO3)},

bicarbonate (HCO3-),

carbonate ions (CO3^2-)

Of the three main inorganic carbon chemicals, which concentration is the most important to us?

Carbonate concentration is the most important because it is essential for the production of calcium carbonate (CaCO3)

How does the break down of dissolved inorganic carbons contribute to ocean acidification?

Each time the molecules break down, it introduces another proton into the seawater

What does Ksp represent? And what factors affect Ksp?

The level at which a solute dissolves in a solution. High Ksp = more solubility.

Ksp is affected by pressure, temperature, and salinity.

Which of the ions is mostly constant? Why?

The Calcium ion is mostly constant because it’s an element with a conservative distribution

Why are upwelling zones associated with low pH levels? Where do they occur?

Deep waters with low pH levels are brought up, resulting in low pH areas. This can be seen in the Eastern Pacific.

How do Oxygen Minimum Zones (OMZ) occur in the ocean?

OMZ occurs because of the oxidation of organic molecules. They are broken down from basic sugars back to CO2 and H2O at the cost of oxygen. At the same time, the pH level is lowered.

What is ocean acidification?

The increase in CO2 levels that decreases the overall pH level in the ocean

What are the biological consequences of ocean acidification?

Reduced calcification, increased metabolism, reduced sensory behaviors, reduced ecosystem structure

What are the carbonate forms from highest to lowest solubility at low pH levels?

Calcite, Aragonite, Magnesium calcite

Using the provided graph, what inference can you make about the relationship between the calcification rate of corals and the saturation rate?

As you decrease the saturation rate, we would expect the calcification rate of corals to decrease over time.

If you increased CO2 levels, what effect would you expect for the photosynthesis rate?

We would expect the photosynthesis rate to increase.

If you increased CO2 levels, what would you expect for the calcification rate?

We would expect the calcification rate to decrease.