Oceans and the Global Environment: Summary

1. Oceans and the Global Environment: Summary

2. Oceans and the Global Environment: Lecture 1 taking physics and chemistry outdoors Peter Rhines1Eric Lindahl2 Bob Koon2,Julie Wright3 Discovery Seminar 25 Aug-18 Sept 2008 University of Washington www.ocean.washington.edu/courses/has221a-08 1Prof. of Oceanography and Atmospheric Sciences; UW Honors Program 2GFD Lab, School of Oceanography 3M.S. in Biological Oceanography, UW

3. course goals learn about the oceans of Earth, and their importance to plants, animals including humans improve our relationship with the natural world…’Nature’ experiment calculate build ‘tools’ for your future (whether as a scientist or just a person) consider ‘deep’ environmentalism…the growing understanding of interdependence within Nature, which has roots in philosphy and art as well as science, and implications to medicine, business, law, international relations, global povery as well as to human-centered technologies.

4. keep a journal daily (In two forms: in a roughly 8 ½ x 11” bound notebook…UW Bookstore and as a Googe Document shared with the instructors online) • class lecture notes • lab experiment notes and results; sketches (diagrams), graphs, explanations • problem solving notes and results • reading: most interesting ideas; least interesting content • short essays which will be assigned; start your essay the day it is assigned and let it ‘grow’ in your notebook. When it begins to look complete put it into your Google document; label it as a draft until you are happy with it (some of these will be quick-turnaround, due the next day). (~typically 2 to 3 page essays) • As an aid to journal-keeping we will suggest some questions about the reading, lectures and in-class science problems which you can discuss in your journal.

5. Lec 1 the layered world

6. the Gulf Stream this morning…seen by NOAA infrared satellite sensors. We average for a week to get rid of clouds http://fermi.jhuapl.edu/avhrr/gs/

7. 104.50 angle formed by hydrogen- oxygen-hydrogen tetrahedon; covalent bond within the water molecule yet ‘hydrogen bond’ between molecules

8. Let’s remove Greenland’s ice (only temporarily)

9. Topography of the sea floor, constructed from satellite radar altimetry and direct acoustic ‘soundings’ from ships (Smith & Sandwell)

10. from Seagar, Introduction to Ocean Science, 2007

11. dissolved oxygen (in micro mols per kg of seawater), 1500W (purple = large, yellow=small)

12. the northern Atlantic Ocean…with its seafloor topography and the ice-mountain of Greenland (note vertical exaggeration of the picture! Greenland is about 3 km tall and 2000 km long…it lies between 600 N and 830 N, which is ¼ of the way from North Pole to Equator image:AGU 2003

13. Erika Dan temperature section from Labrador to Greenland to Ireland, 60N(red= warm, blue = cold)Worthington and Wright, 1962 surface 4 km deep

14. buoyant continents float like icebergs on top of denser mantle

15. question 1.1: how different is it to swim in Hawaii and to swim in Kansas? • question 1.2: Archimedes, according to legend, determined the king’s crown was gold, by knowing the density of gold. However the crown had a very elaborate shape, so he did not know its volume. “Aha” he said and fetched a basin of water. How did he use the water to learn the density of the metal in the crown? • question 1.3: how many barbers are there in New York city

16. Lec 2 the gyre circulations (greatand small)

17. And.. the result is this circulation of the upper few hundred meters of the oceans, more or less in the direction of the winds: ‘gyres’ that look like the wind yet are concentrated on the western sides of the oceans in currents like the Gulf Stream and Kuroshio (‘Black Current’) off Japan. This is the pressure field (simply related to the average height of the sea surface, by the hydrostatic pressure rule). Think of these as flow lines, with the currents forming clockwisegyres in the northern subtropics, and anti-clockwise gyres at high northern latitude. The sense reversesin the southern hemisphere, since the Earth’s rotation takes the opposite sense ‘down-under’. Because the flow between to adjacent flow lines involves the same volume of fluid flow, the speed of the currents is greater where the lines bunch together. The Gulf Stream and Kuroshio are ‘boundary currents’, very rapid (~ 2 to 4 knots…nautical miles per hour) as a result

18. the Southern Ocean connects the Atlantic, Pacific and Indian oceans, and the Antarctic Circumpolar Current circles round Antarctica in response to the very strong westerly (‘eastward’) winds

19. Since 1992 it has been possible to see this circulation from space, using radar altimeters on the Topex/Poseidon and JASON satellites of NASA and the European Space Agency. This a view of the global distribution of sea surface height. The gyres of circulation are not so clear because this instrument shows only the time-varying part of the pressure field. NASA is working to determine the background ‘mean circulation’ missing here, using a remarkable technology of the GRACE satellite mission. What you do see are thousands of swirling eddies which propagate slowly westward and sometimes originate inthe intensest currents…the Gulf Stream, Kuroshio, and Antarctic Circumpolar Current figure from Dudley Chelton, Oregon State Univ.

20. ? two dynamical ideas: pressure (weight of fluid overhead, per square meter) and angular momentum…figure skaters • The layers of ocean are not horizontal: so they must be moving. The forces acting on them are few: gravity and the stress of the wind overhead. Pressure variations within the ocean act to redistribute these external forces (like people elbowing one another in a crowd). So, how would you expect the pressure and velocity of the ocean to be related? atmosphere ocean higher pressure lower pressure

21. The peculiar laws of Newtonian physics, when applied to a rotating planet, say that a body tends to move perpendicular to the force exerted on it….not exactly but largely so. Here we have a ring of air (or water) centered on the North Pole. A northward force moves it toward the Pole. The angular momentum, H, of the ring is conserved: the product of distance from the rotation axis, and total east-west velocity. ‘Total velocity’ means the sum of the wind speed relative to the Earth, call it u, plus the Earth’s eastward velocity, Ωr. So H = ru + Ωr2 does not change, as r changes: as r decreases,u increases, corresponding to an acceleration of the eastward winds. This can be calledthe ‘figure-skater effect.’ The Earth spins at a rate Ω meaning that the length of the day is 2π/Ω. So Ω = 2 π/24 hours or 7.27 x 10-5 sec-1 Ω is called the angular velocity

22. The Greenland waters reaching out over the Labrador Sea also carry strong primary productivity with them…as seen in SeaWIFS ocean color (May 2004). We have been working in this region with robotic Seagliders, and have identified the physical circulation that enables the dominant plankton bloom of spring, seen here from the SeaWiFS satellite (again, yellow to red is high biological activity, blues are low activity).

23. 2005 days 91-120

24. Lec 3 the conveyor belt circulations

25. Benjamin Thompson (Count Rumford) 1753-1814:American colonist in Concord (Rumford) New Hampshire; allied himself with the British as the Revolutionary War approached, escaped to England and then Germany: yet he later endowed a professorship at Harvard. http://www.rumford.com/Rumford.html

26. P Convection in fluids: When we add Earth’s rotationto this heat convection, the ‘figure skater effect’ reorganizes the horizontal circulation. Basically, the ‘conveyor belt circulations’ now drive strong horizontal currents and lots of spinning, swirling eddies and strong, concentrated ‘jet streams’ This true both in the atmosphere and ocean which have remarkable similarities The ‘weather’ of the ocean (that is, the 100 km wide eddies) coexists with the global general circulation (the ‘conveyor’) just as the weather of the atmosphere coexists with its general circulation (the easterly and Westerly winds and the atmospheric conveyor belt circulation which tranports heat from warm latitudes toward the poles Convection without Earth’s rotation

27. When the Earth’s rotation comes into play, this pattern of convection currents is deflected at right angles into ‘east-west’ currents. The east-west flow breaks into complex, swirling eddies which we call ‘weather’.

28. Still images from the video of convection with Earth’s rotation…simulated in a bowl with an ice-filled cylinder in the middle. The ‘Arctic’ at the center cools the fluid, but rather than just flowing in a simple convection pattern as in the previous slides, Earth’s rotation and the figure-skater effect give the flow strong east-west acceleration. We see round eddies and jet streams snaking around them. These structures do the work of carrying heat from the warm latitudes to the cold latitudes. There are actually 2 jet streams: fluid sinks at the cold ‘northern’ wall and moves south. The angular momentum principle says that this fluid will develop a westward flow (turning to its right). Conversely, the fluid rising in the warm latitudes flows north to complete the circuit, but is deflected into an eastward jet stream, very intense. These complex ‘weather’ patterns do the necessary work of the atmospheric ‘heat engine’, moving heat poleward and converting thermal energy into kinetic energy of motion. The ocean has similar instabilities and eddies and jet streams, only they are 10 times smaller in width.

29. Southern hemisphere and northern hemisphere circulations: weather introduces new time-scales into high latitude life. Left is south polar view, right is north polar view. There are natural cycles over 10 years and longer, as well as global warming related change in weather patterns, temperature and rainfall. The jet streams are seen at the 300 HPa level (where just a few contours are selected to highlight the jets). There is a strong symbiosis between the synoptic highs and lows at the surface, the jet, and the smoother, faster stratospheric polar vortex above. Note the much more zonal nature of the SH flow. One glitch: colors in the NH are SLP while colors in SH are 850 HPa temperature….sorry for this confusion!(dynamic height at 1000 Hpa (colors: blue = low pressure cyclones, red=high pressure anticyclones), 300 Hpa, 30 Hpa 1993 (NH), 1996 (SH) winters, 100 days each northern hemisphere southern hemisphere UW-GFD lab hemisphere

31. Model of the oceanic conveyor belt circulation, driven by sources of deep water entering in the far north: Caitlin Whelan, summer undergraduate fellow, GFD lab UW 2007 fluid is pumped into the model ocean in the far north, and flows south along the western boundaries of each ocean basin, then recirculates in big gyres near the sea floor. This peculiar circulation occurs because of the ‘stiffening’ of the fluid by its planetary angular momentum vertical walls (simulating continents)

32. mid-depth deeper • smethie CFCs deepest ~ 3800m

33. Lec 4 • Flux or ‘transport’ defined for a flowing system with a reservoir: = concentration C x velocity U x area A F = C A U e.g. kg phosphate/m3 x m2 x m/sec = kg phosphate per second • Residence time (for a steadily flowing system) = mass of system/flux: Tresidence = mass/F (can be expressed as reservoir volume/Flux of volume)

34. Lec 5 Water

35. Lec 5-08 water, ice, snow and their future under global warming Peter Rhines Oceanography and Atmospheric Sciences, UW Honors Program University of Washington image: Petermann Glacier, NW Greenland Konrad Steffen Univ of Western Australia, 2x05

36. liquid water is a sort of ‘super molecule’ in which hydrogen bonds between molecules are fully 1/3 as strong as the interior bonds of each molecule….and hence we have life

38. water evaporates from the Great Lakes when cold north winds blow over them. It soon condenses back into water, as cloud droplets which then rain or snow out…The lake water has become cloud, and then the cloud piles up as deep snow, downwind of the lakes. This is called ‘lake-effect snow’.

39. change in rainfall predicted for last 20 yrs of this century…stripes of dry and wet which are similar to the present dry and wet regions…everything gets more extreme! Meehl et al. Geophysical Research Letters 2005

40. the legendary Ogallala aquifer supports much of the agriculture in dry central US regions..yet is depleting rapidly (1/5 the irrigated land in US, 40% of our cattle drank its water in 1970s) 40 to 100m below surface; water dates from last ice agethickness 0 – 300m. Decline of 9% between 1950 and 2005 (Wikipedia)

41. As China moves toward industrialization and a diet with more meat, it begins to use much more water, grain and other resources. The world grain harvest, once with a big surplus, seems to be turning into a deficit state. xxx gallons of water to raise 1 lb of beef: xxx = 5000 (environmentalist), or 435 (National Cattlemens Assoc.) www.beef.org

42. Lec 6 estuaries

43. http://green.kingcounty.gov/WLR/Waterres/hydrology/GaugeMap.aspxhttp://green.kingcounty.gov/WLR/Waterres/hydrology/GaugeMap.aspx

44. Segar, 2007 text

46. lab model of the conveyor belt circulation in an estuary open ocean river input Parker MacCready, UW Oceanography

47. Deep time showing the cooling of the Earth since the end of the Creaceous period (the dinosaur era). There was little or no snow or ice on Earth then. Abruptly, about 2.5 million years ago, the curve starts oscillating wildly: the beginning of the ice ages time Haug et al Nature 2006

48. Vogelherd horse carved 32,000 years ago from mammoth tusk. This, along with the cave paintings in France and Spain, represent the earliest discovered art works of humans. This was the peak of the last ice age, when glacial ice must have been just north of the site of this art. Development of human intelligence may have occurredat times of extreme climate and climate change.

49. What is our place among the millions of species on Earth…the only known life of the Universe?Top predator? Sentinal species? Fellow traveler on Spaceship Earth?Whaling by the Inupiat natives of Alaska’s north slope (image by Charles Wohlforth, author of The Whale and the Supercomputer. These bowhead whales weight about 100,000 lbs and may live in excess of 200 years. This says something about the stability of their environment.

50. how was the world before we arrived? How quickly will it repair if we are gone? an historian’s view: evolutionary strategies of rats and sharks: do we adapt or remain intoxicated by cheap energy? of the 5 major reasons civilizations succeed or fail, the environment is central to 3 and involved in all 5 destruction of forest catchments, aquifers and natural rivers, with their regional economies, commodification of water are acts of terrorism