satan's massive oceanography flashcard set

basically just a combination of other people's flashcards, bound to be a lot of repeat terms in here, but it'll be good for you

What is transmitted by a wave?

Energy, not matter.

How is wave speed (c) calculated?

c = L / T, where L is wavelength and T is period.

What three main factors can force water surface displacement?

Low atmospheric pressure, gravitational attraction of sun and moon, and landslides/earthquakes.

What type of wave are tides classified as?

Kelvin waves.

Why does the moon generate a larger tidal force than the sun despite its smaller mass?

Tide-generating force is proportional to mass divided by distance cubed; the moon is much closer to Earth.

What is the approximate period of the dominant lunar (M2) tide?

12.42 hours.

What causes the 12.42-hour tidal period instead of exactly 12?

The moon advances about 12.2° eastward each day, so Earth must rotate an extra 50 minutes to realign.

Define spring tide.

A tide with the greatest range, occurring when sun, moon, and Earth are aligned (new or full moon).

Define neap tide.

A tide with the smallest range, occurring when the sun-Earth line is at right angles to the Earth-moon line (first and third quarters).

What is declination in a tidal context?

The angle between the plane of the moon’s orbit and Earth’s equatorial plane, varying 18.5°–28.5° over 18.6 years.

What is an amphidromic point?

A point in the ocean where the tidal range is zero and around which tides rotate.

Which coasts of New Zealand experience larger tidal ranges?

West coast generally shows larger ranges than east coast due to resonance and basin shape.

What is the difference between flood and ebb currents?

Flood current moves landward as tide rises; ebb current moves seaward as tide falls.

What is a tidal bore?

A wall of turbulent water that travels up a river or narrow bay during a strong flood tide.

What is the primary restoring force for long shallow-water waves such as tides?

Gravity.

What is geostrophic balance?

A state where horizontal pressure gradient force is balanced by the Coriolis force.

State the three ‘magic rules’ for Coriolis deflection.

Deflects right in NH, left in SH; magnitude increases with speed; zero at equator and maximum at poles.

Define inertial current.

A current that continues after the driving force ceases, moving in circles due to Coriolis; radius r = u / f.

What is the typical rotation direction of a Northern-Hemisphere hurricane?

Counter-clockwise due to Coriolis deflection toward the right.

Why can’t hurricanes form at the equator?

Coriolis parameter (f) is zero at the equator, preventing the necessary rotation.

Differentiate barotropic and baroclinic flows.

Barotropic: density surfaces parallel pressure surfaces; baroclinic: density varies horizontally causing tilted pressure surfaces.

Name two main sources for NADW formation.

Greenland Sea and Norwegian Sea (plus minor in Labrador Sea).

Give the characteristic T-S values for Antarctic Bottom Water (AABW).

Approximately –2 °C and 34.8 PSU.

What prevents deep-water formation in the North Pacific?

Lower surface salinity from reduced evaporation and cooler, moist air limits density increase.

What is subduction (oceanographic sense)?

Penetration of the pycnocline by downwelling surface water at a convergence.

What is the global conveyor belt?

The large-scale thermohaline circulation that links surface and deep waters worldwide.

Explain ‘brine rejection’.

Formation of saltier, denser water when sea ice freezes and expels salt.

Define buoyancy (Brunt-Väisälä) frequency.

The natural frequency at which a displaced parcel oscillates vertically in a stably stratified fluid.

What is salt fingering?

Small-scale mixing process where warm, salty water overlies cold, fresh water, forming downward salt ‘fingers’.

List the five major ocean water masses by depth.

Surface, Central, Intermediate, Deep, Bottom.

What does a T-S diagram show?

The temperature-salinity relationship used to identify water masses.

Why is seawater density usually reported as sigma-t?

To highlight small variations by subtracting 1000 kg m⁻³ from density measured at 0 dbar.

What is the CCD?

Calcium Carbonate Compensation Depth – depth where CaCO₃ dissolution equals supply.

Define lysocline.

Depth at which the rate of CaCO₃ dissolution begins to increase markedly.

What controls the depth of the CCD?

Supply rate of carbonate particles and water chemistry (temperature, pressure, CO₂ concentration).

State the three main types of marine sediments by origin.

Terrigenous (lithogenous), biogenous, hydrogenous (authigenic).

What is a turbidite?

Sediment layer deposited by a turbidity current, graded from coarse at bottom to fine at top.

Which organisms dominate calcareous biogenous sediments?

Foraminifera, coccolithophores, and pteropods.

Name two primary siliceous producers.

Diatoms and radiolarians.

What are manganese nodules?

Hydrogenous concretions rich in Mn and Fe oxides precipitated on abyssal plains.

Describe a piston corer’s purpose.

Collects long, relatively undisturbed sediment columns for geological analysis.

What is the Wilson cycle?

The sequence of opening and closing of ocean basins through plate tectonics, from rift to suture.

Differentiate active and passive continental margins.

Active: near convergent/transform boundaries, seismic & volcanic; Passive: along divergent boundaries, tectonically quiet.

Define continental shelf.

Gently sloping submerged extension of continent, usually <200 m deep.

What is an abyssal plain?

Very flat deep-ocean floor formed by fine sediment covering rough basalt topography.

Explain the SOFAR channel.

Depth of minimum sound speed where acoustic energy is trapped and can travel long distances.

What is residence time (chemical oceanography)?

Average time an element stays in the ocean = amount in ocean / input rate.

Why are Cl⁻ and Na⁺ termed conservative ions?

They have long residence times and uniform ratios, unaffected by biological processes.

Define scavenging (chemical).

Removal of trace elements from seawater by adsorption onto sinking particles or precipitation.

State the Redfield ratio.

Average atomic ratio of C:N:P in marine organic matter ≈ 106:16:1.

What is Liebig’s Law of the Minimum?

Growth is limited by the scarcest essential nutrient.

Identify one major anthropogenic carbon input to the ocean-atmosphere system.

Combustion of fossil fuels increasing atmospheric CO₂.

Explain ocean acidification.

Decrease of seawater pH due to absorption of excess atmospheric CO₂ forming carbonic acid.

What is the approximate modern average surface ocean pH?

About 8.1–8.3.

Why does cold water hold more dissolved gas than warm?

Gas solubility increases as temperature decreases.

What is a CTD?

An instrument measuring Conductivity, Temperature, and Depth to infer salinity and density.

How does pressure change with depth in seawater?

Approximately 1 decibar per meter (or 1 atm every 10 m) in the upper ocean.

Define thermocline.

Layer of rapid temperature decrease with depth separating warm surface from cold deep water.

What is pycnocline?

Layer of rapid density increase with depth, often coinciding with thermocline and halocline.

What is the mixed layer?

Near-surface ocean layer of uniform properties created by wind and waves.

Which property decreases when salt is added to pure water?

Freezing point (it is lowered).

Which property increases when salinity rises?

Water density, boiling point, surface tension, electrical conductivity.

Why does seawater freeze from bottom up only above 24.7 PSU?

Freezing temperature intersects density maximum temperature at about –1.33 °C for salinity 24.7 PSU; higher salinity means freezing requires whole column cooling.

What is osmotic pressure?

Pressure needed to prevent water movement across a semi-permeable membrane due to salinity difference.

Name three Earth orbital or positional factors affecting solar heating.

Latitude, season (axial tilt), distance from sun (perihelion/aphelion).

Define Hadley cell.

Tropical atmospheric circulation cell between equator and ~30° latitude, featuring rising air at ITCZ and sinking at subtropics.

What is the ITCZ?

Intertropical Convergence Zone – region of rising air and surface convergence near the meteorological equator.

Explain a sea breeze.

Daytime onshore wind caused by land heating faster than ocean, creating low pressure over land.

Explain a land breeze.

Nighttime offshore wind when land cools faster, producing higher pressure over land.

What is an extratropical cyclone?

Low-pressure storm formed along polar front between Ferrel and Polar cells.

Describe Ekman transport.

Net water movement 90° to the right (NH) or left (SH) of wind direction due to spiraling current layers.

What causes coastal upwelling?

Wind-driven Ekman transport moving surface water offshore and replacing it with deeper water.

Define ENSO.

El Niño–Southern Oscillation, climate pattern involving periodic warming of central/eastern tropical Pacific.

What is the average salinity of open ocean seawater?

About 35 PSU (ppt).

Name the six most abundant ions in seawater.

Cl⁻, Na⁺, SO₄²⁻, Mg²⁺, Ca²⁺, K⁺.

Describe the Forchhammer Principle.

Major ion ratios remain constant everywhere in the ocean, regardless of total salinity.

What instrument uses conductivity to estimate salinity?

Salinometer or CTD’s conductivity sensor.

Why do biolimiting nutrients show surface depletion?

They are consumed by photosynthetic organisms faster than they are resupplied.

Give two examples of bio-intermediate elements.

Barium (Ba) and radium (Ra).

Which latitudinal band shows the thickest sediment cover on continental shelves?

Mid-latitudes with large riverine input (e.g., Gulf of Mexico).

What forms a guyot?

Submarine volcano eroded to a flat top then submerged below wave base.

Where are most deep-sea trenches located?

Pacific Ocean, along subduction zones.

Why is the hypsographic curve bimodal?

Because continental crust is higher and less dense while oceanic crust is lower and denser, creating two elevation modes.

What is the average depth of the ocean?

Approximately 3,750 m.

Name one method to map seafloor bathymetry from space.

Satellite altimetry using sea-surface height anomalies.

What type of sediment dominates at high latitudes?

Siliceous ooze (diatom-rich).

Explain ‘marine snow’.

Aggregates of organic and inorganic particles sinking through water column, enhancing settling of fine material.

What is ice-rafted debris (IRD)?

Coarse sediments transported by icebergs and released upon melting.

State one economic importance of marine sediments.

Source of hydrocarbons (crude oil and natural gas) on continental margins.

Define residence time of water in the ocean.

~4,100 years (volume divided by river inflow rate).

What is excess volatile?

Element in seawater (e.g., Cl, S) present in greater amount than can be explained by river input, supplied by volcanism.

Describe catalytic reactions at hydrothermal vents hypothesis for life’s origin.

Life’s building blocks formed via reactions on mineral surfaces (e.g., pyrite) in vent environments.

What was the Great Oxidation Event?

Appearance of significant free O₂ ~2.4 Ga, causing major atmospheric and biological changes.

Define polynya.

Ice-free area within sea ice, formed by winds or upwelling, important for dense water formation.

What is the main driver of modern thermohaline circulation?

Density differences from surface heat and freshwater fluxes, especially at high latitudes.

Explain the biological pump.

Transfer of carbon from surface to deep ocean via biological production, sinking particles, and dissolution.

Why does CO₂ become more soluble at depth?

Higher pressure and lower temperature increase solubility.

What is the typical mixed-layer depth range?

10–500 m depending on season and location.

Define halocline.

Layer of rapid salinity change with depth.

Give an example of a conservative tracer used to track water masses.

Salinity or potential temperature.