Intro to Oceanography Exam 1
what is the difference between a short and long residence time?
- longer residence time = unreactive ("conservative"), higher concentration in seawater - short residence time = insoluble or reactive, smaller concentration in seawater - steady state = ocean salinity nearly constant through time
what is the normal measurement of density in fresh water and sea water in sigma t?
0 = freshwater 28 = seawater
deep ocean temperatures are usually between what?
0 to 4 degrees centigrade
what are the 2 main sources of dissolved material (salt) in the ocean?
1) chemical weathering on land 2) hydrothermal weathering on the ocean floor
what are the 2 reasons why ocean waters are colder with increasing depth?
1) cold waters are denser than warm waters and, hence, tend to sink 2) deep waters are generated at high latitudes, where surface waters are cold, and then sink and flow beneath warm equatorial surface waters
what 4 things are ocean surface salinity controlled by?
1) evaporation - increases salinity 2) freshwater runoff - reduces salinity 3) atmospheric transfer of water vapor (freshwater) - across Central America 4) Sea-ice formation - increases salinity
where are the lowest areas of salinity?
1) high latitudes 2) North Pacific and Southern oceans
seawater temperature variation is controlled by what 3 things?
1) latitude (cold waters in Arctic and Southern oceans) 2) global deep ocean circulation 3) inflow of warm Mediterranean Intermediate Water (MIW)
what are the 3 ocean layers?
1) mixed surface layer 2) pycnocline / thermocline 3) deep ocean
what are 2 sources of salt added to oceans?
1) river input (primarily) 2) circulation through mid-ocean ridges
what are the 3 ways salinity changes?
1) salinity changes by adding or removing water 2) salinity decreases by precipitation (rain/snow), river runoff, melting snow 3) salinity increases by evaporation and formation of sea ice
what are 4 "sinks" of the ocean? (salt removed)
1) salt spray 2) recycling through mid-ocean ridges 3) biogenic sediments 4) evaporite formation and burial
density of seawater is controlled by what 3 things?
1) temperature 2) salinity 3) pressure - density increases with decreasing temperature, increasing salinity, and increasing pressure
what is the range of percent of salinity in the ocean?
32% - 37%
what is typical seawater salinity?
35 ppt (parts per thousand)
what percentage sodium chloride is sea water?
80%
who gave the first calculation of residence time? what is it?
John Joly, 80-100 million years old
where are the areas of highest salinity located?
North Atlantic (main source of ocean deep waters)
where are the areas of lowest salinity located?
North Pacific (strong freshwater input to surface here)
what happens to density as you go down the ocean?
always increases
what is the reservoir theory?
analyzes the movement of material between different reservoirs in the Earth system. It is a powerful tool for evaluating changes in ocean chemistry
major transfers of energy to atmosphere occur when?
as water vapor is converted to liquid water during the precipitation process
which ocean's surface waters have the most salinity?
atlantic
what is residence time?
average length of time a substance remains dissolved in seawater
what is the word to describe less than sea water salinity? < 33 ppt
brackish (hyposaline), usually results from mixing with freshwater, as in coastal areas
what is the dominant dissolved material in salt water?
chloride (anion = negative charge)
what is the relationship between temperature of seawater and density?
cold water = high density warm water = low density
how is density measured?
conductivity
what is the ability conduct electricity called?
conductivity
what does a CTD instrument meausure?
conductivity-temperature-depth
there is _____________ change in density as you go down the coean
continuous
what is the layer called of the ocean between 1000 meters and the bottom?
deep water - uniform variation
what controls ocean circulation?
density
what are the 3 major properties of seawater?
density, temperature, and salinity
evaporation tends to be stronger at what side of ocean basins?
east side - where cold equatorward-flowing currents are located
climate belts are due to what?
global-scale atmospheric circulation
what is a rapid change of salinity with depth called?
halocline
what are the 3 different names for the different types of gradients?
halocline = salt gradient thermocline = temperature gradient pycnocline = density gradient
density flows can carry a lot of fine material in suspension, producing a deposit after the material rains out, what is this deposit called?
hemipelagic deposit
the greater the amount of salt, the ____________ the conductivty
higher (salt water = conductive)
how does conductivity show amounts of salinity?
higher concentrations of dissolved salts result in higher electrical conductivity
what is the word to describe greater than sea water salinity? > 38 ppt
hypersaline, usually results from strong evaporation
what layer of the ocean has the most rapid change?
intermediate layer
what is the layer called of the ocean between 200 meters and 1000 meters water depth?
intermediate layer - very rapid changes in properties, big changes in salinity, temperature, and density
what is a line of equal density on a TSD diagram called?
isopycnal
what is a line of equal temperature called on a graph?
isotherm
temperatures are lower in the south polar region than the north polar region, why?
landmass - temperature extremes are greater over land areas (Antarctica) than over oceans, such as the Arctic Ocean at the North Pole
what might be a reason why a number of ships and airplanes get lost in the Bermuda Triangle?
methane "mega bursts", where giant bubbles of methane are released from the seafloor and suck down unfortunate vessels
where on earth are temperatures highest?
near the equator
fresh water is electrically ________________
neutral (nonconductive)
salinity is the strongest influence on density in _______________ oceans
polar - minimal vertical temperature variations in polar oceans make salinity the most important control on density there
climate on earth is closely related to what 2 things?
precipitation and salinity levels
what is the total amount of solid material dissolved in water?
salinity (g/1000g)
at low temperatures, the influence of ________________ is greater than the influence of ________________ in controlling density
salinity; temperature
temperature is more likely to change in shallow or deep water mass?
shallow
what is the second largest dissolved material in salt water?
sodium (cation = positive charge)
the hydrologic cycle is driven by what kind of energy?
solar
what is ultimately responsible for both atmospheric and oceanic circulation?
solar energy
what is the layer called of the ocean surface down to 200 meters water depth?
surface layer (wind mixed layer) - wind causes the waters to mix together, relatively uniform conditions
latitude controls what?
temperature
what does a TSD diagram show?
temperature-salinity-density shows combined influences of temperature and salinity on seawater density
what does stratification describe?
the layering of oceanic water masses, which are predominantly thin and laterally extensive (very thin pancakes)
the ocean is perfectly "density stratified", what does this mean?
the least dense water masses are on the surface, the densest water masses are on the bottom, and there is a density continuum from top to bottom
what is the hydrologic cycle?
the movement of water over the earth's surface
there is high salinity in what two tropics?
tropic of cancer tropic of capricorn - also the driest zones, P < E (precipitation < evaporation)
temperature is the strongest influence on density in _______________ oceans
tropical - large vertical temperature variations in tropical oceans make temperature the most important control on density
surface ocean salinity is ______________, while deeper ocean salinity is nearly the _________________
variable; same
evaporation tends to be weaker at what side of ocean basins?
west side - where warm poleward-flowing currents are located
is saline water conductive?
yes - conductivity is proportional to salinity, hence salinity can be calculated from conductivity
what is total deep water salinity variation?
~0.5 ppt (about 1/10 of surface waters)
what do oceanographers most commonly use to measure density?
σT - sigma t σT = X - 1000