Introduction to Physical Oceanography
Homework Set 1
Due 3 September 2008
Late homework will cost 15 points per week or part of a week it is late.
The goal of this assignment is to give you practice in reading
maps, calculating distances from maps, and to help you understand how the
latest bathymetric maps of the ocean are made. In giving
your answers, please use the appropriate number of significant
figures. If you are not sure how to determine the number of significant
digits, consult the tutorial provided
by the physics department of the University of Guelph.
- Oceanography uses the International
System of units, commonly called the metric system, but English
maritime units, nautical miles, and nautical miles per hour
(knots), are commonly used, hence it is useful to at least
know about the units and how to convert among them.
Please use conversion rates based on international definition of units.
I expect accuracy of around four significant digits.
- What is Earth's equatorial radius? Give the answer in kilometers, nautical
miles, and statute miles.
- What is Earth's equatorial circumference? Give the answer in kilometers,
nautical miles, and statute miles.
- Assume Earth is a sphere with a radius equal to the equatorial radius.
- How many kilometers per degree of latitude? How many nautical
- How many kilometers per degree of longitude at 60° N?
How many nautical miles?
- Assume an oceanographic ship
moves at 12 knots and that it stops every degree of latitude and
makes hydrographic measurements for two hours before continuing
- How long does it take the ship to cross the Pacific
along the Equator going west from the coast of Ecuador in South
America to the east coast of Sumatra (ignoring
any deviations required to avoid islands)? Give your answer
in days plus hours. You will need an atlas to get the geographic
location of the coasts. I expect you can determine the location
of the coast within one degree, and it is not hard to get 0.1
degree accuracy. This question is a little tricky, the obvious
answer may not be correct.
- Using an atlas (if you don't have a
good atlas, use one in the library, or find a good online map):
- What is the distance from Honolulu to Rarotonga? Give the
values in degrees and in kilometers. (To simplify the calculation,
you may assume Honolulu is due North of Rarotonga.) In giving
the answer, please use the appropriate number of significant
- What is the distance from Los Angeles to Tokyo along 35° N?
Give the distance in degrees and kilometers.
- The latest bathymetric
maps of the ocean are made by combining altimeter and
ship data. To learn more
about the technique, read Sandwell and Smith's paper at
Global Bathymetric Prediction for Ocean Modelling and Marine
Geophysics and go to
NGDC/WDC A for MGG - Predicted Global Seafloor Topography
Information and read the paper on Exploring
the Ocean Basins with Satellite Altimeter Data by
Sandwell and Smith on how altimeters are able to observe
bathymetric features. You may also wish to read Section
3.4 of the Class Notes.
- Are data from the world-wide ship data base sufficient to map
all important sea-floor features? Please provide evidence that
supports your answer.
- What important subsea feature or features were missed in the
example cited in Sandwell and Smith's paper on "Global Bathymetric Prediction for Ocean
Modelling and Marine Geophysics"? Cite specific examples.
- Where are the missing features located? Give latitude and longitude
and name of the oceanic area.
- Who distributes global bathymetric data sets based on altimetric
and ship data? In what form are they distributed?
- While you are logged on,
look at the ETOPO-2 topographic
data and maps. Click on the area off north west Africa, and enlarge
the map by further clicking. Are there features in the map that
may be incorrect? Describe the feature and offer an explanation
of how how they might arise.
- Give an example of a sampling
problem appropriate to your work. Show how it meets the criteria
for a sampling problem. Show also how the sampling error might be
Revised on: 27 August, 2008