Climates of the past; Oceanography Flashcards
Define the albedo effect
A measure of how much of the sun’s energy is reflected off an object back out to space compared to how much is trapped in Earth’s atmosphere
What drives the energy transfer and motion of the atmosphere and the ocean?
Heating imbalances in the oceans
How are surface waters moved?
By winds that blow in certain patterns because of the earth’s spin and the Coriolis effect
What is the Coriolis effect?
the pattern of deflection taken by objects not firmly connected to the ground, deflect to the right in the N hemisphere and to the left in the S hemisphere
What is an ocean gyre?
large system of circular ocean currents formed by global wind patterns and forces created by Earth’s rotation
Where are seasonal thermoclines formed?
At much shallower depths
Describe albedo
Albedo is a non-dimensional, unitless quantity that indicates how well a surface reflects solar energy. It has a value between 0 and 1.
What is a thermocline?
A thermocline is the transition layer in a body of water in which temperature changes more rapidly with depth than in the layers above or below
In the ocean, the thermocline divides the upper mixed layer from the calm deep water below
Describe a seasonal thermocline
formed at much shallower depths during the summer as a result of solar heating but destroyed by diminished isolation and increased surface turbulence in the winter
How are ocean surface circulations created?
driven by wind as a result of friction
What process is responsible for many large scale weather patterns?
The Coriolis effect
What is the Ekman effect?
when wind blows over the ocean, (when this happens, energy is transferred from the wind to the surface layers)
+ The change in wind direction with increasing height above the ground, or change in ocean currents with depth, that is determined by the Coriolis force
What is wind stress?
the frictional force of wind which acts on the ocean surface
What is the Ekman transport?
total volume of water transported at right angles to the wind direction per second
What is the Ekman layer?
- the upper layer of the ocean which is influenced by the wind
what does the Ekman theory predict?
- surface currents will flow 45 degrees to the surface wind path
- flow will be reversed at 100m below the surface
- flow at depth will be considerably reduced in speed
Where does coastal upwelling occur?
where Ekman transport moves surface waters away from the coast; surface waters are replaced by water that wells up from below.
What is the subtropical gyre?
a ring like system of ocean currents rotating clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere caused by the Coriolis Effect.
What is the gulf stream?
a western intensified current largely driven by wind stress and part of the thermohaline circulation
How does the Gulf stream work?
- As warm water flows from the equator to the poles it cools and evaporation occurs, this increases the amount of salt.
- Low temperature and a high salt content means high density and the water sinks deep in the oceans.
- The cold, dense water also moves slowly
- Eventually, it gets pulled back to the surface and warms by “upwelling” and the circulation is complete.
what is the thermohaline circulation also known as?
- the meridonial overturning circulation
Describe the thermohaline circulation?
Deep-ocean currents driven by differences in the water’s density, which is controlled by temperature (thermo) and salinity (haline)
How do the polar regions ocean water initiate the deep-ocean currents driving the global conveyer belt/ thermohaline circulation?
- The polar regions ocean water gets very cold, forming sea ice, surrounding seawater gets saltier,
- its density increases, and it starts to sink.
- Surface water is pulled in to replace the sinking water, which in turn eventually becomes cold and salty enough to sink. This initiates the deep-ocean currents driving the global conveyer belt.
How does CO2 get in the surface waters?
By the exchange of CO2 with the atmosphere
How are nutrients limited in the ocean’s surface waters?
- phytoplankton in surface waters use up nutrients and then die
- they sink into deep waters
- the decay and oxidation of sinking releases nutrient s back into the deep waters Not the surface
How can nutrients in the oceans be distributed to surface waters?
- by the process of upwelling, which is driven by Ekman transport
Name 2 highly productive biomes
- polar oceans and sea ice zones
Why are polar oceans highly productive ?
The formation and melting of sea ice is driven by seasonal changes and solar heating
What are diatoms?
- single celled plants responsible for most of the primary production in sea ice zones
Describe the albedo and temperature feedback system
- climate warming
- less sea ice = lowers reflectivity
- more solar radiation absorbed by ocean
- ncreased warming
