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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.

  1. 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.
    1. What is Earth's equatorial radius? Give the answer in kilometers, nautical miles, and statute miles.
    2. What is Earth's equatorial circumference? Give the answer in kilometers, nautical miles, and statute miles.
    3. Assume Earth is a sphere with a radius equal to the equatorial radius.
      1. How many kilometers per degree of latitude? How many nautical miles?
      2. How many kilometers per degree of longitude at 60° N? How many nautical miles?

  2. 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 on.
    1. 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.

  3. Using an atlas (if you don't have a good atlas, use one in the library, or find a good online map):
    1. 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 figures.
    2. What is the distance from Los Angeles to Tokyo along 35° N? Give the distance in degrees and kilometers.

  4. 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.
    1. Are data from the world-wide ship data base sufficient to map all important sea-floor features? Please provide evidence that supports your answer.
    2. 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.
    3. Where are the missing features located? Give latitude and longitude and name of the oceanic area.
    4. Who distributes global bathymetric data sets based on altimetric and ship data? In what form are they distributed?
    5. 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.

  5. 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 reduced.

Revised on: 27 August, 2008

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