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The ocean basins are divided into three main Oceans:

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The ocean basins are divided into three main Oceans: The Pacific Ocean is the largest and deepest (52% of the ocean area, mean depth of 4028 meters); – PowerPoint PPT presentation

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Title: The ocean basins are divided into three main Oceans:


1
  • The ocean basins are divided into three main
    Oceans
  • The Pacific Ocean is the largest and deepest (52
    of the ocean area, mean depth of 4028 meters)
  • The Indian Ocean (20 area, mean depth of 3897 m)
    and
  • The Atlantic Ocean, the shallowest because of the
    rather narrow deep basins (25 area, mean depth
    of 3332 m).
  • The Arctic is considered part of the Atlantic
    Ocean
  • The southern parts of the three Oceans are
    referred to as the Southern Ocean.
  • The northern hemisphere has less ocean than the
    southern hemisphere, only about 61 ocean versus
    81 for the southern hemisphere.

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Freshwater how strange!
Polar molecule hydrogen bonding
Water- a rather light molecule with strong bonds
5
How much would sea level in a 4000 m freshwater
ocean, fall if the 2 and 6C reservoirs r
0.9998 were to mix completely to form a 4C
reservoir r 1.000? Answer about 80 cm
Column 1 r0.9998
Column 2 r1.000
cabelling
Consequence Easy to freeze a lake
4
2C
6C
Balance beam
3
5
gravity
Weights are the same gr1h1gr2h2
sinking
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Q rCp Vol dT 1 watt 1
joule/sec 1 cal 4.184 joules If V 1 m3
and dT is 1C Qair (1.293)(1004) 1,298
joules Qwater (1023)(4218) 4,315,014 joules
over 3000 times larger than air So a little
change of water temperature balanced by sea-air
heat flux can really jolt the atmosphere. Same
true if water phase change is linked to
atmosphere temperature. You can play with the
numbers.
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Gulf Stream
Upwelling of cool subsurface water
Hot Warm-Pool
Cold, polar
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  • Sea water is about a 3.49 salt solution 34.9
    ppt, the rest is freshwater.
  • The major salt constituent is Chloride 55 and
    sodium 30.6
  • How salt alters the water properties

Is water colder than -2C observed? Yes, at the
base of glacial ice shelves of Antarctica. melts
at seawater Tf, why not 0C?
13
Ocean Salinity
  • Sea water is about a 3.49 salt solution 34.9
    ppt, the rest is freshwater.
  • The major salt constituent is Chloride 55 and
    sodium 30.6

1022 kg/m3
isopycnals
  • The more saline, the denser the sea water
  • Density of sea water is a function of temperature
    and salinity, both play an important role

1029 kg/m3
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atmosphere
A
B
ocean
A
EgtP
PgtE
B
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Stratification
  • Waters warmer than 10C dominate the sea surface
    but do not extend much below 500 m in the ocean
    the warm waters provide just a veneer of warmth
    over a cold ocean. The sharp drop off in
    temperature with depth is called the thermocline.
    Deeper cold waters derive their properties at the
    sea surface during winter at high latitude.

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Normal SST
El Niño
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Ocean Stratification Take away ideas 1.
Water Climate The ocean extends over 70.8 of
the earth's surface. The ocean holds 98 of the
1.4 billion cubic kilometers of water on the
planet, divided within three major basins. The
high capacity and density of water relative to
the atmosphere, and the great amount of energy
required for change of phase of water (solid -
liquid - vapor) makes the ocean a powerful and
stabilizing force of the Earth's climate system.
One obvious consequence of the oceans influence
is the marine effect, which acts to attenuate
winter/summer and day/night extremes of air
temperature. Another is that the ocean
circulation transfers significant amount of heat
from low to higher latitudes, helping the climate
system to attain an approximate steady state
condition. The ocean is a key part of the global
hydrological cycle, providing moisture for the
atmosphere ocean circulation of freshwater
balances the net evaporative and precipitation
belts. 2. Sea Surface Temperature The
temperature of the sea surface is high (27-30C)
near the equator, often the maximum value is
occurs a few degrees of latitude north of the
equator and low (at the sea water freezing point
of 1.9C) within the polar oceans. However,
there are also changes of sea surface temperature
with longitude. Warmer water projects poleward
along the western boundaries of the ocean. The
eastern tropical regions of each ocean are cooler
than the western tropical margin. These are due
to the movement of seawater in the horizontal
(ocean currents) and vertical (upwelling/sinking)
directions. Temperature and density of ocean
water are related inversely warm water means low
density, cold water means denser seawater. The
salt content of the water also affects Ocean
density.
30
3. Sea Surface Salinity Sea water is about
a 3.49 salt solution, the rest is freshwater.
The more saline, the denser the seawater. As the
range of salt concentration in the ocean varies
from about 3.2 to 3.8, oceanographers refer to
salt content as 'salinity', express salt
concentration as parts per thousand 34.9 ppt is
the average salinity. As seawater evaporates the
salt remains behind, only the freshwater is
transferred from the ocean to the atmosphere. A
region of excess evaporation, such as the
subtropics tends to become salty, while the areas
of excess rainfall become fresher. Sea ice
formation also removes freshwater from the ocean,
leaving behind a more saline solution. Along the
shores of Antarctica this process produces dense
water. Salinity reflects the workings of the
hydrological cycle the movement of freshwater
through the earth/ocean/atmosphere system.
4. Below the Sea Surface Waters warmer than
10C dominate the sea surface but do not extend
much below 500 m within the ocean tropical and
subtropical surface water provide is just a
veneer of warmth over a cold ocean typical deep
ocean temperature vary from 1 to 3C. The sharp
drop off in temperature with depth is called the
thermocline. The warm surface water is generally
saltier than the cooler deep or polar waters. The
halocline marks the drop of salinity with depth
that accompanies the thermocline. The surface
water warmth overrides the saltiness in governing
density, so that the warm surface water regions
coincide with buoyant (less dense) water. In
polar regions buoyancy of the surface layer is
mainly a consequence of the freshness of the
surface water. Deep cold waters derive their
properties at the sea surface during winter at
high latitude.
31
5. Deep Water Masses The deep Atlantic is
relatively salty (34.9). This water is derived
from the sinking of chilled saline surface water
in the northern North Atlantic. The cooling makes
the surface water dense, forcing it to sink, or
convect into the deep ocean, and spread southward
at depth. It is called North Atlantic Deep Water
(NADW). In contrast the deep Pacific is lower in
salinity (34.7), as it experiences no deep
convection of cooled salty surface water, its
surface layer is too fresh and buoyant to sink.
Pacific deep water is derived from the lower
salinity water column of the southern ocean.
Towards the sea floor, temperatures are near 0C
marking the presence of Antarctic Bottom Water
(AABW) derived from the very cold (-1.9C
34.65)), dense water along the shores of
Antarctica. At the base of the thermocline is the
low salinity Antarctic Intermediate Water (AAIW)
derived from sinking of cool (3 to 4C), low
salinity waters (34.4) from 50- 60S marking the
Antarctic Circumpolar Current and ocean polar
front zone.
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