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Water Chemistry Ocean Currents Wind Gyres Upwelling/ Downwelling Waves Tides PowerPoint PPT Presentation


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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).

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Water Chemistry Ocean Currents Wind Gyres Upwelling/ Downwelling Waves Tides

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Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Water

Chemistry

Ocean Currents

Wind

Gyres

Upwelling/Downwelling

Waves

Tides


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+ , 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 chemistry ocean currents wind gyres upwelling downwelling waves tides

Evaporation

Ice formation

Salinity

Rain fall

F.W. input from rivers (etc)


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Ionic Composition of major ionic components of seawater is nearly constant:

Cl-

SO4-

Na+Marcet’s Principle

Mg-2

Ca+2

etc.

This is true for the open ocean, but varies as one gets closer to a coast.

Average time a constituent stays in sea water (residence time) is very high

relative to the average time to evenly mix the constituent in the ocean.


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Salinity varies with Latitude

Bahama Bank; 40 ppt


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Temperature

Total Range: -1.9 – 40 o C

Open Ocean: -1.9 – 27 o C

Coryphaenoidesacrolepis,

Rattail fish; Monterey

Canyon, CA

Deep (>1000 m) tropical

oceans : 2-4 oC


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

pH Open water average approx. 8


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Relevant Chemistry

(recall photosynthesis & cellular respiration)

H2CO3

CO2 + H2O

Carbonic acid

Carbon dioxide & Water

H+ + HCO3-

H2CO3

Bicarbonate ion

HCO3-

H+ + CO3-2

Carbonate ion

Ca+2 + CO3-2

CaCO3

Calcium

Calcium carbonate; foundation of

Limestone; corals etc.

Calcification


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Calcification w/r/t temperature

Levinton 1982 (23-25oC for coral REEFS)

http://www.springerlink.com/content/l63421782p60jh88/ (15-19oC is threshold)

Optimum rate of calcification in warm water


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Ocean Currents

Coriolis Effect: Turntable visualization

Equator 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 0.0

0.5

0.86

90 1.0


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Wind

Wind 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


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

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.

Wind

Surface layer

100-150 m

At depth, water can move in opposite direction to the wind !!!


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

This model is known as the Ekman spiral, named for the Swedish physicist V WalfridEkman (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


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Langmuir Circulation


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Gyres

Caused by Coriolis Effect: Pushes water to center of gyre. Sea surface can be 2m

higher in center of gyre than on periphery.

Can concentrate floatable garbage

2m

Water flows down slope of lens= gravity flow

Geostrophic flow= balance between Coriolis flow to center and gravity flow to periphery

“Earth”, “Twist; twisted cord”


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Where does it rain the most?

Where the sun shines the most!


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Height

Tropopause

Warm moist

air rising

Hadley Cell

Hadley Cell

Cold dry air descending

HIgh

Low

High

North

Subtropical High

South

Subtropical High

ITCZ

Northeast Trade Winds

Doldrums

Southeast Trade Winds

Horse latitudes

Horse latitudes

Deserts

Tropical Rainforests

Deserts


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Tropic of

Cancer

Westerlies

23.5 o

N latitude

Trade winds

ITCZ


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

90

North Pole

60

Polar High Pressure

Polar easterlies

45

Polar Front – low pressure

30: Deserts

Surface westerlies

23.5

Subtropical High Pressure

Northeast trade winds

Intertropical Convergence Zone – low pressure

-

0

Southeast trade winds

Subtropical High Pressure

Surface westerlies

Polar Front – low pressure

Polar easterlies

Polar High Pressure

South Pole


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Upwelling

Density Gradient

Downwelling


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Waves

λ

Direction of

movement

H

T= period; time it takes for one

λ

to pass a point (sec/crest)

H= height


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Frequency (f)= crests/sec

Period = sec/crest = ( 1/f)

Velocity = M/sec= wavelength/period=λ/T

Substituting: Velocity = λ/1/f or

Velocity = λf


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Waves move ashore at V=λf


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

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” from

ocean remains constant, but there is now resistance from the bottom. …..Leads to Refraction.

SinceλDECLINES 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)


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Refraction: Change(∆) in direction of a wave at a boundary

between two media.

Depth change acts like a media change


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Tides

The moon orbits the earth 50 min slower than the earth rotates around it’s axis

View from North

Moon rotates around earth every 27.32 days

It orbits between 28.5 N Lat. and 28.5 S Lat.

Sun, Earth, Moon

http://library.thinkquest.org/29033/begin/earthsunmoon.htm


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

The moon rises about 50 min. later each day

12 12:50 1:40 2:30

At midnight

Thursday

Wednesday

Tuesday

Monday


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Gravitational Pull

Centrifugal Force

Do student demo


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Timing of tide is based on orbital expectations of Sun & Moon

Transit time of tidal bulge is modified by ocean depth and basin

shape (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)


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Tide Predictions found at:

http://www.pol.ac.uk/ntslf/pdf/Tortola_2010_+0400.pdf

High HighHighHighHigh

Low

Low Low

noon midnight noon noon midnight noon

Semidiurnal Mixed Diurnal

“partial daily” “daily”


Water chemistry ocean currents wind gyres upwelling downwelling waves tides

Questions

How do we incorporate this into our research?


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