lecture 6 geosc 040 chemistry of seawater –dissolved gas & density atmospheric circulation...
TRANSCRIPT
![Page 1: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/1.jpg)
Lecture 6 Geosc 040Chemistry of seaWater –Dissolved Gas & DensityAtmospheric Circulation & Ocean Circulation
Today’s music:
Behind the Sea- Panic! At the Disco
Thanks to Ashley K
Ocean Salinity Map
Home By the SeaGenesis
Bridgit Mendler – Hurricane
Thanks to Brenna M
![Page 2: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/2.jpg)
Thanks to Justin A.
Read Chapter 6 and course web siteNote required reading: Greenhouse gasses and global warming
Homework 1 Due TodayQuiz 1, Feb 7
PSU 71 !!!OSU 70
![Page 3: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/3.jpg)
Gases are dissolved in Seawater!
•Nitrogen (N2) 78.08•Oxygen (O2) 20.95•Carbon dioxide (CO2) 0.03 (365 ppm)•Argon, Helium, Neon (Ar, He, Ne) 0.95
% in atmosphere
![Page 4: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/4.jpg)
What controls variations in oxygen and carbon dioxide with depth in the ocean?
![Page 5: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/5.jpg)
Dissolved Gases in Seawater
Indicates:Oxygen production in
surface watersConsumption of
oxygen below surface waters
Indicates:CO2 consumption in
surface watersProduction of CO2 in
deep waters
Depth profiles of dissolved oxygen and dissolved carbon dioxide
Photosynthesis
Respiration
![Page 6: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/6.jpg)
Density of Seawater
Recall that Oceans have about 35 grams salt per kg water (salinity = 35 ppt or 35 PSU) (PSU= Practical Salinity Units)
• Density of seawater increases as• Temperature drops• Salinity increases
• Maximum density and freezing point coincide for 24.7 ppt• Note that ppt = %O
• At higher salinities seawater reaches maximum density at freezing point
![Page 7: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/7.jpg)
Seawater salinity:
Which is/are True?
A. The most abundant element dissolved in seawater is Cl
B. The element sodium is present in table salt and it is dissolved in seawater
C. We have a homework exercise due today and a quiz on Feb 7
D. All of the above
E. A and B
![Page 8: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/8.jpg)
![Page 9: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/9.jpg)
General Classification of Water Masses
• Why is ocean water stratified into these layers?• What are the characteristics of each of these regions?• Why do we care?
![Page 10: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/10.jpg)
Zone of Light Penetration(the Photic Zone)
![Page 11: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/11.jpg)
Shorter wavelengths of visible light (e.g. blue) penetrate deeper than longer wavelengths (e.g. red)
Zone of Light Penetration(the Photic Zone)
![Page 12: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/12.jpg)
The Energy Cycle
Note that photosynthesis (and formation of plant organic matter) requires sunlight and nutrients
Organic matter is consumed by animals and plants (respiration), supporting their growth
Nutrients must be “recycled” (excreted by animals, “regenerated” by bacteria) to be reused by plants
Photosynthesis
Consumers
Consumers
nutrients
Hey, did younotice that blue light penetrates
deeper?
duh… anybody
knows that
![Page 13: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/13.jpg)
Surface Zone (mixed layer)
Zone of rapid change with increasing depth
• Temperature and salinity vary considerably in the ocean• Because water has low viscosity and can flow, denser water
masses sinkwhile less dense water masses rise to the surface
• Deep water masses have a rather narrow range of T and S• Most T and S variability occurs in surface or near-surface waters• The ocean is density stratified (this is a stable configuration)
Density of Seawater & Stratification
Pycnocline is the zone of rapid density change with depth
![Page 14: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/14.jpg)
Density of
Seawater
![Page 15: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/15.jpg)
![Page 16: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/16.jpg)
500 to 2000 years!
t =
What is the residence time of deep water in
the large ocean basins?
![Page 17: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/17.jpg)
Ocean Surface Currents
![Page 18: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/18.jpg)
Ocean Currents Are Driven by Seawater Density
Salinity (S) - Temperature (T) - Density Diagram• note dual effects of S & T• typical range of seawater S & T
Define Sigma t :
t = (Density-1.0) x 1000
For example: seawater with a density of 1.026
would have t = 26
We'll use this diagram to differentiate water masses
Increasing
Density
![Page 19: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/19.jpg)
More complete Salinity- Temperature- Density Diagram for the normal range of salinity and temperature in the oceans. You should become familiar with this diagram.
t = 21
t = 24
t = 29
t = (Density-1.0) x 1000
![Page 20: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/20.jpg)
Let’s look at this in a bit more detail.
1
2
What is the density of 1 vs. 2?
Which is more dense?Water masses 1 & 2 have same S (35 o/oo) But 2 (at 4°C) is colder than 1 (20°C)Therefore: Water mass 2 (t = 27.7) is more dense than water mass 1 (t = 24.8)
![Page 21: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/21.jpg)
t: Salinity, temperature, density diagrams
A
C
D
B A. Which water mass is most like average deep water in the ocean?
B. Which water mass is most likely to be at the Ocean Surface?
C. Which water mass is most dense?
D. Which water mass has t of about 23?
Answer by entering the number (A, B, C or D) on your clicker
![Page 22: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/22.jpg)
t: Salinity, temperature, density diagrams
A
C
D
B A. Which water mass is most like average deep water in the ocean?
B. Which water mass is most likely to be at the Ocean Surface?
C. Which water mass is most dense?
D. Which water mass has t of about 23?
Deep Water is Cold and Salty
![Page 23: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/23.jpg)
A
C
D
B A. Which water mass is most like average deep water in the ocean?
B. Which water mass is most likely to be at the Ocean Surface?
C. Which water mass is most dense?
D. Which water mass has t of about 23?
t: Salinity, temperature, density diagrams
Answer by entering the number (A, B, C or D) on your clicker
![Page 24: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/24.jpg)
A
C
D
B A. Which water mass is most like average deep water in the ocean?
B. Which water mass is most likely to be at the Ocean Surface?
C. Which water mass is most dense?
D. Which water mass has t of about 23?
t: Salinity, temperature, density diagrams
Answer by entering the number (A, B, C or D) on your clicker
![Page 25: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/25.jpg)
t: Salinity, temperature, density diagrams (in class) 1
3
4
2 This plot shows four water masses.
Which of the following is/are true:
A) 2 has lower density than 1
B) 4 has the lowest densityC) 2 has t (sigma_t) of 28D) the ocean’s deepwater is
most like 1E) none of the above
![Page 26: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/26.jpg)
The concentration of dissolved oxygen in seawater is, in part, determined by:
A. The water temperature
B. The water salinity
C. The relative amount of respiration
D. The relative amount of photosynthesis
E. All of the above
![Page 27: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/27.jpg)
Energy from the Sun!
Is that the end of the story?
Did you know?
Earth’s average surface temperature is 15°C
The moon’s average surface temperature is more than 30°C colder than Earth’s.
Why?
http://earthguide.ucsd.edu/earthguide/diagrams/greenhouse/
It’s all about the Atmosphere
![Page 28: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/28.jpg)
The Role of the Atmosphere in Earth’s Temperature
The “greenhouse effect” is the higher temperature that the Earth experiences because certain gases in the atmosphere (water vapor, carbon dioxide, nitrous oxide, and methane, for example) trap and re-radiate energy. Without these gases, heat (long-wave radiation) would escape back into space and Earth’s average temperature would be about 33ºC colder. These gases are loosely referred to as “greenhouse” gases.
http://earthguide.ucsd.edu/earthguide/diagrams/greenhouse/
Go to this website to see an animation that illustrates the “greenhouse effect.” Ignore, for a moment the pronouncements at the end of the animation--we’ll get to that later.
![Page 29: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/29.jpg)
Average Sea Surface Temperatures
What Causes this Temperature Pattern?
Hot tropics
Cold near the poles
Strong Temperature gradient
-2° C 30° CSea Surface Temperature
![Page 30: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/30.jpg)
Wind and Ocean Currents are driven by heat imbalance
![Page 31: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/31.jpg)
Radiation Balance for the Earth
Fig. 6.12
The Sun heats Earth more at the equator than at the poles!
N. Pole
S. Pole
equator
![Page 32: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/32.jpg)
Sun’s energy (solar heat) is radiated to Earth and received unevenly
Solar energy received at any location on Earth varies with latitude, because the sun angle changes with latitude.
It’s easier to get a tan at the equator than at the north pole!
Sun angle varies with seasons because Earth’s axis of rotation is tilted relative to the plane of our orbit around Sun.
![Page 33: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/33.jpg)
Sun’s energy (solar heat) is radiated to Earth and received unevenly
![Page 34: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/34.jpg)
EARTH’s ORBIT (elliptical)
SEASONALITY
Effects of Earth’sAxial Tilt--A. Northern Hemisphere summer(solstice) occurs when tilt is towards the sun.
Systematic variation in solar energy receipt on a yearly basis is produced by Earth’s axial tilt and orbit around the sun.
Elliptical orbit causes about 3.5% variation too.
The Earth is actually closer to the sun in January
![Page 35: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/35.jpg)
Earth’s radiation balance is approximately at “Steady state,” which means that it doesn’t change much from one year to the next
A Balanced Budget means:Outgoing Radiation is approx. equal to Incoming Radiation
If the radiation budget were not balanced, Earth would either warm up or cool off over long periods of time!
This indicates that Earth must re-radiate energy equal to the amount that it receives from the sun.
Radiation balance for Earth
![Page 36: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/36.jpg)
The Earth radiates energy in the form of infrared (long-wave) radiation, which is emitted in proportion to the Earth’s surface temperature
The previous slides provided a global summary of Earth’s radiation budget.
But solar energy input is not evenly distributed across the Earth’s surface.
At high latitude outgoing longwave rad. exceeds incoming solar (see figure)
This creates zones of surplus and deficiency
![Page 37: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/37.jpg)
Question: Why don’t the tropics boil and the poles freeze over?
Answer:Heat Transfer -from the tropics to the poles!
Because a temperature gradient is created from low (warmer) to high (colder) latitude, heat must be transferred to compensate for the high-latitude thermal deficit.
But how is this heat transfer accomplished?
![Page 38: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/38.jpg)
The Ocean-Atmosphere Connection, Winds & Surface Currents
![Page 39: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/39.jpg)
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
![Page 40: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/40.jpg)
GLOBAL ATMOSPHERIC CIRCULATION (WINDS)Large Scale Winds Transfer Heat, Note Air Pressure Zones
![Page 41: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/41.jpg)
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
![Page 42: Lecture 6 Geosc 040 Chemistry of seaWater –Dissolved Gas & Density Atmospheric Circulation & Ocean Circulation Today’s music: Behind the Sea- Panic! At](https://reader035.vdocument.in/reader035/viewer/2022062516/56649d955503460f94a7d88b/html5/thumbnails/42.jpg)
The Pattern of Surface Water Ocean CirculationOcean Currents Transfer Heat