Oceanography 2011 Final Third of Course
From my notes, these are the general topics that we actually covered since the second exam on March 23.
Refer to the review sheets that I already have posted on the website for an expanded list of information associated with each topic.
Marine sediments
terrigenous sediments
biogenic sediments
other types of sediments (volcanogenic, authigenic, cosmogenic)
In-class exercise to match sediment types with where in the ocean they probably came from
(exercise was handed back)
Core transect across the Pacific Ocean
included a handout with sediment types in the cores
and reconstruction of the conditions
Carbonate Compensation Depth – CCD
chemistry of CO2 dissolved in seawater, and effect on CaCO3 sediments
Photosynthesis and respiration as opposite directions of the same basic chemical equation
added later: how nutrients such as N (as NO3) and P (as PO4) are included in these processes
important to understand the difference between:
inorganic N and P dissolved in seawater
organic N and P removed from seawater to produce organic material (e.g., phytoplankton cells)
How science works, and the contribution of science to society, policy making, and citizenship in a democracy
observation, theory, verification
important: “theory” in science does not mean “conjecture” or “speculation”
Basic chemistry – each student is responsible for reviewing the basics
(summary and presentation available on our website)
Properties of seawater – important topics are incorporated into Exercise 5 (which was handed back)
Deep-ocean circulation
important: distinguish between the shallow ocean (above ~1000 m) and deep ocean (below 1000 m)
What processes or forces move water in the shallow ocean? In the deep ocean?
Density stratification and structure of the world ocean
remember the clines
Map showing deep-ocean circulation
know: NADW and AABW what are they, where do they form
Continuity – absolutely important for any of our discussion of atmospheric and oceanic circulation
can you give a clear, concise explanation of continuity?
Energy balance for the Earth surface
what happens to solar energy as it enters the Earth’s atmosphere?
fundamentals of the atmospheric greenhouse effect
Coriolis effect / Coriolis force
important: water or air moving in the Northern Hemisphere will bend to the RIGHT b/c of Coriolis
(bends to the LEFT in the Southern Hemisphere)
Atmospheric high and low pressure systems
cyclonic – think “cyclone,” as in “tornado”
RISING air, low pressure, spins counter-clockwise in the Northern Hemisphere
anti-cyclonic
SINKING air, high pressure, spins clockwise in the Northern Hemisphere
Orographic effect – air moving up and over a mountain range, then coming down the other side
important: drawn on the board, but the principles apply more broadly than just over mountains
what happens to warm, moist air flowing off the Pacific as it crosses the Sierra Nevada Mountains?
also important: relative humidity, absolute humidity, dewpoint, compression or expansion of air
Atmospheric circulation
most important point: atmos & ocean circulation are redistributing heat across the planet surface
be able to recreate the primary circulation structure of the atmosphere
that is, the Tropical Convergence, Hadley Cells, Ferrel Cells, Trade Winds, Westerlies, Polar Easterlies
Dynamic topography of the ocean surface
“sea level” is not flat
how measured? satellite altimetry (radar to measure the elevation of the water surface)
same dataset can be processed to show:
seafloor features (such as mid-ocean ridges, trenches, seamounts)
ocean currents
wave heights
Surface-ocean circulation
important: direct interaction between atmos circulation and major gyres in the ocean basins
use the North Atlantic Ocean as a model basin
what is the general pattern of circulation, what is driving the water, why an asymmetry
Ekman transport – fundamental process related to moving surface water in the oceans
geostrophic flow – from Exercise 6 (as shown on the board in class)
means “Earth turned”
create a mound of water with Ekman transport
water flows “downhill” but is turned by Coriolis
net result is water flowing “around the mound”
western boundary currents – Gulf Stream and Kuroshio Current are examples
be able to draw a west-east cross section of the water surface across the North Atlantic Ocean
steep slope on west side drives the Gulf Stream
how is the Gulf Stream different than the Canary Current on the east side of the basin?
Two types of upwelling
equatorial divergent upwelling
Trade Winds and Ekman transport move water away from the Equator
continuity replaces surface water by drawing water up from 200-400 m depths
coastal upwelling
two good examples: coast of Peru, coast of California
prevailing winds blow parallel to the coast
cause Ekman transport away from the coast (surface water moves offshore)
continuity replaces surface water by drawing water up from 200-400 m depths
in both cases of upwelling, the upwelling water is cold and rich in nutrients
this supports high productivity of phytoplankton, and lots of zooplankton and fish
Global Climate Change
presented observed, time-series evidence for global climate change over timescales
of decades to millennia (10’s to 1000’s of years)
a PDF of the presentation is available on our course website (Final Third of the Course)