Ocean

1. The Oceans
Zonal Classification

2. Why study major bodies of water?
• Water covers nearly ¾ of the earth’s
surface
• More than 50% of the world’s
population lives within an hour of the
coast
• Plays a role in both climate and day-to-
day weather
• FOOD!
– Cost of your food could depend on it

3. The “Basics”
There are FOUR oceans
• ATLANTIC
• PACIFIC
• INDIAN
• SOUTHERN

4. Around the World in 4 Slides…
Begins at 60°S
Mediterranean Sea
Arctic Sea
Gulf of Mexico
Caribbean Sea

5. Around the World in 4 Slides…
Begins at 60°S
Gulf of Alaska
Bering Sea
Sea of Japan

6. Around the World in 4 Slides…
Begins at 60° S
Red Sea
Persian Gulf
Arabian Sea

7. Ocean or Sea, What’s the Big Deal?
SEAS
• Delineated by land masses
– Doesn’t matter if they’re largely enclosed
• Also “communicate” with the ocean
Strait of Gibralter
Black Sea
Mediterranean Sea
Africa
Europe
Gulf of Mexico
United States
Mexico

8. Bragging Rights…
Which ocean is the biggest?
OCEAN SURFACE AREA [km2] OF ALL
OCEANS…
Atlantic 90,818,000 27.1%
Indian 68,556,000 20.4%
Pacific 155,557,000 46.4%
Southern 20,327,000 6.1%

9. Bragging Rights…
Which ocean has the most coastline?
OCEAN COASTLINE LENGTH [km]
Atlantic 111,866
Indian 66,526
Pacific 135,663
Southern 17,968

10. Water is Water…or is it?!
FRESHWATER
• Rivers
• Streams
• Lakes
SALTWATER
• Oceans
• Gulfs
• Seas

11. Water is Water…or is it?!
QUESTION:
Is saltwater the same everywhere?
ANSWER:
Nope.
In general, the Atlantic Ocean is the
“saltiest.”

12. Please Pass the Salt…
• “Run-of-the-mill” concentration?
– 3.5 grams/liter
• Like weather, there are areas of
– HIGH salinity
– LOW salinity
So, where are these “highs” and
“lows”?

13. Please Pass the Salt…
H
H
H
H
H
L
L
L

14. Mmmmm…Salty!
DEAD SEA FACTS:
• Really a large lake
• Water gets in, but not
out!
– Fed by River Jordan
– Evaporation only way
out
• Has nearly 10 times the
salinity of the oceans!
– Leads to increased
density
Dead Sea was named
because it had no life!

15. So??
The increased
density means
just about anything
will float!
We can see this through the use of eggs!

16. We’re Goin’ Down, Down, Down…
Just like the atmosphere, the
ocean has layers!

17. Ocean zones and continental margins
• Many ocean zones are defined based on continental
margins.
• To help you understand ocean zones, let’s first review
continental Margins:
• Continental Margin: Submerged area of continents.
Include:
– Continental Shelf (flat gradually sloping seafloor) from
shoreline to ~ 200m; End of Shelf is called the Shelf Break
– Continental Slope (steeply sloping seafloor) seaward of shelf
break
– Continental Rise (Moderately sloping seafloor) seaward of
slope
17

18. Pelagic and benthic zones
• One simple ocean zone
classification is between the
water and the ocean floor
• The water is referred to as the
pelagic zone
– Organisms that swim through the
water column are known as
nekton
• The ocean floor is referred to
as the benthic zone
– Organisms that live here are
benthic organisms or benthos
Photos: NOAA
Shark: Pelagic (nekton)
Crab: Benthic (benthos
18

19. Pelagic and benthic zone divisions
19
Pelagic zone divisions
(depth from surface)
Benthic zone divisions
(seafloor zones)
Supralittoral –shore above high tide
Epipelagic (0-200m) Littoral – the intertidal zone (sometimes
submerged and sometimes above water)
Mesopelagic (200-1,000m) Sublittoral – seafloor of the continental
shelf (from low tide to the shelf break)
Bathypelagic (1,000-4,000m) Bathyl – seafloor of the continental slope
to the deep ocean bottom
Abyssopelagic (4,000-6,000m Abyssal – deep ocean bottom between
the base of the slope and 6,000 m
Hadalpelagic (6,000-10,000m) Hadal – the deepest zone, below 6,000m

20. Pelagic and benthic zone divisions
20
Pelagic
zone
Littoral
200m
1,000m
4,000m
6,000m

22. The Epipelagic Zone
• “Sunlight Zone”
– Most solar heating
– Lots of temperature
change
• Surface to 200m
• Influenced by
wind

23. Bridge Over Troubled Waters…
• A transition layer
• Temperature
decreases rapidly
• Relevance to you?
– Higher bass
concentrations
(oxygen is just right)

24. The Mesopelagic Zone
• “Twilight Zone”
– Most temperature
change near top of
layer
• Between 200 and
1000m
• Animal
characteristics
begin to change

25. The Bathypelagic Zone
• “Midnight Zone”
– No light at all
– Only light comes
from animals
• Very little
temperature
change
• Pressure reaches
over 5800 p.s.i.

26. The Abyssopelagic Zone
• “The Abyss”
– Greek word
meaning “no
bottom”
• Between 4000
and 6000m
• Water
temperature near
freezing

27. The Hadalpelagic Zone
• “The Trenches”
• Anything below
6000m
• Worth repeating:
– Deepest trench is
the Mariana Trench
– “Weight”: >8 t.s.i.
• Life still exists
here!
That’s TONS per
square inch!

28. Our Mr. Sun
• “Driving Force”
• Solar radiation
affects the ocean
differently
– More on this later
• Ultimate cause of
wind

29. Ocean Currents – Just the Facts
• Two types:
– Wind-driven Currents
– Deep Water Currents
• 40% of the global heat transport
• Move slower than surface winds
– Kilometers per day vs. kilometers per hour
• Long-term climate impacts
– Gulf Stream most important in our region

30. Ocean Currents -- Development
• Oceans near
equator “heat up”
more than the poles
• Sets up…
– Temperature
imbalance
– Semi-permanent
pressure areas
– Constant push of
wind on water

31. Ocean Currents – The Big Picture

32. Dust in the Wind – During the Day
• Beach heats faster
than ocean
• Air rises onshore
• Slightly cooler,
denser air moves
onshore to replace
the “lost” air
• Results:
– Onshore breeze
– Possible storm
development

33. Dust in the Wind – At Night
• Beach cools faster
than ocean
• Air rises offshore
• Slightly cooler,
denser air moves
offshore to replace
the “lost” air
• Results:
– Offshore breeze
– Possible storm
development

34. Wave Action
• Another byproduct of wind
• Size depends on THREE things:
– Speed
– Duration
– Distance
• Longer the wave, the faster it moves
• Here’s a cool fact:
– You can estimate the wind speed using
the size of waves

35. Battle of the Bulge
• Tides are another
type of wave action
• Definition:
– A change in the
ocean water level,
which results from
the gravitational pull
of the moon

36. Battle of the Bulge
• Why the moon?
– Sun’s gravitational
pull is greater
– But the moon is
closer
• Mariners have
known for a long
time that tides were
related to the moon

37. Battle of the Bulge
• Famous dead
people who have
studied tidal motion:
– Galileo
– Descartes
– Newton
– Laplace
– Lord Kelvin
– Kepler

38. Two tides? Four tides?
• Number of tides per day related to…
– Shape of the coastline
– Sea floor elevation
• Some places have one high/low tide
cycle
– Called a diurnal tide
– Examples:
• Lake Charles, LA
• Gulfport, MS
• Gulf Shores, AL
• Pensacola, FL

39. Two tides? Four tides?
• Number of tides per day related to…
– Shape of the coastline
– Sea floor elevation
• Other places have two high/low tide
cycles
– Called a semi-diurnal tide
– Examples:
• Galveston, TX
• Apalachicola, FL

40. Largest Tidal Range in the World
Bay of Fundy!
High Tide Low Tide

41. The Knights Who Say “Neap”
• Occur when the pull
of the moon and
sun partially cancel
each other
• RESULT:
– Very little change
between high and
low tides

42. Springing Onward…
• Occurs when the
pull of the sun and
moon act together
• RESULT:
– Greater than normal
tidal range
experienced

43. About the Cost of Your Food…
• Normally…
– Warm waters over
Central Pacific
– Cooler waters off
Peruvian coast
• Colder, nutrient-rich
waters pulled up
from western coast
of South America

44. About the Cost of Your Food…
• El Nino:
– Equatorial
Countercurrent
strengthens
– Nutrient-rich water
supply lessens
• RESULT:
– Waters warm off
Peruvian Coast

45. About the Cost of Your Food…
• La Nina:
– Weaker Equatorial
Countercurrent
– Nutrient-rich water
supply increases
• RESULT:
– Warm waters “pile
up” in the western
Pacific