GEO/OC 103
MIDTERM 2 Study Guide
To study for the test, please consider the following material, listed
from highest to lowest priority:
- PRIORITY ONE (HIGHEST) The concepts and specific examples presented during the lectures, which you can review by downloading and looking at the PowerPoint (PPT) files. Remember, you MUST have a copy of Microsoft PowerPoint installed onyour computer in order to look at these files! And a word of warning about
the PPT files: it's NOT a good idea to print them in slide mode because of
the numerous graphics - just look at the slides on the computer and take
notes from them, or select only a few slides to print (or change the background
color to white and the text to black before printing).
The test will only cover the lectures on chemical
and physical oceanography and closely-related subjects, hence Lectures 10-20.
- PRIORITY TWO (NEXT HIGHEST)
The website notes in text format (but please keep in mind that the material emphasized
in lectures might be somewhat different than the website notes. You are
first and foremost responsible for taking your own notes on the concepts
presented in lecture).
- It doesn't hurt to look at the "Additional Resources" web links on the course lectures page as well.
- LOWEST PRIORITY (OPTIONAL) Background material in the optional Invitation to Oceanography textbook by Pinet (Chapters 5-8, 11).
It may also help to:
-
prepare for the exam by studying in a group with some of your classmates
- Study Tip: When studying, "close the book, recall, then write it down." Put the PowerPoints and notes aside. Then use the practice questions below as a guide and recall everything you can in order to answer the questions without the aid of your notes. Write your answers down, or say them out loud.
The following key topics should help guide your preparation
for the exam, 70% of which will consist of multiple choice and true false
questions worth 2 points each and 30% of written extended answer questions, worth 15 points each.
Properties of Sea Water
The most important things to know about this topic are the unsual properties
of water and their causes. These result from the dipolar structure of the
water molecule (e.g., Lecture 10), and the unsual properties include: (1) water
exists in three states; (2) it has a very high heat capacity;
(3) water is an extremely strong solvent; (4) it undergoes
unusual variations in density as the temperature changes, and ice (solid
water) has a lower density than liquid water. You should know
why water has these unusual properties.
Know the major constituents in sea water (e.g., know the top 6 salt ions). Understand what nutrients are, and why they
are important in the sea.
It is important to know the mean meaning of "salinity" and its effects
on the properties of sea water.
An extremely important topic is "Chemical and Physical
Structure of the Oceans." Be sure you know the difference
between the thermocline, halocline and pycnocline, and how (and why) they
change with the season and across the expanse of the ocean.
Review the concepts of the transmission of light and sound in the ocean
Ocean Acidification and Global Carbon
Study the PPT and notes provided from Dr. Jack Barth's guest lecture on that topic. You should know that
carbon dioxide (CO2) is going up exponentially and why. Is it rising at a rate that
we can to project from our scientific data and models?
Remember that the oceans help by absorbing literally tons of CO2.
You should know that we (humans) have changed the pH of the oceans by 0.1 (perhaps
by as much as 0.3 in the future), and what the implications are for life in the oceans,
especiallys corals and bivalves.
Remember that our emissions on land WILL change the ocean
Ocean Circulation and El Nino
It is important to understand the patterns of winds in the
atmosphere and what causes them, and how the winds in turn control the
patterns of surface water currents in the oceans. Both are "deflected"
by the Coriolis "force" due to the rotation of the Earth. The large scale
currents form gyres, with the western portions like the Gulf Stream being
the strongest. Each gyre is a geostrophic current where there
is a mound of water (an elevated sea surface) at the center which balances
the Coriolis force.
Deep-ocean circulation is determined by water densities, which in turn
are controlled by water temperatures and salinities (and hence is termed
thermohaline circulation).
Make sure to review the lecture notes on gas hydrates. Know what
they are and why we should be concerned about them.
Review the PowerPoint and lecture notes on El Nino
and La Nina and make sure that you understand the differences between
them.
Waves in the Ocean
Be sure to study the PowerPoint files and lecture notes on this topic closely
and to key in on the figures that were discussed in
lecture. You should know what the main parts of a wave are (crest, trough,
wave height, wave length, period). Wind-generated waves
are an important form of energy in the ocean, especially when they reach
the coast where they are fun to watch and play in but can also cause
a signifcant amount of coastal damage (especially erosion).
Tides
Again, be sure to study the PowerPoint file and lecture notes on this topic
and to key in on the figures that were discussed in lecture.
Satellite Oceanography
Be sure to study the PowerPoint file of the guest lecture by Dr. Ted Strub on this
topic closely. There WILL be material from this and the other guest lectures on the test!
PRACTICE Extended Answer (Essay) Questions
Discuss the oceanographic and coastal processes that are important in causing hurricanes to be so destructive to coastal communities.
The principal properties of hurricanes that cause the destruction of coastal communities are the enormous waves generated and the occurrence of a storm surge that raises water levels along the coast. In the Northern Hemisphere, due to the counter-clockwise rotation of the wind around the eye of the storm, both the waves and surge are greatest to the right of the eye.
Describe three types of breaking waves observed on beaches.
In spilling breakers, the crest becomes unstable and flows down the front part of the wave, resulting in frothy water remeniscient of a bore. In the surf zone, spilling occurs when steep waves advance up a gentle beach and continues over a number of wavelengths.
Plunging is the most dramatic form of breaking, with the crest curling over and crashing into the water below, creating a large splash which advances like a bore. Plunging occurs on slightly steeper beaches and often within a single wavelength.
Surging occurs on the steepest beaches: the crest does not break, but the base of the wave's front face advances rapidly up the beach with mild breaking and significant reflection.
Why is the water along Oregon’s beaches usually warmer in the winter than in the
summer?
It all starts with the wind!!! Summer winds along the coast blow from North to South, causing Ekman transport to carry inshore waters out to sea, which are replaced by cold, nutrient-rich bottom waters (upwelling). So water along beaches is normally very cold. In winter, primary wind direction is from south to north so opposite effect occurs and warmer surface waters are brought inshore by Ekman transport.
A couple more practice questions:
How is a La Nina different from an El Nino?
Describe the sequence of events that characterize El Nino conditions in the equatorial Pacific Ocean.
What are gas hydrates and why should we be concerned about them?
Last updated May 6, 2011
http://dusk.geo.orst.edu/oceans/guide2.html
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