System Earth Flashcards
what is the feedback factor (Daisyworld)?
ratio of equilibrium response to forcing to the response without feedback. The formula is (temp change with feedback)/(temp change without feedback)
between which values is the feedback factor?
0 and 1
what is a feedback loop?
a series of couplings arranged such that there is a round-trip of information
what is a positive feedback loop?
a loop that amplifies perturbation/ self enhancing
what is a negative feedback loop?
a loop that is self depreciating
what types of steady states do negative feedback loops form?
stable equilibria that are resistant to perturbations.
what types of steady states do positive feedback loops form?
unstable equilibria that is carried to a new state at the slightest disturbance.
can the daisyworld system resist to an increase in luminoisity?
yes, the equilibrium point just changes.
does an equilibrium coincide with optimum daisy growth?
rarely
what is Ekman transport?
the spiralling caused by the Coriolis effect whereby the net movement of the water is at a 90 degree angle to the wind.
what is upwelling?
a phenomenon that occurs at divergent points. The cooler water rises to the surface, bringing nutrients with it.
what is downwelling?
occurs in areas of convergence, the accumulation of water causes a sink process.
what is geostrophic current?
the current as a result of the coriolis effect, whic flows round the gyre clockwise in the Northern Hemisphere and vice versa.
why are gyres assymetrical?
due to vorticity
el nino year temperature anomalies
warm waters in eastern pacific
warm water upwelling in south america
wind flows west to east
more tropical storms in pacific, fewer in atlantic
la nina year temperature anomalies
east to west windflow
global temperature is lower
what causes increasing salt concentrations in oceans?
- evaporation of seawater from shallow seas.
- biological processes with animals
- chemical processes with reactions between seawater and volcanic rocks on the sea floor.
- fomation of sea spray. This salt is returned through rivers .
thermocline
temperature gradient within an ocean coloumn. This varies from 0 to 15 degrees in much of the world. decreases with depth
halocline
salinity gradient within an ocean column. increases with depth.
pycnocline
density gradient within the ocean column. Increases with depth.
AABW
Antarctic Bottom Water - very deep, cold, slow moving water
NADW
North Atlantic Deep Water - Evaporation occurs, increasing the salinity in this region, so it drops near Greenland.
what is the driving force of oceanic circulation?
global distribution of energy and indirectly by temperature differences.
which effect modifies surface ocean currents?
the coriolis effect.
where is cold saline water formed?
north atlantic and Weddell sea off Antarctica
what type of water sinks?
low temperature and high salinity
how does bottom water reach the surface?
through upwelling in another region - a large conveyer belt system.
what is the net effect of oceanic circulation?
redistribution of thermal energy across the globe.
describe the cryosphere
the frozen part of the Earth System. Includes glaciers, ice sheets, frozen lakes and rivers, sea ice and frozen ground.
how do glaciers move?
under the influence of gravity with ice flowing in response to ice-surface slope and by sliding over the bedrock.
how does sea ice move?
due to winds and ocean currents.