1 Lecture 10: Wind Introduction to Oceanography Chris Henze, NASA Ames, Public Domain, http://people.nas.nasa.gov/ ~chenze/fvGCM/frances_02.mpg Winds at ~jet plane altitude Introduction to Oceanography Pacific surface wind forecast-hindcast, National Weather Service Environmental Modeling Center/NOAA, Public Domain, GIF by E. Schauble using EZGif
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Introduction to Oceanography Chris Henze, NASA Ames, Publicschauble/EPSS15_Oceanography/LEC10S17_… · 2 pH Scale • pH scale = Logarithmic scale • Neutral (pure) water: – 1/(5.5x108)
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Transcript
1
Lect
ure
10: W
ind
Introduction to Oceanography Chris Henze, NASA Ames, Public Domain, http://people.nas.nasa.gov/
~chenze/fvGCM/frances_02.mpg
Winds at ~jet plane
altitude
Introduction to Oceanography
Pacific surface wind forecast-hindcast, National
Weather Service Environmental Modeling
Center/NOAA, Public Domain, GIF by E. Schauble
using EZGif
2
pH Scale • pH scale = Logarithmic scale
• Neutral (pure) water:
– 1/(5.5x108) water molecules is disassociated – there are about 55 moles of water per liter Concentration of H+= 55/(5.5x108) = 10–7 moles/liter
– Neutral water pH = 7 • lower pH = acid, higher pH = base
€
pH = − log10(H +)
pH Scale
Stephen Lower, Wikimedia Commons,
CC A S-A 3.0, http://en.wikipedia.org/wiki/
File:PH_scale.png
3
The Carbonate Buffer System • Seawater pH = ~8.0 (slightly basic) • Maintained by carbonate buffer system:
• Increase CO2 in water, acidity increases What happens to pH?
• Add acid and CO2 is produced
€
CO2 + H2O ⇔ H2CO3 ⇔ H+ + HCO3− ⇔ 2H+ + CO3
2–
Carbonic Acid Bicarbonateion
Carbonateion
The CO2 system and carbonate
• Deep waters form at the poles: High CO2 and therefore acidic
• Acidity interacts to dissolve calcium carbonate (CaCO3) deposits on the deep sea floor – Acidity and temperature control carbonate
compensation depth (CCD)
4
Questions
Image from UNESCO, Presumed Public Domain, http://ioc3.unesco.org/oanet/FAQacidity.html
Wind
• Lecture 8: Atmospheric Circulation
Wind sea, N. Pacific, Winter 1989, M/V NOBLE STAR/NOAA, Public Domain, http://commons.wikimedia.org/ wiki/File:Wea00816.jpg
5
Atmosphere-Ocean Coupling
• Why study atmospheric circulation? – Atmosphere & ocean processes are
• Equator absorbs more heat from the sun than it radiates away (net > 0). • Polar regions radiate much more heat than they absorb from the sun(!) • E.g., Equator isn’t that Hot; Poles aren’t that Cold • Evidence that the atmosphere (~2/3) & oceans (~1/3) redistribute heat • Result: convective heat transfer moderates climate
CERES/NASA animation, Public Domain, http://earthobservatory.nasa.gov/GlobalMaps/view.php?d1=CERES_NETFLUX_M
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Redistribution of Solar Heat Energy
• Convective heat transfer moderates Earth climate • Heated air expands & rises, then cools & sinks
EQU
ATOR
POLE
S
Adapted from image at http://www.yourhome.gov.au/technical/images/62a.jpg, Public Domain?
Atmospheric Circulation Without Rotation
Warm, less dense air rises
near the Equator
Cold, more dense air sinks near the Poles
Cold, more dense air sinks near the Poles
Background image from Smári P.
McCarthy, Creative Commons A S-A 3.0,
http://commons.wikimedia.or
g/ wiki/File:Earth_equator
_northern _hemisphere.png
12
Questions
Not quite right!
ACTUAL Atmospheric Circulation
Figure from NASA, Public Domain, http://sealevel.jpl.nasa.gov/overview/climate-climatic.html
13
Lab Coriolis Movies
• Movies made by Rob Hyde, UCLA
Lab Coriolis Movies
Stat
iona
ry O
bser
ver
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Lab Coriolis Movies C
CW
Rot
atio
n, 2
5 rp
m
Lab Coriolis Movies
CW
Rot
atio
n, 4
1 rp
m
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Coriolis Effect Movies
Movie: University of Illinois (not sure if that’s the original source) http://ww2010.atmos.uiuc.edu/%28Gh%29/guides/mtr/fw/crls.rxml
The Coriolis Effect on Earth
National Snow and Ice Data Center, free for educational use, http://nsidc.org/arcticmet/factors/winds.html
• Surface velocity increases from pole to
equator • Points on the equator
must move faster than points near the poles to go around once a day • Latitude velocity
differences lead to curving paths
– Example: Merry-go round
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The Coriolis Effect • To an Earthbound observer (i.e., us): • Northern Hemisphere: Earth’s
rotation causes moving things to curve to their right
Moving things: Air masses, oceanic flows, missiles, anything with mass
• Southern Hemisphere: Earth’s rotation causes moving things to curve to their left
National Snow and Ice Data Center, free for educational use, http://nsidc.org/arcticmet/factors/winds.html
The Coriolis Effect
• Strength of Deflection varies with latitude: – Maximum at the poles – Zero(!) at equator
– Faster a planet rotates, the stronger the Coriolis effects
– The larger the planet, the stronger the Coriolis effects
Northern Hemisphere: Hurricane Isabel (2003) NASA, Public Domain, http://visibleearth.nasa.gov/view_rec.php?id=5862
But wait – why do storms (including hurricanes and cyclones) go
backwards?
Atmospheric Circulation including Coriolis
Figure from NASA, Public Domain, http://sealevel.jpl.nasa.gov/overview/climate-climatic.html
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Actual forecast of
surface winds
Pacific surface wind forecast-hindcast, National
Weather Service Environmental Modeling
Center/NOAA, Public Domain, GIF by E. Schauble
using EZGif
Atmospheric Circulation including Coriolis
• 3 convection cells in each hemisphere – Each cell: ~ 30o latitudinal width
• Vertical Motions – Rising Air: 0o and 60o Latitude – Sinking Air: 30o and 90o Latitude
• Horizontal Motions – Zonal winds flow nearly along latitude lines – Zonal winds within each cell band
• DUE TO DEFLECTIONS BY CORIOLIS!
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Atmospheric Circulation including Coriolis
3 Cells per hemisphere: Polar
Active (updraft on hot side, downdraft on cold side)
Ferrel Passive (downdraft on
hot side!) Hadley
Active H
AD
LEY
POLAR
FERREL
UCLA figure – background image unknown.
Atmospheric Circulation including Coriolis
• Latitudinal winds: – 0-30o: Trade
Winds – 30-60o:
Westerlies – 60-90o:
Polar Easterlies
Figure by Hastings, Wikimedia Commons, Creative Commons A S-A 1.0 Generic, http://en.wikipedia.org/wiki/File:AtmosphCirc2.png
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Atmospheric Circulation including Coriolis Cell Boundaries:
60o: Polar Front
30o: Horse Latitudes
0o: Doldrums
Vertical air movement (up at Polar Front and Doldrums, down at Horse Latitudes)
Doldrums
Horse Latitudes
Polar Front
Figure by Hastings, Wikimedia Commons, Creative Commons A S-A 1.0 Generic, http://en.wikipedia.org/wiki/File:AtmosphCirc2.png
Questions
Figure from NASA, Public Domain, http://sealevel.jpl.nasa.gov/overview/climate-climatic.html
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Local Meteorology of Southern California
Marine layer against the Southern California mountains Photo by Dr. Jonathan Alan Nourse, CalPoly Pomona, http://geology.csupomona.edu/janourse/Storms,%20Floods,%20Landslides.htm