The Sea Around Us, Lecture 7, 4 Feb 2014 Ocean & Atmospheric Circulation, It’s all about HEAT Here...
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The Sea Around Us, Lecture 7, 4 Feb 2014 Ocean & Atmospheric Circulation, It’s all about HEAT Here Comes the Sun! Around the Sun, REM Under the Sea Timeflies
The Sea Around Us, Lecture 7, 4 Feb 2014 Ocean &
Atmospheric Circulation, Its all about HEAT Here Comes the Sun!
Around the Sun, REM Under the Sea Timeflies Tuesday Thanks to
Victor T. A drop in the ocean Ron Pope Thanks to Meryem B.
Slide 3
Read: Chap. 6 & 7 Course web site, Lecture Notes linkCourse
web site OLA3 Due Today! Quiz 1, Friday Feb 7 Thanks to Michelle W.
and Emma W. No Lecture on Thurs. Feb 6 (TAs will be here, 100
Thomas, to answer questions)
Slide 4
What drives atmospheric and ocean Circulation? Lets examine how
the spatial distribution of energy receipt and how the resulting
temperature gradient drives ocean and atmospheric convection Well
see how the winds (atmospheric circulation) drives circulation of
ocean Surface Water! Lets examine how the spatial distribution of
energy receipt and how the resulting temperature gradient drives
ocean and atmospheric convection Well see how the winds
(atmospheric circulation) drives circulation of ocean Surface
Water!
Slide 5
Slide 6
Global "Thermohaline" Circulation Circulation of ocean water
driven by temperature and salinity differences
Slide 7
The Ocean "Conveyor Belt" The "Conveyor" system is a very
generalized view of the work done by surface and deep circulation
in mass and heat transfer. Sinking of cold dense waters at high
latitude Return of warm surface waters to replace them
Slide 8
Energy from the Sun!
http://earthguide.ucsd.edu/earthguide/diagrams/greenhouse/
Slide 9
Energy Transfer to and from the Oceans Radiation Direct
transmission from source with or without a medium Three types of
heat transfer:
Slide 10
Energy Transfer to and from the Oceans Three types of heat
transfer: Radiation Direct transmission from source with or without
a medium Advection or Convection Transport of material and its
heat. Density-bouyancy driven movement of fluid
Slide 11
Energy Transfer to and from the Oceans Radiation Direct
transmission from source with or without a medium Advection or
Convection Transport of material and its heat. Density-bouyancy
driven movement of fluid Conduction Heat transfer by molecular
motion. Only works for bodies in direct contact. Three types of
heat transfer:
Slide 12
Radiation Balance for the Earth Fig. 6.12 The Sun heats Earth
more at the equator than at the poles! Did you see this link on the
course web site? N. Pole S. Pole equator
Slide 13
Radiation Balance for the Earth Earth's radiation balance is
approximately at "steady state (comparing one year to the next)
That is: outgoing rad= incoming rad (units are in percent of total
radiation either incoming (solar) or outgoing (long-wave) Note role
for latent heat transfer Dont worry about numbers, but note
complexity Albedo=30%
Slide 14
A temperature gradient is created from low (warmer) to high
(colder) latitude This drives heat transfer But how is this heat
transferred?
Slide 15
The Ocean-Atmosphere Connection, Winds & Surface
Currents
Slide 16
What drives atmospheric and ocean Circulation?
Slide 17
Radiation Balance for the Earth Albedo=30% Think about Solar
Radiation Reaching the Sea Surface
Slide 18
Solar Radiation Reaching Sea Surface (considers loss of
reflected energy by clouds, etc.) Units are Watts/meter 2 --compare
incoming patterns to outgoing in next slide
Slide 19
Long-wave (infrared) radiation out Notice that higher energy
loss values are association with tropics (warm), and values near
the pole exceed incoming solar (previous slide).
Slide 20
Average Sea Surface Temperatures So, the Temperature Pattern is
Determined by Solar Energy Receipt but Must be Modified by Heat
Transport \ Hot tropics Cold poles Strong Temperature gradient
Slide 21
Slide 22
The Pattern of Surface Water Ocean Circulation Ocean Currents
Transfer Heat
Slide 23
GLOBAL ATMOSPHERIC CIRCULATION (WINDS) Large Scale Winds
Transfer Heat, Note Air Pressure Zones
Slide 24
Wind and Ocean Currents are driven by heat imbalance
Slide 25
Slide 26
Which of the following are correct associations A) salinity and
thermocline, density and pycnocline, and temperature and halocline
B) salinity and halocline, density and thermocline, and temperature
and pycnocline C) salinity and pycnocline, density and thermocline,
and temperature and halocline D) salinity and halocline, density
and pycnocline, and temperature and thermocline E) none of the
above
Slide 27
Which of the following is (are) correct? C. The sun radiates
mostly short-wave energy (visible light), whereas the Earth
radiates long- wave energy (infrared). D. So-called greenhouse
gases absorb long-wave energy in the atmosphere and cause
temperature to increase. E. All of the above. C. The sun radiates
mostly short-wave energy (visible light), whereas the Earth
radiates long- wave energy (infrared). D. So-called greenhouse
gases absorb long-wave energy in the atmosphere and cause
temperature to increase. E. All of the above. A.If more solar
energy is retained by Earth than reflected or reradiated, Earths
atmosphere will warm. B.On average, about 30% of incoming solar
radiation is reflected back to space without an impact on Earth
surface temperature.
Slide 28
Which of the following statements is correct about the Earth?
A. Incoming energy from the sun is the primary means of heating the
tropics. B. Heat transfer from low to high latitudes plays an
important role in the pattern of ocean currents and large scale
winds C. Ocean currents and winds transfer heat from low to high
latitudes D. all of the above E. none of the above.
Slide 29
GLOBAL ATMOSPHERIC CIRCULATION (WINDS) Large Scale Winds
Transfer Heat, Note Air Pressure Zones
Slide 30
Warm air rises Air cools, sinks Rising air is replaced LOW
Pressure 030 S 30 N
Slide 31
Lets Consider Pressure Variations as a Cause for Winds Well
draw the windfields around these low and high pressure cells. Whoa?
Why do they look like that? Shouldnt winds blow directly from high
to low pressure centers? (well talk about the Coriolis effect as a
cause a bit later) Air should flow perpendicular to a pressure
gradient, from high (H) to low (L) pressure.
Slide 32
Winds around high pressure: clockwise in N. hemisphere and
Counterclockwise in S. hemisphere Global Pattern of Winds on Earth!
Low Pressure High Pressure Low Pressure
Slide 33
Credit: NASA Recall the uneven heating of the Earths surface
Lets examine how the Hadley Cell arises Heres the picture: why do
winds blow this way? Required viewing: A year of Weather. Note
large scale wind directions and storm circulation patterns from N.
to S. Hemisphere. (animation) Thanks to Justin D.
Slide 34
Warm air rises Air cools, sinks Rising air is replaced LOW
Pressure 030 S 30 N
Slide 35
Warm air rises Air cools, sinks Rising air is replaced LOW
Pressure HIGH Rising air cools, which causes Rain drops to form!
030 S 30 N
Slide 36
Air cools, sinks Divergent Wind Convergent Wind At Earths
surface, wind moves away from Highs Pressure and toward Lows LOW
Pressure HIGH 030 S 30 N Divergent Wind
Slide 37
Air cools, sinks Divergent Wind Convergent Wind LOW Pressure
HIGH 030 S 30 N Divergent Wind At Earths surface, wind moves away
from Highs Pressure and toward Lows
Slide 38
GLOBAL ATMOSPHERIC CIRCULATION (WINDS) Temperature gradients
create pressure differences which drive winds
Slide 39
Why is there generally low pressure over the equator and high
pressure at 30 N and 30 S? A. Lots of solar energy reaches the
equator and warms up the air, causing it to rise. B. The equator
receives a surplus of energy relative to polar regions, and this
causes winds, in the upper atmosphere, that blow North and South
away from the equator C. Downward winds at 30 N and 30 S cause high
pressure below them D. All of the above E. A and C
Slide 40
Question: Why dont the tropics boil and the poles freeze over?
A.Heat is Transferred from the tropics to the poles! B.Heat is
received only in the tropics and not at the poles! C.Polar regions
do not radiate heat. D.All of the above E.None of the above
Slide 41
Solar energy received at Earths surface is high in the zones
centered around about 20 N and S because: A.It is always summer
there B.These areas are generally clear and not covered by clouds
C.High pressure forms at the equator D.All of the above E.A and
C
Slide 42
Low Pressure High Pressure Low Pressure Global Pattern of
Pressure Cells and Winds on Earth!
Slide 43
Western Boundary Currents Gulf Stream, Kuroshio, Labrador,
Kamchatka (Oyashio) Eastern Boundary Currents Canary, California
Ocean Surface Currents Ocean's Role in Energy Transfer and Climate
Regulation
Slide 44
Western Boundary Currents Gulf Stream, Kuroshio, Labrador,
Kamchatka (Oyashio) Eastern Boundary Currents Canary, California
Ocean Surface Currents: Some Interesting Differences Between
Eastern & Western Boundary Currents
Slide 45
Gulf Stream as an example of a Western Boundary Current
Slide 46
East Australian Current & Gulf Stream are examples of
Western Boundary Currents
Slide 47
Western boundary currents are intensified --transport warm
water to higher latitudes
Slide 48
Surface currents transport heat toward poles
Slide 49
Example: The Gulf Stream Note these features: Sharp boundaries
of currents (1 & 2) Eddies Warm-core rings (3) Cold-core rings
(4) Labrador Current Gulf Stream This is a map of surface water
temperature Surface currents transport heat toward poles
Slide 50
Gulf Stream Heat Transfer: Is that all there is to it? OK, warm
water flows toward the poles, but How does heat actually get
transferred?? Two mechanisms: 1) Sensible heat transfer to
atmosphere 2) Latent heat transfer (remember: evaporation-
precipitation?)
Slide 51
1) Pattern of solar energy absorption leads to temperature
gradient 2) Heat transfer drives winds and ocean circulation. 3)
Sensible heat transfer (wind, currents) and latent heat transfer to
the atmosphere 4) Eastern and Western boundary currents Ocean's
Role in Energy Transfer and Climate Regulation Key factors &
processes
Slide 52
Gustav Why do winds circulate around High and Low pressure
systems?