Ocean - Water cycle Flashcards
Ocean cover ___% of Earth’s surface
71
Ocean max depth
11 km
The average depth of the ocean
4.5 km
The average volume of ocean
1.35 (10)^18 m3
Primary constituents of ocean salinity:
chlorine, sodium, sulfate, magnesium, calcium, potassium, bicarbonate
Sources of ions in the ocean
dissolved load delivered from land from rivers, and from submarine volcanic activity (at mid-ocean ridges)
Sinks of ions at the ocean
precipitation of minerals, sequestration by living organisms to produce shells, sorption of clay minerals, and reaction of basaltic seafloor rocks
precipitation removes the following ions from the oceans:
sodium, chlorine, sulfate
sequestration removes the following ions from the oceans
calcium, bicarbonate
Sorption of clay minerals removes the following ions:
potassium and sodium
The residence time of ions
The average time an ion spends in seawater
The residence time of ions depends on:
the flux of an ion into seawater and the rate at which the ion is removed from seawater
Distribution of salinity is high where:
high in regions of high evaporation and low precipitation
salinity is low where:
river water enters the oceans
Ocean currents play a major role in:
Ocean salinity
Ancient ocean composition
Iron concentrations (Fe2+) were higher in proterozoic seawater, and thick banded iron formations were deposited as atmospheric oxygen increased and iron oxidized
Areas on earth with the highest ocean temperature
Temperature is highest in the tropical pacific ocean and Indian oceans and decreases poleward
The distribution of ocean temperature depends on
ocean circulation and amount of sunlight it is exposed to
Temperature variation with oceanddepth
temperature decreases with depth
Why temperature decreases with depth
cold water is denser and therefore sinks
Thermocline
the upper zone of rapid temperature change in the oceans
Salinity increases with:
depth
Why salinity increases with depth
saline water is denser and sinks
Holocene
a region of rapidly shifting salinity change in the coean
Seawater density _____ as depth increases
increases
Why seawater density increases with depth
due to decreasing temperatures, increasing salinity, and compression of liquid water with depth
Pynocline
zone of rapid density change in the ocean
Ocean currents are caused by
air currents (wind) interacting with the surface of oceans, sinking of denser (colder or more saline) water, and due to the rotation of the earth
Deep currents are driven by
dense, cold, high salinity water descending at the poles
Thermohaline circulation
the result of the density-driven movement of water in the oceans
Thermocline circulation plays a critical role in controlling ______.
global climate
How does the sun drive ocean currents
the sun heats the planet unevenly, resulting in energy differences that lead to wind directions. Frication acting between wind and water drives water movenet.
Surface circulation is dominated by gyres driven by the ________.
Coriolis effect
Coriolis effect
The surface of the solid earth is rotating about its vertical axis everywhere but the equator. Objects moving in a straight line then appear to curve relative to the solid earth beneath them.
The earth is rotating ____ in the northern hemisphere
counterclockwise
The earth is rotating ____ in the southern hemisphere
clockwise
Objects moving in a straight line on the northern hemisphere appear to curve _____ relative to the earth beneath them
clockwise (right)
Objects moving in a straight line on the southern hemisphere appear to curve _____ relative to the earth beneath them
counterclockwise (left)
Ekman transport
The Coriolis effect causes wind-driven currents in the northern hemisphere to be clockwise of the actual wind direction. Deeper currents are progressively rotated CW because of slower water velocity. The net water movement is 90 degrees in the direction of the wind.
Overall average water movement is _____ to wind in the northern hemisphere
90 degrees clockwise
Overall average water movement is _____ to wind in the souhern hemisphere
90 degrees anti-clockwise
Upwelling
Movement of deep, nutrient-rich ocean water to the surface where transport direction is offshore.
Downwelling
occur where transport direction is onshore.
Biotic life has ___ productivity in areas of upwelling
high
Biotic life has ___ productivity in areas of downwelling
low
El Nino
Normally, the coast of south america is one where Ekman transport drives the upwelling of nutrients to the surface. During an El Nino, upwelling will decline and trade winds reverse in the west pacific having an effect on weather patterns.
In a normal year, surface currents off the coast of South America move ___, and Ekman transport causes ____ and movement of water ____.
northward
upwelling
offshore
In a normal year, trade winds ___ which halts ___.
stop/reverse
upwelling
Why El Nino is bad for fisheries
Water at the top few hundred meters warm-up lowering oxygen and nutrient concentrations due to slowed upwelling. Fish then have to go to greater depths to survive.
Red algae at the surface also cause mass death of fish.
El nino frequency
4 years
