ERTH 307 Final

Question 1

Surface Temperature and Salinity Patterns

Answer 1

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

Question 2

Temperature and Salinity Effects on Density

Answer 2

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

Question 3

Ocean Pressure

Answer 3

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

Question 4

General Wind Patterns at the Ocean’s Surface

Answer 4

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

Question 5

High/low Pressure Zones

Answer 5

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

Question 6

Wind Driven Gyres

Answer 6

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)

Question 7

Ekman Transport

Answer 7

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

Question 8

Coastal Upwelling (pnw)

Answer 8

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

Question 9

Coriolis Effect

Answer 9

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

Question 10

Geostrophic Currents

Answer 10

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

Question 11

Gulf Stream Rings

Answer 11

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

Question 12

Tide-generating Forces

Answer 12

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)

Question 13

Types of Tides

Answer 13

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

Question 14

Equilibrium Theory

Answer 14

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

Question 15

Wave-generating Sources

Answer 15

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

Question 16

Wave Energy Sources

Answer 16

Wind -
Tides -
Seismic -

Question 17

Wave Characteristics

Answer 17

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?

Question 18

Shallow Water Waves

Answer 18

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

Question 19

Deep Water Waves

Answer 19

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)

Question 20

Types of Waves

Answer 20

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

Question 21

Wave refraction

Answer 21

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

Question 22

General Pattern of Conveyor Belt

Answer 22

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

Question 23

Deep Ocean Water Masses

Answer 23

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)

Question 24

Temperature and Salinity Diagrams

Answer 24

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

Question 25

Thermohaline Relation to Ocean Circulation

Answer 25

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)

Question 26

Plankton vs Nekton

Answer 26

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

Question 27

Plankton

Answer 27

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

Question 28

Benthic vs Pelagic

Answer 28

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

Question 29

Primary Production: Photosynthesis

Answer 29

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)

Question 30

Limits of primary productivity

Answer 30

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)

Question 31

Photosynthesis

Answer 31

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)

Question 32

Limits of Primary Production

Answer 32

Can be limited by light and nutrients

Question 33

Seasonal Blooms

Answer 33

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

Question 34

Food Chain

Answer 34

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.

Question 35

Gelatinous zooplankton

Answer 35

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

Question 36

Concept Mapping: positive/negative feedbacks

Answer 36

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

Question 37

Marine Heatwaves

Answer 37

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

Question 38

Effects of the Blob: Biology

Answer 38

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

Question 39

Jelly blooms

Answer 39

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)

Question 40

Hypoxia

Answer 40

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