Tutorial: Using the Data Viewer

This tutorial will show you how use the Viewer to explore the data sets available on this web site. Examples will walk you step-by-step through the use of the Viewer interface to manipulate data and view it as maps or cross sections/profiles. The lower frame on this page shows the data catalog and provides access to the Viewer, allowing you to carry out the instructions given in the tutorial.

Examples


An Oceanographic Example

Global views

For this exercise, scroll down the data catalog to the Oceanographic Data section (or simply select Oceanographic Data from the list of categories). Here you will find a listing of annual, monthly, and seasonal Levitus94 data which provides global measurements of a variety of oceanographic parameters.

You have a number of data sets to choose from, but for this exercise you should select the seasonal Levitus temperature data. This link will bring you to a global map displaying LEVITUS94 seasonal temperature data for a specific time of year. [To find the source(s) of the data set click on the "references" button at the top left of the page.]

Clicking on the map will allow you to explore the data using the Viewer. Note the "Mar" at the end of the title on the Viewer page; this tells you you are looking at seasonal temperature data for the month of March. By manipulating the options given on the Viewer page you can choose how to display the data set. You can change the longitude (X), latitude (Y), vertical dimension (Z), or time (T) for which the data is displayed. You can view the data as either a colored or contoured map. Scroll down to the pop-up menu below "domain," select "plaincolor" or "plaincontour," and click on the "redraw" button to the right of the map. Try both map options.

Since no oceanographic data exists on the continents, they are filled in black. If you wish, you can change the continental representation by scrolling to the right until you see a pop-up menu labeled "draw" (just above the "help" button). If you want only continental outlines select "draw coast". If you want no continents select "none." [Note: "draw land" is currently selected and displays black continents.] After making your selection, click the "redraw" button. From now on as you go forward the continents will appear as you have designated. If you move back you will have to specify your choice again.

At this point you have a screen that is either a colored or contoured map of sea surface temperature for the month of March with continents filled in or outlined.

Depth views

You maybe interested in a map of temperature at some depth, say a thousand meters. You can obtain this by clicking the desired depth on the "Depth [m]" scale below the colored "Temperature" scale. When you explore the ocean by looking at a variety of depths you will see the formation of cold Antarctic bottom waters in the deeper depth views, the influence of Mediterranean water at the intermediate depth views, and the effect of upwelling in the shallower depth views. Take a look and then come back.

Seasonal views

Values of surface and near surface measurements vary seasonally so displaying these data by season reveals interesting information. To look at data for different times of the year click the desired month on the "Time" scale (below the "Depth[m]" scale) or type in the month or fraction of a month (0-11.99) to the right of the scale.

Regional views

To take a closer look at the data for a specific region of the ocean, you can zoom in from the default global view to a regional view. Scroll right and click on the "Zoom" pop-up menu to the right of the map. Select a X2 or X4 magnification and then click the map at the point you would like to have as the center of the enlarged view. You can continue to do this for successively larger regional views. Alternatively, you can type in, below the "Time" scale, the domain of your view by designating the width in degrees of longitude, the height in degrees of latitude, and the center as a position designated by a specific longitude and latitude.

Cross Sections or Profiles

At this time the Viewer can display E-W and N-S cross sections. In the near future it will be able to make cross sections of the data along any direction. To draw a north-south cross section through the ocean temperature data click the pop-up menu to the right of the map and select "YZ." Below this select "Flip Z." Now click on the map wherever you want to make the north-south section. The longitude you have chosen will appear at the top of the screen and the cross section will be drawn. The cross sectional data can be either colored or contoured. You can change between the two, as you do with the map view, by selecting plaincolor or plaincontour from the pop-up menu and then clicking "redraw." For an east-west cross section select "XZ" from the pop up menu and click on the map wherever you want to make the east-west section.


Geological Examples

  1. Topography/Bathymetry
  2. Global views

    For this exercise, scroll down the data catalog to the Geological Data section (or simply select Geological Data from the list of categories). Select ETOPO5 World Topography and Bathymetry. This link will bring you to a global map with colors designating elevations above and depths below sea level. [To find the source(s) of the data set click on the "references" button at the top left of the page.]

    Clicking on the map will allow you to explore the data using the Viewer. By manipulating the options given on the Viewer page you can choose how to display the data set. You can view the data as either a colored or contoured map. Scroll down to the pop-up menu below "domain," select "plaincolor" or "plaincontour," and click on the "redraw" button to the right of the map. Try both map options.

    You can re-color the map using your own choice of elevation intervals. First click on the "draw" pop-up menu and select "draw coast," then "redraw." Now click anywhere on the colored "Topography [m]" scale below the map. An outline map of the world will appear. Reset the color scale to go from -7000 to 8000. Set the first interval to be -7000 to -6000. Then click on a color from the color box below. The Viewer will fill in the first interval with the chosen color. The next interval will automatically be set 1000 meters higher than the previous one, but you can change it if you wish. Continue choosing colors for each interval up to 8000 and then click on "Finished." The Viewer will display your customized map.

    Regional views

    To take a closer look at the data for a specific region of the Earth, you can zoom in from the default global view to a regional view. Scroll right and click on the "Zoom" pop-up menu to the right of the map. Select a X2 or X4 magnification and then click the map at the point you would like to have as the center of the enlarged view. You can continue to do this for successively larger regional views. Alternatively, you can type in, below the "Topography" scale, the domain of your view by designating the width in degrees of longitude, the height in degrees of latitude, and the center as a position designated by a specific longitude and latitude.

    Cross Sections or Profiles

    At this time the Viewer can display E-W and N-S cross sections. In the near future it will be able to make cross sections of the data along any direction. Before you can make the cross sections you must first change the view of the data by selecting "oneline" from the pop up menu beneath the "Domain" box. Now scroll to the pop-up menu to the right of the map view and select "X" for an east-west cross section. Then either click on the map at the latitude at which you would like to draw the cross section, or click "redraw." If you click "redraw," the Viewer will draw an east-west cross section through the topography/bathymetry data at the equator. To draw a cross section at a different latitude click on the "Latitude" scale at the desired latitude or type the desired latitude in the box to the right of the scale and click on "redraw." The latitude you have chosen will appear at the top of the screen and the cross section will be drawn. To draw a north-south cross section select "Y" from the pop-up menu below the "redraw" button and then click on the "redraw" button. To change the longitude at which the cross section is drawn click on the longitude scale below the cross section or type the desired longitude in the box to the right of the scale and click on "redraw."

    To zoom in to a specific part of a cross section, perhaps a spreading ridge in an east-west cross section, you can either zoom in to the map view (following the instructions in the "Regional views" section above) before drawing the cross section, or you can zoom in after drawing the cross section by using the "Zoom" pop-up to the right of the cross section. Select a magnification from the pop-up menu and click on the plot at the longitude (or latitude in a north-south cross section) you would like to have as the center of the enlarged cross section. Alternatively, you can type in, below the "Latitude" (or "Longitude") scale, the domain of your cross section by designating the width in degrees of longitude (or latitude), and the center as a position designated by a specific longitude (or latitude).

    As an exercise, try the spreading ridge example mentioned above. Begin by making an east west cross section at 10° S latitude. Now select "X4" from the "Zoom" pop-up menu and click on the plot at 15° W longitude to center the new cross section at that longitude. You should now have an east west cross section at 10° S latitude, centered at approximately 15° W longitude, with a domain of 90 degrees of longitude. The Viewer shows a section of the mid-Atlantic ridge at 10° S latitude with continents to the far left and right of the view.

  3. Sediment thickness
  4. Global views

    For this exercise, scroll down the data catalog to the Geological Data section (or simply select Geological Data from the list of categories). Select Ocean Sediment Thickness. A colored map of the world will appear with colors designating varying thickness of ocean sediments. [To find the source(s) of the data set click on the "references" button at the top left of the page.]

    Clicking on the map will allow you to explore the data using the Viewer. By manipulating the options given on the Viewer page you can choose how to display the data set. You can view the data as either a colored or contoured map. Scroll down to the pop-up menu below "domain," select "plaincolor" or "plaincontour," and click on the "redraw" button to the right of the map. Try both map options.

    You can also designate the limits of the thickness scale by typing the desired thicknesses in the boxes to the left and right of the scale and then clicking "redraw."

    You can re-color the map using your own choice of thickness intervals. Click anywhere on the colored "Thickness [m]" scale below the map. A black and white map of the world will appear (the continents are black and all the data is white). Reset the color scale to go from 0.0000 to 13000. Set the first interval to be 0.0000 to 1000. Then click on a color from the color box below. The Viewer will fill in the first interval with the chosen color. The next interval will automatically be set 1000 meters higher than the previous one, but you can change it if you wish. Continue choosing colors for each interval up to 13000 and then click on "Finished." The Viewer will display your customized map.

    Regional views

    To take a closer look at the data for a specific region of the ocean, you can zoom in from the default global view to a regional view. Scroll right and click on the "Zoom" pop-up menu to the right of the map. Select a X2 or X4 magnification and then click the map at the point you would like to have as the center of the enlarged view. You can continue to do this for successively larger regional views. Alternatively you can type in, below the "Thickness [m]" scale, the domain of your view by designating the width in degrees of longitude, the height in degrees of latitude, and the center as a position designated by a specific longitude and latitude.

    Cross Sections or Profiles

    At this time the Viewer can display E-W and N-S cross sections. In the near future it will be able to make cross sections of the data along any direction. Before you can make the cross sections you must first change the view of the data by selecting "oneline" from the pop up menu beneath the "Domain" box. Now scroll to the pop-up menu to the right of the map view and select "X" for an east-west cross section. Then either click on the map at the latitude at which you would like to draw the cross section, or click "redraw." If you click "redraw," the Viewer will draw an east-west cross section through the thickness data at the equator. To draw a cross section at a different latitude click on the "Latitude" scale at the desired latitude or type the desired latitude in the box to the right of the scale and click on "redraw." The latitude you have chosen will appear at the top of the screen and the cross section will be drawn. To draw a north-south cross section select "Y" from the pop-up menu below the "redraw" button and then click on the "redraw" button. To change the longitude at which the cross section is drawn click on the longitude scale below the cross section or type the desired longitude in the box to the right of the scale and click on "redraw."

    To zoom in to a specific part of a cross section, you can either zoom in to the map view (following the instructions in the "Regional views" section above) before drawing the cross section, or you can zoom in after drawing the cross section by using the "Zoom" pop-up to the right of the cross section. Select a magnification from the pop-up menu and click on the plot at the longitude (or latitude in a north-south cross section) you would like to have as the center of the enlarged view. Alternatively, you can type in, below the "Latitude" (or "Longitude") scale, the domain of your cross section by designating the width in degrees of longitude (or latitude), and the center as a position designated by a specific longitude (or latitude).

Updated July 22, 2004
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