water chemistry ocean currents wind gyres upwelling/ downwelling waves tides
DESCRIPTION
Water Chemistry Ocean Currents Wind Gyres Upwelling/ Downwelling Waves Tides. Water. Has semi-charged nature Good solvent Combines with other ions (Na + , Cl - , Ca +2 , Mg -2 , H + , HCO 3 - , CO 3 -2 High specific heat (long time to heat up, long time to cool down). - PowerPoint PPT PresentationTRANSCRIPT
WaterChemistryOcean CurrentsWindGyresUpwelling/DownwellingWavesTides
Has semi-charged natureGood solventCombines with other ions (Na+, Cl-, Ca+2, Mg-2,
H+ , HCO3-, CO3
-2 High specific heat (long time to heat up, long time to cool down)
Sea Water: Salinity related to dissolved salts, not just NaCl. Measured optically (refractometer) refraction salinity
chemically (chlorinity: just Cl- ) electrically (conductivity; more accurate than chlorinity)
Typical units= ppt= parts per thousand=gm dissolved salts /kg sea water Open ocean water ranges from 33-38 0/00
Water
Salinity
EvaporationIce formation
Rain fallF.W. input from rivers (etc)
Ionic Composition of major ionic components of seawater is nearly constant:Cl-
SO4-
Na+ Marcet’s PrincipleMg-2
Ca+2
etc.
Average time a constituent stays in sea water (residence time) is very highrelative to the average time to evenly mix the constituent in the ocean.
This is true for the open ocean, but varies as one gets closer to a coast.
Bahama Bank; 40 ppt
Salinity varies with Latitude
Temperature
Total Range: -1.9 – 40 o COpen Ocean: -1.9 – 27 o C
Deep (>1000 m) tropical oceans : 2-4 oC
Coryphaenoides acrolepis,
Rattail fish; MontereyCanyon, CA
pH Open water average approx. 8
Relevant Chemistry
CO2 + H2O H2CO3
H2CO3H+ + HCO3
-
HCO3- H+ + CO3
-2
Ca+2 + CO3-2 CaCO3
Carbon dioxide & Water Carbonic acid
Bicarbonate ion
Carbonate ion
Calcification
Calcium carbonate; foundation of Limestone; corals etc.
Calcium
(recall photosynthesis & cellular respiration)
Levinton 1982 (23-25oC for coral REEFS)
Calcification w/r/t temperature
http://www.springerlink.com/content/l63421782p60jh88/ (15-19oC is threshold)
Optimum rate of calcification in warm water
Ocean Currents
Coriolis Effect: Turntable visualizationEquator rotates at about 1700 km/hr
30oN, 30oS Latitude rotates at about1500 km/hr
60oN, 60oS Latitude rotates at about 800 km/hr
Coriolis Effect Sine (latitude)
CE
0 0.030 0.560 0.8690 1.0
WindWind drags sheets of water along the surface.
Velocity of the surface is 0.02 Velocity of wind (rule of thumb)
Surface sheet pulls on “sheets” below it, to a lesser and lesser extent
Wind effects can be detected down to 100 m
Stoke’s Drift: the wave-generated movement of a particle suspended in water
Wind
100 m
1. Surface water is deflected 45 deg. from direction of the wind due to Coriolis Effect
2. Surface water drags layer below it in the same direction, but at a slower speed. The slower speed shortens the length of the vector ( ), the Coriolis Effect deflects the direction of the vector.
Surface layer
100-150 m
At depth, water can move in opposite direction to the wind !!!
Wind
This model is known as the Ekman spiral, named for the Swedish physicist V Walfrid Ekman (1874-1954) who first described it mathematically in 1905. Ekman based his model on observations made by the Norwegian explorer Fridtjof Nansen (1861-1930).
http://oceanmotion.org/html/background/ocean-in-motion.htm
Langmuir Circulation
Gyres
Caused by Coriolis Effect: Pushes water to center of gyre. Sea surface can be 2mhigher in center of gyre than on periphery.
2m
Water flows down slope of lens= gravity flow
Geostrophic flow= balance between Coriolis flow to center and gravity flow to periphery
Can concentrate floatable garbage
“Earth”, “Twist; twisted cord”
Where does it rain the most?
Where the sun shines the most!
TropopauseHeight
North South
LowHIgh High
Warm moist air rising
ITCZSubtropical High Subtropical High
Northeast Trade Winds
Southeast Trade Winds
Doldrums Horse latitudesHorse latitudes
Hadley Cell Hadley Cell
Tropical Rainforests Deserts Deserts
Cold dry air descending
ITCZ
Tropic ofCancer
23.5 o
N latitudeTrade winds
Westerlies
North Pole
South Pole
Intertropical Convergence Zone – low pressure
Subtropical High Pressure
Subtropical High Pressure
Polar Front – low pressure
Polar Front – low pressure
Polar High Pressure
Polar High Pressure
Polar easterlies
Surface westerlies
Northeast trade winds
Southeast trade winds
Surface westerlies
Polar easterlies
-
45
60
23.5
0
90
30: Deserts
Upwelling
Density Gradient
Downwelling
Waves
λ
Direction of movement
T= period; time it takes for one λ to pass a point (sec/crest)
H= height
H
Frequency (f)= crests/secPeriod = sec/crest = ( 1/f)
Velocity = M/sec= wavelength/period=λ/T
Substituting: Velocity = λ/1/f or
Velocity = λf
Waves move ashore at V=λf
The waves reach shallower water and the rotating circles of water begin hitting the bottom.The bottom slows down relative to the surface and λ gets smaller. The “frequency push” fromocean remains constant, but there is now resistance from the bottom. …..Leads to Refraction.
Since λ DECLINES and f stays at least the same…….V must decline V=λf
Typical ocean waves can travel at approx 55.8 mph (90 km/hr)Tsunami waves travel at 589 mph (950 km/hr)
Refraction: Change(∆) in direction of a wave at a boundary between two media.
Depth change acts like a media change
Tides
The moon orbits the earth 50 min slower than the earth rotates around it’s axis
View from North
Sun, Earth, Moon
http://library.thinkquest.org/29033/begin/earthsunmoon.htm
Moon rotates around earth every 27.32 days
It orbits between 28.5 N Lat. and 28.5 S Lat.
The moon rises about 50 min. later each day
12 12:50 1:40 2:30
Thursday Wednesday Tuesday
Monday
At midnight
Do student demo
Gravitational Pull
Centrifugal Force
Timing of tide is based on orbital expectations of Sun & Moon
Transit time of tidal bulge is modified by ocean depth and basinshape (morphology)
Shallow, narrow basins SLOW the tide.
Therefore,
Timing can be different compared to expectations.
Eg. Bay of Fundy (NB, NS, Canada, Gulf of California, Bristol Channel (UK)
noon midnight noon noon midnight noon
High High High High High
Low Low Low
Semidiurnal Mixed Diurnal“partial daily” “daily”
http://www.pol.ac.uk/ntslf/pdf/Tortola_2010_+0400.pdf
Tide Predictions found at:
Questions
How do we incorporate this into our research?