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Winter Term 2023 > ERTH 307 Final > Flashcards

ERTH 307 Final Flashcards

1
Q

Surface Temperature and Salinity Patterns

A

Vary in time and space
Vertical variations exist in both
Horizontal variations in T and S change in time, but major patterns exist

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2
Q

Temperature and Salinity Effects on Density

A

Temperature ↑, Density ↓ (inversely related)
Salinity ↑, Density ↑ (directly related)
Can cause density variates that can affect ocean currents

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3
Q

Ocean Pressure

A

Increases exponentially
1 atmosphere of pressure added every 10 meters down you go
Water is denser the farther down you go; gets even denser if it is cold and salty

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4
Q

General Wind Patterns at the Ocean’s Surface

A

Steady winds produce waves and set the surface water into motion
This starts the motion of the main surface gyres of the ocean

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5
Q

High/low Pressure Zones

A

High Pressure - Polar Cells; high pressure and low precipitation
- Cold, dense air
- Subtropical highs, polar highs
- Dry, clear, fair
Low Pressure - Equatorial region; Hadley cells; high precipitation
- Warm, low density air
- Equatorial lows, subpolar lows
- Cloudy, precipitation

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6
Q

Wind Driven Gyres

A

5 large gyres - N. Pacific; S. Pacific; N. Atlantic; S. Atlantic; Indian Ocean
Antarctic Circumpolar Current (West wind drift)
Equatorial countercurrent
Velocities vary (fastest are ~meters/sec)

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7
Q

Ekman Transport

A

Fundamentally due to Coriolis
Affects surface layer of ocean only (i.e. due to winds)
Average transport is perpendicular to wind (right in NH)

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8
Q

Coastal Upwelling (pnw)

A

Upwelling - vertival movement of deep waters to the surface
These deep waters are typically cold, nutrient-rich, oxygen-poor
In PNW, upwelling happens in the summer; winds blow from north, Ekman transport moves surface water offshore, to be replaced by deeper water
Summer upwelling leads to cooler coastal ocean temperatures; higher productivity = more chlorophyll

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9
Q

Coriolis Effect

A

Changes the intended path of an object
Causes all moving objects on Earth to follow curved paths; result of Earth’s rotation and spherical shape
To the right in the Northern Hemisphere (clockwise)
To the left in the Southern Hemisphere (counterclockwise)
Things travel different speeds at different latitutdes
Effect is strongest at poles and weakest at equator
Technically, the Earth moves, NOT the object, the object only appears to move

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10
Q

Geostrophic Currents

A

Geostrophic - balance between pressure gradient and Coriolis
Coriolis Deflection (Ekman Transport) plus the Pressure Gradient steers currents around gyres
Mound of water

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11
Q

Gulf Stream Rings

A

Cold core eddy - rotates counter-clockwise; 3 layers of depth
Warm core eddy - rotates clockwise; 4 layers of depth

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12
Q

Tide-generating Forces

A

Tide-generating forces created by Sun and Moon create bulges (get high and low tides dependent on position)
Difference between centripetal and gravitational is the resultant force
Resultant force = tide-generating force (~one millionth gravity)

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13
Q

Types of Tides

A

High - when the crest of a wave reaches a particular higher location due to the moon and sun’s gravitational pull on Earth
Low - when the crest of a wave reaches a particular lower location due to the moon and sun’s gravitational pull on Earth
Spring - constructive pull between sun and moon; happens when moon is either full or new and in line with the Earth and the sun
Neap - destructive between sun and moon; happens when moon is either first-quarter or third-quarter; moon is not in line with the Earth and sun
Diurnal - one high tide and one low tide in the day
Semidiurnal - two high and two low tides
Mixed - two high and two low tides; high high and low high, high low and low low

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14
Q

Equilibrium Theory

A

Developed by Newton in the 17th-century
Assumptions:
- Uniform ocean depth and coverage
- 2 equal tidal bulges
- No continents
- No friction between ocean and seafloor
Combined sun and moon bulges; get both sun and moon bulges that interact
Took into account:
- Moon’s angle to Earth (declination)
- Moon and Sun move in elliptical paths
Tide-generating forces created by sun and moon create bulges

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15
Q

Wave-generating Sources

A

Wind
Tides
Seismic activity
Disturbance caused by some energy source that moves through a medium
Disturbing and restoring forces
Progressive waves: orbital waves

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16
Q

Wave Energy Sources

A

Wind -
Tides -
Seismic -

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17
Q

Wave Characteristics

A

Crest, trough, wavelength (L), still water level, wave height (H)
Wave steepness = H/L (height over wavelength)
Wave frequency - 1/period
Measuring wavelength - how far from one crest to the next?
Measuring period - how much time between once crest and the next?
Measuring frequency - how many crests pass by a point in a certain amount of time?

18
Q

Shallow Water Waves

A

Effect on speed (S): whether the wave can feel the bottom
Depth of water (d) much LESS than wave base
d < L/20
Tides travel as shallow water waves; tsunamis are shallow water waves
Wavelength is set by disturbing force; very long wavelength and period

19
Q

Deep Water Waves

A

Effect on speed (S): whether the wave can feel the bottom
depth of water (d) GREATER than wave base
d> wave base; d> L/2 of waves by wavelength)

20
Q

Types of Waves

A

Breaking waves: spilling, plunging, and surging
- Spilling breaker - gentle slopes; water slides down wave slope
- Plunging - moderate slopes; curling, “barreling” crest; fun for board surfers
- Surging - steep slopes; waves break on shore; best for body boarders and surfers; sneaker waves
Tsunamis: very long wavelength and period, typically like 200km
Swell: waves generated by distant storm; uniform; long period; comes near parallel
Chop: local waves near storm; choppy; variable period

21
Q

Wave refraction

A

Waves approach at whatever angle they were traveling in deep water
Wave crests bend in shallow water (S is proportional to d)
Nearly parallel when hit shore

22
Q

General Pattern of Conveyor Belt

A

Surface waters at high latitudes form deep water
Deep water sinks and flows at depth throughout all major ocean basins
Deep water upwells to replace sinking surface water
Surface waters must move poleward to replace sinking water
Dense water doesn’t form in other oceans because:
- Pacific - too low salinity
- Indian - too high temp
- Arctic - some dense water formation, but small volumes and it stays in the Arctic Basin

23
Q

Deep Ocean Water Masses

A

Water masses change little once they are deep
AABW (Antarctic Bottom Water) spreads along bottom as it is denser than NADW (North Atlantic Deep Water)

24
Q

Temperature and Salinity Diagrams

A

Temperature ↑, density ↓
Salinity ↑, density ↑
Pressure ↑, density ↑

25
Q

Thermohaline Relation to Ocean Circulation

A

Density driven flow
Surface and deep ocean circulation carry heat poleward
Deep ocean responds to surface circulation:
- Resulting gyres move heat and salt
- Resulting density variations leads to vertical flow (sinking)
- Formation of water masses characterized by their temperature and salinity (= density)

26
Q

Plankton vs Nekton

A

Plankton - ‘plankton’ - wandering; these are organisms that cannot swim, they float around mostly, carried by ocean currents, waves, etc.
Nekton - ‘nektos’ - swimming; these are organisms capable of moving independently through the ocean
Do not photosynthesize; eat other organisms that do photosynthesize

27
Q

Plankton

A

Two main groups:
Phytoplankton - typically microscopic algae that create their own food
Diatoms, Coccolithophores, Dinoflagellates, Radiolarians
Zooplankton - typically small organisms that consume phytoplankton

These plankton occur in the pelagic realm and make up >99% of biomass in the ocean and are a critical step in the food web

28
Q

Benthic vs Pelagic

A

Benthos - ‘benthos’ - bottom; these are organisms living on or near the seafloor
Infauna - animals that live within the seafloor
Epifauna and Epiflora - animals that live on the surface of the seafloor
Pelagic - open ocean

29
Q

Primary Production: Photosynthesis

A

Amount of organic carbon (those sugars in photosynthesis) produced by phytoplankton (and to a very small degree by chemosynthetic plankton)
Gross primary production (GP): total amount of organic carbon produced by phytoplankton per unit time
Net primary production: GPP-R (goes into growth and reproduction)

30
Q

Limits of primary productivity

A

Light:
Depth of penetration (photic zone)
Amount of particulates in the water (organic and inorganic)
Intensity (season, latitude)
Cloud cover
Nutrients (nitrate, phosphate, silicate, etc):
Leads to seasonal patterns of phytoplankton in ocean
Modulated by upwelling of out coast
Nitrate is an important limiting nutrient
In coastal ocean, can have heavy nutrient loading due to humans (or natural processes like upwelling)

31
Q

Photosynthesis

A

Process by which phytoplankton produce food using energy from the sun (some plankton in deep ocean are chemosynthetic - they use chemical reactions based on hydrogen sulfide instead of sun’s energy)

32
Q

Limits of Primary Production

A

Can be limited by light and nutrients

33
Q

Seasonal Blooms

A

Phytoplankton - peaks in the March (spring bloom) when sunlight is going up; starts going down in late March/early April; zooplankton peak in April because they eat the phytoplankton; second phytoplankton peak in September (fall bloom)
Part of normal season abundance patterns for jellyfish
Can result from ‘abnormal’ environmental conditions:
- Coastal nutrient run-off
- Overfishing
- Climate change
- Non-native introductions

34
Q

Food Chain

A

Phytoplankton photosynthesize
Zooplankton eat phytoplankton and animal feces
Microbial Loop: the dead organisms sink to the bottom; nutrients comes up to the surface; zoo plankton are eaten by birds, fish, whales, seals, etc.

35
Q

Gelatinous zooplankton

A

Key members of ocean ecosystems
95% or more water
Planktonic lifestyle
Can form blooms - reputation of ecological disturbance

36
Q

Concept Mapping: positive/negative feedbacks

A

Diagrams that show ideas or concepts as nodes (ovals) which are connected by way of relationships (arrows)

37
Q

Marine Heatwaves

A

Cold blob: record cold temperatures in the North Atlantic
- Increased freshwater input from the Greenland Ice Sheet
- Less down welling and deep water formation in the North Atlantic
- Decrease in AMOC (Atlantic Meridional Overturning Circulation)of 2.7 Sv (1 mill. cubic m per sec) measured, but short record
- Natural variability could also be the cause
– North Atlantic Oscillation
– Atlantic Multidecadal Oscillation
Warm Blob: record warm temperatures in the North Pacific Ocean (at its peak in 2015)
- Driven by atmosphere
- Linked to weather patterns that include long-lived T-storms near New Guinea

38
Q

Effects of the Blob: Biology

A

Plankton Blooms:
- Bottom up foodweb effects
- Harmful blooms
Warm water species moving north
- Jellies, mola mola, mackerel, pelagic red grab
Cold water species suffer
- Salmon preyed upon
- Other fish move to deeper water
Also had effects on PNW climate; linked to drought conditions in 2014-2015

39
Q

Jelly blooms

A

Blooms are part of normal seasonal abundance patterns
- Can take advantage of optimal conditions - self-propagation in ctenophores, asexual reproduction in jellyfish or aggregation
- Put on size rapidly (mostly water)

40
Q

Hypoxia

A

Oxygen is not available in the amounts needed for organisms to survive

Winter Term 2023 (4 decks)

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