pco 2009- 10 physical chemical oceanography
TRANSCRIPT
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
1/94
Oceanography
Greek word- Oceanus+ graphos meansdescription of oceans. It is scientificinvestigations, exploration and exploitation of
seafood, minerals and energy Oceanography is the scientific study of the
ocean. It is not a single science. There is fourparts viz. Chemical, biological, physical andgeological. Ocean engineering and marinepolicy is also included
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
2/94
Oceanography
Chemical oceanography is concerned withchemical reactions that occur both in theocean and on the sea floor
Bio. Ocean. Involves the study of distribution and environmental aspects oflife
Physical reactions, such as changes andmotion of sea water are comes under physical oceanography
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
3/94
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
4/94
Why study of ocean
Hostile and not readily accessibleenvironment that does not easily yield its
secrets Ocean is source of many commerciallyvaluable chemicals
Record of geological and biological history
Important food
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
5/94
FATHER OF OCEANOGRAPHY
Lt Mathew Fontaine Maury is often calledthe father of oceanography
Maurys maps of ocean currents, seasurface temperature and surface winds areamong his greatest accomplishments
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
6/94
Ocean basin
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
7/94
Ocean basin
Ocean basins can be described as saucer likedepressions of the sea bed
They vary in size from relatively minor features
of the continental margin to vast structuraldivisions of the deep ocean The largest ocean basins are 3 to 5 km deep
and stretch from the outer margins of the
continents to the mid ocean ridges Ocean basins cover approximately 71% of theEarths surface or about 361 m km2
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
8/94
Ocean basin
Their depth is 5000 m and the total volume isabout 1.35 billion km3
There are five major sub divisions of the world
ocean: the Pacific, the Atlantic, the Indian, theSouthern and the Arctic ocean The Pacific, the Atlantic and the Indian oceans
are conventional ocean basins and are bounded
by the continental masses or by ocean ridgesand currents; they merge below 400 Southlatitude in Antarctic circumpolar current, or westwind drift, at the Southern ocean
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
9/94
Pacific ocean basin
The pacific ocean basin is bounded on theeast by the North and South Americancontinents; on the north by the Bering
Strait; on the west by Asia, the MalayArchipelago, and Australia; and on thesouth by the Southern ocean
It is by far the largest and deepest of theworlds oceans and contains more thanhalf of its free water
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
10/94
Pacific ocean basin
The pacific is the oldest of the existing oceanbasins, its oldest rocks having been dated atabout 200 m years
The major features of the basin have beenshaped by the phenomenon associated withplate tectonics
The coastal shelf, which extends to depths of
about 180 m, is narrow along North and SouthAmerica, but is relatively wide along Asia andAustralia
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
11/94
Pacific ocean basin
The east Pacific rise, a mid ocean ridge, extendsfrom the Gulf of California to a point west of thesouthern tip of South America, and rises anaverage of 2130 m above the ocean floor
Along the East Pacific rise, molten rock up wellsfrom earths mantle, adding crust to the plateson each side of the rise. Due to that the oceanplates forced downward, farming deep trenches
called subduction zone The stresses at these areas of subduction areresponsible for the earthquakes and volcanoesthat the Pacific basin the name ring of fire
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
12/94
Atlantic ocean basin
Second largest ocean basin, the most heavilytraveled, and the most intensely studied,principally because of its importance in the ship
traffic between Europe and North America Occupies 20% of Earths surface, representing
approximately 75 m km2 , this includes itsmarginal seas; Baltic, Black, Caribbean, Davisstrait, Denmark strait, Gulf of Mexico,Mediterranean sea, North sea, Norwegian sea,and almost all of the Scotia sea
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
13/94
Atlantic ocean basin
The Atlantic is divided into two nominal sections:North Atlantic and South Atlantic
The ocean is essentially an S- shaped north-
south channel, extending from Arctic ocean inthe North to Southern ocean in the south The Atlantic ocean has an average depth of
3926 m, the deepest point is Milwaukee deep in
the Puerto Rico Trench (8605 m below surface It began to form during the Jurassic period,about 150 m years ago
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
14/94
Atlantic ocean basin
Along the American, African and Europeancoasts, there are the continental shelvesof the Atlantic basin
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
15/94
Indian ocean basin
It is third largest of the five oceans Bounded on west by Africa, on North by Asia, on the
east by Australia and the Australian islands, and on thesouth by the Southern ocean
No natural boundary separates the Indian ocean fromthe Atlantic ocean, but a line about 4020 km long,connecting Cape Agulhas at the southern end ofAfricawith Antarctica
Total area is 68 m km2
, which includes its marginal seas;Adman sea, Arabian sea, Bay of Bengal, GreatAustralian Bight, Gulf of Aden, Gulf of Oman, PersianGulf, Red sea and Strait of Malacca
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
16/94
Indian ocean basin
The average depth of the basin is about4210 m, although the Java trench reachesa depth of over 7258 m
The Indian basin is also divided in half bythe mid Indian Ocean ridge
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
17/94
Southern ocean basin
It extends from the coast of Antarcticanorth to 600 South latitude
It is fourth largest ocean of the world Its area is 20 m km2 and includesAmundsen sea, Bellingshausen sea, Rosssea, Weddell sea
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
18/94
Arctic ocean basin
The smallest of Earths five ocean basin isthe Arctic
It extends from the North pole to theshores of Europe, Asia and North America
The surface waters of the Arctic oceanmingle with those of the Pacific ocean
through the Bering strait, by way of anarrow and a shallow channel The total water area is 14 m km2
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
19/94
Arctic ocean basin
Approximately one third of the Arcticocean is underlain by continental shelf,which includes a broad shelf north of
Eurasia and the narrower shelves ofNorthAmerica and Greenland
The average depth of the Arctic ocean isonly about 1500 m
The deepest point in the Arctic ocean is5450 m
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
20/94
Distribution of water and land
Area of earth surface is 510.1 m km2 Land area- 148.8 m km2 (29.2%)
Ocean area- 361.3 m km2 (70.8%)
The world ocean is a continuous water blanketover the earth adjacent to all of the continentsand islands and possesses a generally saltystructure
In the Northern Hemisphere, the world oceanoccupies 61% of the area and in the SouthernHemisphere, 81%
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
21/94
Distribution of water and land
In one hemisphere the land dominated and inone the water is dominated, water will appear tocover more than half of the area (53%)
The oceanic hemisphere takes up about 91% ofthe area
The land predominates only between latitudes of450 N and 700 N, and to the south from latitudes700 to south pole. Water predominates theremaining part of the Globe
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
22/94
Distribution of water and land
The shapes of the shorelines, bottom,relief, systems of oceanic currents, tides,atmospheric circulation and a number of
other criteria subdivide the world oceaninto Pacific, Atlantic, Indian, Arctic andSouthern ocean
On the surface of the earth, altitudes lessthan 1000 m and depths from 3000 up to6000 m are predominate
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
23/94
Distribution of water and land
The water cover of the earth has volume of 1389.5 mkm3 and 97.4% of this consists salt water. Of thisvolume, 96.5% is in the world ocean and 0.9% is in saltyunderground and lake waters
F
reshwater comprises only of 2.6% of the total volume ofthe hydrosphere World ocean contain s 1340.7 m km3 of water, making
up 1/ 800th of the total volume of the earth In the process of exchanging water with the atmosphere
and continents, world ocean annually producesatmospheric precipitation of about 458000 km3, bothrivers and ground water produce 48000 km3 of water
Evaporation from the surface of the ocean produces506000 km3
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
24/94
Temperature as a physicalenvironmental factor
Temp. is one of the most important factors in anaquatic environment
Radiation from the sun striking the earthssurface of virtually all the energy that heats theocean surface and warms the lower portion ofthe atmosphere
Part of this incoming solar radiation is within thevisible part of the spectrum and provides the
energy to the plants on land and in the ocean After passing into the surface of ocean, most ofthis energy is converted into heat, either raisingwater temperature or causing evaporation
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
25/94
Temperature as a physicalenvironmental factor
The spectrum of radiant energy from the sun isfiltered once as it passes through theatmosphere and further filtered in the surface
ocean Within first 10 cm of even pure water, virtually allthe infrared portion of the spectrum is absorbedand changed into heat
W
ithin the first meter, about 60% of the enteringradiation is absorbed, about 80% is absorbed inthe first 10 m, only 10% remains at 140 m inclearest subtropical ocean waters
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
26/94
Heat budget in ocean
Less than 20% of the solar radiation reachingEarth is absorbed by atmospheric gases andclouds, 50% is absorbed by earths surface
mostly the ocean and 31% is reflected back tothe space
The oceans effectively capture a major portion(about 50%) of the suns radiated energy and
transfer much of it to the atmosphere as latentheat of vaporization and as radiation
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
27/94
Sources of heat in ocean
Solar energy- it is about 300 watt/m2
Geologic source
Heat generated by the radioactive decay ofelements within earth (about 0.1 micro watt/m2)
Heat left over from earths formation
Human induced through burning of fossilfuels (3 milli watt/ m2)
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
28/94
Output of heat
The evaporation/ precipitation cycle is animportant part of the heat energy releasedinto the atmosphere
About 2/3 is evaporated and 1/3 isradiated
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
29/94
Temperature distribution in ocean
Max. amount of incoming solar radiation isreceived in low latitudes (the earth receives mostof its heat between 400 N & 400 S, where as
there is a net loss to space in the high latitudesbetween 400 & 900 in both the hemispheres The temperature difference between warmest
and coldest month of the year is small < 30C inlow latitudes (100 N to 100 S)
When sun is over head only 2% of incomingradiation is reflected
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
30/94
Temperature distribution in ocean
The fall in temperature with increase in depth,results into the increase of density, which givesvital vertical stability to maintain water masses in
the ocean Temperature difference is very limited sincethere is continuous circulation of the water
Surface water has some effect of atmosphere
and reduce with the depth in deep sea temp.constant at 40 C. Deep water temp. is 00 C nearAntarctic and 2- 4 0 C towards the equator
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
31/94
Temperature distribution in ocean
The surface water of low latitudes, thetemperature is mostly ranging between 26to 300 C. Surface temperature maybecome as high as 350 C in the Persiangulf. In some of the tropical lagoons andintertidal rock pools the temperature may
rise to even 500 C in summers
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
32/94
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
33/94
Thermocline
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
34/94
Thermocline
The thermocline (sometimesmetalimnion) is a layer within a body of water or air where the temperature
changes rapidly with depth Below this layer however, the temperature
drops very rapidlyperhaps as much as200 C with an additional 150 m of depth
In the ocean 90% of the water is belowthermocline (consist of equal density)
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
35/94
Thermocline
Varies with latitude and season. It is permanent intropics, variable in temperate and weak to nonexistent inpolar region
PT formed at depth from 100- 500 m due to equator
ward flow of deep coldwater from poles and the poleward flow of warm water from the surface of equator
Temporary derived mainly due to change in temperatureand it is not stable, formed at the depth of 100 to 150 m
Diurnal- formed very near to the surface (about 10 mdepth) during day and governed by difference in temp.due to diurnal effect
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
36/94
Density of sea water
Determined primarily by temperature and salinity Decreases with temperature and increases with
salinity
Changing salinity from 19 to 26 ppt at constanttemp. (30 0 C) has the same effect as changingthe temp. from 31 to 12 0 C at constant salinity(20 pot)
Vertically stratified due to change in salinity Densest water at bottom Neutrally stable system when density is same
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
37/94
Density of sea water
In coastal waters, mixing is commonbecause tidal currents and movement ofwaters
Three general depth zones according todensity i.e. surface, pycnocline and deepzone are formed
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
38/94
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
39/94
Tolerance to temperature variation
Stenothermal Tolerate only slight
variation of
temperature
Internal bodytemperature fluctuate
Example- marineinvertebrates, marine
fishes, reptiles
Eurythermal Tolerate a wide range
of temperature
Have temperatureregulating mechanism
Example- sea birds,sea mammals,
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
40/94
Marine invertebrates and fishes
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
41/94
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
42/94
Temperature and distribution oforganism
No strict and well defined barriers in theoceans
Controlled by latitudes and depth of water Surface water has three groups viz. warm(> 18 0C), cold (< 5 0C) and temperate (5-18 0C) waters
Temperature influence physiological andmetabolic processes directly
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
43/94
Salinity
Most characteristic feature of sea. Deals withdensity and specific gravity of water
Most of the elements occurring on earth, are
encountered in oceanic water About 84 elements are so for known to makingsea water but only 6 (Chlorine, sodium,magnesium, sulphate, potassium and calcium)
are common Important compounds are MgCl2, MgBr2,MgSO4, CaCO3, CaSO4, K2SO4 and NaCl
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
44/94
Salinity
The existence of trace elements viz. Co,Ni, Cd etc. are revealed from many marineplants and organisms which are able to
concentrate Sulpher bacteria- sulpher Radiolarians- silica and strontium
Molluscs- Nickel Lobsters and mussels- cobalt
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
45/94
Salinity
Algae and sponges- Iodine
Certain sea weeds(Gracilaria and
Sargassum)-A
luminium Jelly fishes- Zn, Tin and Pb
Crustacians and molluscs- copper inhaemocyanin
Blood of ascidians and holothurians-vanadium
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
46/94
Salinity
Calcium is needed by molluscs, corals formaking their shells
Silica is utilized by diatoms andradiolarians for their glossy cells
Presence can be detected by analysingash of marine organism
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
47/94
Origin of elements
Majority are introduce through cosmicsources (water is best solvent)
Others are introduced through landdrainage
Chemical elements are found to bedeposited at the ocean floor through thedead decay of the marine organism andtheir fresh supply from river drainage
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
48/94
Major chemical constituents ofocean
Chloride- 19.353 g
Sulphate- 2.511
Bicarbonate- 0.142
Trace- 0.181
Sodium- 10.76 g
Magnesium- 1.287 g
Calcium- 0.41 g
Strontium- 0.0077
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
49/94
Salinity definition
In 1902, there was an establishment ofInternational Commission headed by Fork,Knudson, and Sorenson, to define the
salinity Salinity is an account of water or a
measure of dissolved solids in grams in
one kg of sea water when all carbonatesare oxidized, Bromine and iodine arereplaced as chloride and all organic mattercompletely oxidized
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
50/94
Salinity
Salinity is measured in the form ofchlorinity
Chlorinity can be measured by titrating sea
water with AgNO3 using potassiumchromate as indicator
The empirical relationship between salinity
and chlorinity isSalinity (ppt) = 0.03+ (1.805x chlorinity) Here other halides are ignored
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
51/94
Salinity
The above relationship between salinity andchlorinity is no longer strictly true
For improvement, the International Commissiondecided to prepare a primary standard of known
chlorinity called as normal water and task wasgiven to Hydrographical laboratory,Copenhagen, Denmark
Accordingly 19.4 pot normal water was prepared
and a table was prepared byW
oodsW
holeOceanographic Institution, Masachussats,USAconsisting of relation of salinity, chlorinity andnormal water
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
52/94
Factors affecting salinity
Evaporation and precipitation are two mainfactors which affect salinity very much
It vary in fixed rate (does not go a widefluctuations)
The salinity change due to mixing processresulted due to horizontal and vertical currents
It can be estimated by S= So + K (E- P) Where S is salinity of surface water, So is
salinity change due to mixing process, E is rateof evaporation, P is rate of precipitation and K isconstant
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
53/94
Evaporation and precipitation
Total evaporation from earth is 334000 Km3/ yr Out of which 297000 Km3/ yr is the precipitation
received by the ocean directly in a year time
The remaining 37000 Km3
/ yr is supplied by land runoff.
If any change in this ratio, the salinity changedrastically
The average precipitation , falling on the year time is99000 Km3/ yr out of which 37000 Km3/ yr comesthrough ocean evaporation and 62000 Km3/ yr issupplied through evaporation of inland resources
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
54/94
Conditions required for evaporation
If oceanic surface is warmer than the overlyingair evaporation always takes place
The vapour pressure initially remains greater at
the sea surface than that in the air The evaporation greatly facilitated in such
conditions because the turbulence of air will
developed fully owing to unstable stratificationof very lowest layer of atmosphere
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
55/94
Conditions required for evaporation
In such conditions, the heat is transferred from warmsurface water to the overlying air till the lowest layer ofatmosphere gets laden with moisture equal to thesurface water
If the air is much colder, it gets rapidly saturated withwater vapour and thus fog or mist is form over thewater surface and when wind blows it carried upwards
The evaporation process can be observed morekeenly near the coast but not over open oceanbecause the necessary temperature gradientdifferences are rapidly eliminated as the distance
increases
Conditions required for advection
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
56/94
Conditions required for advectionfog
When the sea surface is colder than overlying air,advection fog is formed
Here water vapour is rarely produced and air does notgets saturated with moisture
The direction of heat transfer is reversed here andcondensation takes place in such a way that the heatis brought to the surface oceanic water and heatcarried away from it
The turbulence in the air is greatly reduced and theheat transfer would stop only when vapour content oflowest layer of atmosphere has reached the valueequivalent to heat of vapour pressure at the sea
surface
Salinity of different oceans up to
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
57/94
Salinity of different oceans up tothe depth of 400- 600 m
Mid Pacific- 35.5 ppt Mid Atlantic- 37.0 ppt North Pacific- 33.7 ppt North Atlantic- 35.3 pot
Red sea- 40.0 pot Inshore waters of Bahamas 155.0 ppt
and West Indies (due to less depth and its enclosedgeographic structure)
Baltic sea 8.0 to 0.0 ppt Gulf of Bothnia (due to narrow
connection with Atlanticocean and North sea)- 8.0 to 0.0 ppt
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
58/94
Salinity changes at different latitudeand longitude
Salinity varies place to place due to change inaverage evaporation and precipitation rates atdifferent latitude and longitude
Evaporation changes due to change in solar
radiation at different latitudes Surface water salinity is minimum at equator
because the rate the rate of precipitation is morethan the evaporation
The surface water salinity is maximum in theworld oceans between 20 0 N and 20 0 Sbecause in this part evaporation is more thanthat of precipitation
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
59/94
Salinity changes at different latitudeand longitude
In temperate region, the melting of icewater get stagnated in the basin there byreducing salinity
At higher latitude the average salinity ismuch lesser
In Indian subcontinent, there is seasonal
fluctuation owing to influence of monsoon,evaporation, precipitation and riverdischarge
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
60/94
Salinity changes at different latitudeand longitude
The salinity ofArabian sea and Bay ofBengal is between 36.0 to 36.5 ppt and33.0 to 34.0 ppt
Arabian sea is connected to most aridseas like Red sea and Parsian Gulf
Bay of Bengal receives river discharge
from most of the Indian rivers.
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
61/94
Types of waves
Wind generating waves- formed due tosea surface due to transfer of energy fromair to the sea surface and resultant
pressure fluctuations create vibration overwater surface to form waves duringturbulent wind conditions
Internal waves- Indirect effect of
atmosphere, formed by bring intointeraction of water of different densitiesand thermal gradients together
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
62/94
Types of waves
Catastrophic waves- in the form of stormsurges and tidal currents, atmospheric andcosmic influences are also responsible for
creation of such waves
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
63/94
Ocean waves
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
64/94
Wave crest and trough
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
65/94
Waves
Wave length- The horizontal distance betweentwo successive crest or trough (L)
The time required for two successive crests or
two successive troughs to pass a fixed point inspace is called the period T
Wave height (H) is the vertical distance
between crest and succeeding trough
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
66/94
Waves
Steepness is the wave height divided bythe wave length (H/L)- when wavesteepness exceeds 1/7, wave become
unstable and begin to break by raveling ofover steepened crests
The angle at the crest must be 1200 or
greater for the wave to remain stable
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
67/94
Characteristic of wave
A wave transfers a disturbance from onepart of a material to another
The disturbance is propagated through the
material without any substantial overallmotion of material itself
The disturbance is propagated without anysignificant distortion of the wave form
The disturbance appears to be propagatedwith constant speed
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
68/94
Characteristic of wave
When small waves move through deep water,individual bits of water move in circular orbitswhich are vertical and nearly closed
The water moves forward as crest passes, thenvertically, and finally backward as the troughpasses
After each wave has passed, the water parcel isfound nearly in its original position but there issome slight net movement of the water
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
69/94
Wave forms
All waves are progressive waves Body waves travel through materials Surface waves occur at the interface
between two bodies of fluid (capillary andgravity waves)
Sine waves- crest and trough tend to be
rounded and may be approximated Trochoid waves- crest is more sharplypointed
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
70/94
Deep water waves
In the deeper water where depth is greaterthan L/2, water parcel move in nearlystationary circular orbits, are known as deep
water waves. The diameter is equal to waveheight. It decreases to one- half the waveheight at a depth of L/9 and is nearly 0 at
the depth of L/2
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
71/94
Formation of waves
Involve two forces- disturbance and stillwater
Disturbing waves are wind generatingwaves, tides, tsunamis etc. these arealso called as forced waves
Free waves move independently e.g.
explosion generated wave
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
72/94
Formation of waves
Once a wave has formed , restoring forces actto restore the equilibrium.
For smallest wave (L 1.7 cm, TP < 0.1 sec.) the
dominant restoring force is surface tension For waves with periods between 1 and 5 min.,
gravity is the restoring force
The waves whose period is more than 5 min.,gravity and coriolis forces are the restoringforces
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
73/94
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
74/94
TSUNAMI
These are long wavelength, shallow water progressivewaves caused by rapid displacement of ocean water
Displacement is caused by sudden vertical movementof the earth along a fault line, also by landslides,
iceberg falling and volcanic eruptions These are shallow and deep water waves (> of the
wavelength) Speed will be calculated as c= gd
When it reaches shore, its wavelength and velocitydecreases, increases wave height while period remainconstant
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
75/94
Currents
Large scale water movement occurring in the oceanand carrying the water everywhere in the ocean
Winds and unequal heating and cooling are two forces
for causing major currents It contribute to heat transfer from tropics to poles andfrom poles to tropic thereby partially equalizing earthsurface temperature
A
round equator, the surface water carry warm water tothe region of higher latitudes of both the hemisphererespectively
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
76/94
O i d ld t
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
77/94
Ocean wise warm and cold watercurrents
South Atlantic Warmwater currents
South equatorial currents bring warm water in Brazil
region as Brazil currents Brazil current brings warm water to Antarctic and
water return to the West Africa coast through Bengulacurrents
Coldwater currents From Antarctic region, the Falkland current and West
wind drift to lower latitude
O i d ld t
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
78/94
Ocean wise warm and cold watercurrents
North Pacific Warm water currents
North Pacific current to higher latitude and surplus
water as California current Through Kuroshio current from Japan region,
warm water to higher latitude
Cold water currents
Oyashio, Sub Arctic and Alaska currents fromArctic to low latitudes
O i d ld t
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
79/94
Ocean wise warm and cold watercurrents
South Pacific Warm water currents
South Equatorial currents, Peru currents and EastA
ustralian current Cold water currents West wind drift and West Australian currents
Seasonal currents ofNorth Indian region
During summer the continental Asia is greatlywarmed up, the continental air rises anddraws air from the ocean towards land
S l t f N th I di
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
80/94
Seasonal currents ofNorth Indianregion
The South West monsoon currentreplaces North Equatorial currents
In winter just reverse takes place. TheNorth Equatorial current reappear andmay cause cyclone
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
81/94
CO
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
82/94
CO2
Minor constituent of atmosphere and equilibriumconcentration in pure water is small Derived from the atmosphere, respiration of animals and
plants, bacterial decomposition of organic matter,inflowing ground waters which seep into the ponds, lakesand streams and from within the water itself in
combination with other substances Solubility of CO2 is 30 times that of oxygen. It dissolves
in water to produce H2CO3 which dissociates into variousfractions depending upon the pH
Solubility of CO2 is decreases with increase of
temperature 00 C- 1.1 mg/l 100 C- 0.76 mg/l 200 C- 0.56 mg/l 300 C- 0.42 mg/l
CO
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
83/94
CO2
Reduction of CO2 by photosynthesis, marlforming organism, agitation of water,evaporation and bubble formation
is not appreciably toxic to fish
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
84/94
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
85/94
P4 and N2 cycles in ocean
In shallow waters nutrients recycle fairly quickly Seasonal variation in phosphorus cycle During winter, when phytoplankton populations
are small, dissolved inorganic phosphorusconcentrations are as high as 0.002 mg/l or more
In spring, P4 level drop sharply. When nutrientlevel drop off, organisms die and release
nutrients or in some cases a zooplankton bloomresults from abundance of plant food and theanimals release nutrients during metabolism
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
86/94
P4 and N2 cycles in ocean
Dissolved and particulate organic phosphorusreleased by phytoplankton and animals isutilized by bacteria and certain heterotrophicphytoplankton
N2 cycle is more slowly because energy isrequired to fix it in organic form, reduce it, andfinally to oxidize it back to N2
Zooplankton facilitate this process by releasingsoluble organic N2 compounds such as ureaand NH3 which can be taken up byphytoplankton
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
87/94
Nitrogen
Occurs in combination with other elements suchas ammonia, nitrite and nitrate or free form
Vital for all organisms, helps to synthesizecomplex protein molecules that affect growthand reproduction
They regularly remove complex nitrogencompounds as excreta
On the death, complex nitrogenous compoundsdecomposed into simpler chemical compoundsby bacteria
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
88/94
Nitrogen
There are two forms of nitrogen elementalor uncombined and inorganic/ organiccompounds
Elemental nitrogen come from atmosphere Solubility of nitrogen varies with
temperature and super saturation causegas bubble disease
Inorganic nitrogen present in the form ofNH3, NO2 and NO3
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
89/94
Nitrogen
Organic nitrogen constitute about 50% oftotal. Most of it is composed as aminoacid, polypeptides and proteins
Process involve in N2 cycle arenitrification, denitrification andammonification
Nitrogen cycle
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
90/94
Nitrogen cycle
Phosphorus cycle
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
91/94
Phosphorus cycle
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
92/94
Silica
Occurs mainly as orthosilicate in anundissociated condition at the normallyencountered pH values
Most abundant in sedimentary rocks andtherefore, occurs generally in higher concentrations in such regions
Silica is utilized most by diatoms and amajor
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
93/94
Silica cycle
-
8/7/2019 PCO 2009- 10 physical chemical oceanography
94/94