The following portion of the Investigation file is
provided to DataStreme Ocean course participants in the DataStreme Ocean
Investigations Manual. Investigations begin with a pre-printed portion in
the Investigations Manual and are completed with an online portion.
> For more information on the DataStreme Ocean course, click on the
ship cartoon "Welcome to DataStreme Ocean" to the right of the
heading on the DataStreme Ocean Homepage.
> For the location of the DataStreme Ocean Local Implementation Team (LIT) nearest you, click on "Locate DS-Ocean Team by State". You can also go to: DS Ocean LITs in the Extras section of the DataStreme Ocean website.
Educational Outcomes: There are many reasons for studying Earth's ocean. We have traversed the ocean for millennia, many have relied on it as a food source, and now its surface is plied for commerce and recreation. Ocean coasts increasingly attract human habitation. We maintain a few ocean outposts, such as oil platforms, for resource extraction and scientific investigations. As we learn more about the workings of the Earth system, we are becoming more aware of the significance of the ocean for our existence whether we live near or thousands of kilometers from its vast expanse.
DataStreme Ocean is an innovative study of the world ocean that promises to deliver new understandings and insights into the role of the ocean in the Earth system and to ways of incorporating ocean topics in K-12 classroom studies. The DataStreme Ocean paradigm presented in this Benchmark Investigation employs an Earth system science approach.
After completing this investigation, you should be able to:
Exploring the Earth system requires extensive use of various methods for displaying scientific information.
Map projections (two-dimensional representations) printed on flat sheets of paper or viewed on screens are common and convenient ways to portray Earth's surface. Road maps and weather maps are examples. But like all graphical models, maps have their limitations. Over great distances, such flat maps cannot faithfully represent the Earth's surface because of the simple fact that our planet is not flat! Depictions of a curved planetary surface on a flat map surface introduce distortions. The greater the curvature of the surface (e.g., more of the Earth's surface being depicted), the greater is the distortion.
Maps covering major portions of Earth's surface are typically constructed for conformality (whereby all small figures on the Earth's surface retain their original shapes on the map) or to preserve equal areas, that is, a constant ratio of areas. Maps cannot be both conformal and equal-area at the same time. For a detailed discussion of map projections, go to:
http://erg.usgs.gov/isb/pubs/MapProjections/projections.html
or
http://www.colorado.edu/geography/gcraft/notes/mapproj/mapproj.html
Figure 1: Sample Conformal Map
Maps are used extensively in oceanography and often depict huge areas of coverage. Global-scale projections undergo considerable distortion because the entire surface of a sphere is being projected onto a single flat surface. Even so, such depictions can be extremely useful although the user should be aware of their strengths and limitations. Maps can generally be classified as either conformal or equal area. Conformal maps are often adequate for depicting the configuration of some property. Figure 1 is a conformal map. It is a Mercator-type conformal projection that maintains the shapes of small regions and has lines of latitude and longitude forming a rectangular grid. Its major weakness is that surface area is greatly exaggerated at higher latitudes.
Equal-area maps can sufficiently portray the areal extent of properties as a constant scale of areas is maintained. Figure 2 is a world equal area-type display. Equal-area maps commonly suffer because the curving of longitude and latitude lines distorts shapes.
Figure 2: Sample Equal-Area Map
Think Globally: While flat maps are essential and useful tools in Earth system studies, the true relations of properties and Earth locations can only be displayed on a model that imitates the true shape of our spherical planet-a globe. A spherical globe is both conformal and equal area in its representation of the Earth's surface, thereby eliminating the distortions introduced by flat map projections. Globes are especially useful in the classroom because they can eliminate a potentially major obstacle (distortion) to learning. It is not easy for many learners to separate real patterns or relationships from those patterns or relationships that appear simply because of the way the information is presented. In other words, globes can be a great way to start the learning process. (Globes are not without their limitations, however. The biggest one is that they are not flat!)
DataStreme Ocean utilizes both flat-map and globe representations in its investigations of the Earth system. The DataStreme Ocean globe will be employed to introduce and/or reinforce Earth system fundamentals and to provide comparisons with the more common flat-map depictions of scientific information.
Figure 1 is a Mercator flat map. A major characteristic of such conformal maps is that lines of longitude and latitude are [(curved) (straight and perpendicular to each other)]. The map also shows that the distance between adjacent lines of latitude [(increases) (remains the same) (decreases)] as latitude increases toward the polar regions.
Figure 2 is an equal-area projection. Compare the apparent sizes of Greenland and Africa on each of the maps in the two figures. Their sizes on the Figure 1 Mercator map suggest they are about the same size whereas on the Figure 2 equal-area map it is apparent that Greenland is [(much smaller) (about the same size) (much larger)] than Africa.
A Global View: Hold your inflated DataStreme Ocean globe in front of you to examine the geographic grid of straight lines printed on it. These are the east-west parallels of latitude and north-south meridians of longitude. The equator, the 0 degree latitude line, is the largest circle on this spherical globe and lies in a plane that is perpendicular to Earth's rotational axis. The equator is called a great circle because it divides Earth into two equal hemispheres, in this case, the Northern and Southern Hemispheres. A series of other east-west lines are drawn at regular north-south intervals; these are the parallels of latitude. They are labeled along the north-south 180° longitude line. Generally, these latitudes in the Northern Hemisphere (equator to North Pole) are labeled positive (or North, N) whereas those from equator to South Pole are negative (or South, S).
A series of other great circles appear on the globe passing through the North and South Poles. These are longitude lines and represent angular measurements around Earth in east/west directions. They are measured from an arbitrarily chosen line termed the Prime Meridian, half of a great circle running between North and South Poles through Greenwich, England. This meridian is denoted 0 degree longitude. Longitudes on the equatorial circle are printed on the globe along the equator (or along the 10 degree South latitude line, depending on the globe you were given) in both directions from the Prime Meridian, increasing to the left as you view the globe as negative or Western (W) values and to the right as positive or Eastern (E) values until they meet in the central Pacific at 180 degrees. The 0 degree and 180 degree longitude lines divide the globe into the Eastern and Western Hemispheres. North America is in the Western Hemisphere. The story of accurate measurements of latitude and longitude is interesting. See for example, Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time by Dava Sobel.
Longitude and latitude specifically place locations. For example, the deepest point in the world ocean is 11,033 m (36,201 ft) below sea level located at approximately 11 degrees N and 142 degrees E in the Mariana Trench in the _________ Ocean. Mark and label this location on your globe. The island nearest this location is ______________ (U.S. Territory).
The global views of Greenland and Africa show that Greenland is actually [(much smaller) (about the same size) (much larger)] than Africa. This confirms that [(conformal) (equal-area)] maps more realistically portray comparative sizes.
Hold your globe at about waist high in front of you so you can look down on the world from above the North Pole. Then turn the globe over and look down on the South Pole. The comparison shows that the Northern Hemisphere contains more [(land) (water)] surface than does the Southern Hemisphere. (However, both the Northern and Southern Hemispheres' surfaces are more water than land. No matter how you look at it, the Earth is a water planet!)
Go to online portion of investigation.
The following portion of the Investigation file (Current Ocean Studies) is delivered via the DataStreme Ocean website. Investigations are posted about noon Eastern time on Tuesdays (Current Ocean Studies A) and Thursdays (Current Ocean Studies B) of each week of the course.
Welcome to DataStreme Ocean. This is the first of two online portions of investigations, which will be available by early afternoon, Eastern Time, every Tuesday and Thursday during the course. We hope your use of current environmental information will become an engaging experience. We encourage your exploration of the DataStreme Ocean products from the website and the use of these materials in your classroom or school.
WELCOME BACK: Procedure continued from Investigations Manual, Investigation 1A.
In this investigation, we examine the Earth system approach of DataStreme Ocean as described in the following paradigm:
Earth is a complex and dynamic system with a surface that is more ocean than land. The ocean interacts continually with the atmosphere, geosphere, cryosphere, and biosphere by exchanging, storing, and transporting matter and energy.
By far the largest reservoir of water on the planet, the ocean anchors the global hydrological cycle - the ceaseless flow of both water and energy within the Earth system. As a major component of all other biogeochemical cycles, the ocean is the final destination of water-borne and air-borne materials.
The ocean's range of physical conditions and supply of essential nutrients provide a wide variety of marine habitats for a vast array of living organisms.
The ocean's great thermal inertia, radiative properties, and surface- and deep-water circulations make it a primary control of Earth's climate system.
Society impacts and is impacted by the ocean. Humans rely on the ocean for livelihood, commerce, natural resources, security, and to disperse waste.
Humankind's intimate relationship with the sea calls for continued scientific assessment, prediction and stewardship to achieve and/or maintain environmental quality and sustainability.
A. Ocean Interactions with Atmosphere and Geosphere
From the DataStreme Ocean Paradigm: "The ocean interacts continually with the atmosphere, geosphere, cryosphere, and biosphere by exchanging, storing, and transporting matter and energy."
Sensors onboard geosynchronous satellites observe the Earth system using visible solar radiation that shows land and ocean surfaces in varying shades of gray whereas clouds are bright white. Water bodies have a much higher heat capacity than land and intercept more incoming sunlight than opaque land surfaces because of its greater transparency. Consequently, ocean surface waters can store tremendous amounts of heat energy. This heat evaporates large quantities of water and warms the overlying atmosphere. Winds then distribute this heat around the globe.
Image 1 is the visible satellite view of Hurricane Lili as it came ashore in southern Louisiana on 3 October 2002 from the Gulf of Mexico.
The cloud swirl associated with Hurricane Lili covered a region [(a few) (hundreds of)] kilometers across. These clouds were also at least 16 km (10 mi) thick. The water content of the clouds associated with the hurricane was huge.
The immediate and primary source for this cloud water was the [(Pacific Ocean) (Gulf of Mexico)]. With Lili approaching the coast, its onshore winds pushed a wall of water over the low-lying coastal plain. This storm surge had a height of up to 3 m (12 ft) and destroyed some flood-control levees. When the hurricane made landfall, its circulation weakened as it moved away from its warm water energy source and over the rougher land surface. Nonetheless, rainfall produced by the moisture-rich system remained heavy even as winds slackened. Four to eight inches of rain fell over portions of Louisiana, Mississippi and Arkansas, causing extensive fresh-water flooding.
B. Human/Ocean Interactions
From the DataStreme Ocean Paradigm: "Society impacts and is impacted by the ocean. Humans rely on the ocean for livelihood, commerce, natural resources, security, and to disperse waste."
Image 2 is view of the area around Japan from the Defense Meteorological Satellite's nighttime low-light sensor. The Japanese islands arc across the view from lower left to upper right. The coast of Korea is along the left side and China is at the top. Bright white areas on the land are city lights. North is oriented diagonally to the upper right. (You might notice the almost complete darkness of North Korea and its coastal waters.)
Clusters of white dots in the Sea of Japan (left center of image) and in the Pacific Ocean east of the islands (right center) are lights at sea. Asian fishing fleets use lights at night to attract fish to their nets. The concentrations of sea-borne lights suggest that [(a few) (many)] fishing boats are employed in that area. For the people of these densely populated and mostly rugged lands, the ocean is a [(major) (minor)] source of food.
Place the answers to Investigation 1A and the above questions on the Investigations Response Form which will be available Thursday and linked from the DataStreme Ocean website. Directions for delivery of your weekly investigation will appear at the end of the Thursday online portion of Investigation 1B.
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