ATOC 5051

Introduction to Physical Oceanography, 2007

Assignment 1: Ready to Roll

Use Ocean Data View ( to access the Reid & Mantyla data set (available for download on the odv website).

This dataset contains >10,000 'casts' of a conductivity-temperature-pressure device. This device is usually mounted on a 'rosette' of automated water-capturing bottles and lowered from a ship that is holding position at the sea surface. The conductivity, temperature, and pressure are measured and can be used to find salinity and temperature as a function of depth. This dataset also has oxygen, silicate, phosphate, and nitrate, which were measured from the water samples taken from the automated bottles.

Your first opening of ODV will pop up ODV Quick Installation. No changes are necessary. You might want to make the temp directory blank, which will save some disk space.

Do File> Open. The Reid & Mantyla dataset is in My Computer/C:/Program Files/Ocean Data View (mp)/Ocean Data/Reid-Mantyla

The first thing you will see is a globe with all of the locations of the casts. Notice how sparsely sampled some regions are!

Description of the data is under Collection>View Info File.

Click on the Station tab at the bottom. You can now double click on any of the red dots on the map to see the data versus depth information for that cast. Clicking with the right mouse button will let you save a figure as a graphics file, clear the figures shown, zoom in on where you just clicked on the map, etc. The full range selector is useful if some of your data lies outside of the currently plotted range. Spend some time browsing through the oceans, and see what you find. You can also click on the depth versus variable plots to see the data values of individual points on the plot.

Click on the scatter tab at the bottom. This plots all of the casts currently selected in the map at the same time. It will take a little while if you have the global map selected, so zoom in on a region, e.g., the Mediterranean. Rather than just zooming in and out, you can use the Configuration>Selection Criteria to select sets of data for plotting. There are many more options there than are easily accessible by mouse. Configuration>Selection Criteria>Domain>Define Polygon is nice for making a polygon containing a set of data.

Now try out the Section tab at the bottom. A 'section' is what oceanographers call a plot that contours data versus the along-cruise distance and depth. Once you've got a mess of data, as here, section is more generally a property versus horizontal distance and depth contouring or shading. Experiment with defining sections. Notice that the data itself is often arranged in straight lines, this is because they are all casts from the same cruise.

Finally, try out the surface tab. This one takes some getting used to. In this dataset the main thing you'll want to do is change the z-variable by right clicking. You can then select a different depth, or select to plot salinity where temperature=6C, etc. Before you can change the z-variable, you've got to define what your new z-variable will be. You do this by going to Configuration>Iso-Surface Variables. Try defining salinity at depth=1000m. Then, you can change one of the plots on the canvas to show this by changing the z-variable to the 'salinity at depth=1000' you just defined. You can also do more subtle things, like plot temperature on a density surface (which is a good thing to do, we'll soon see!)

So, take a tour of this dataset, and find something you think is interesting, be it a region, a scatter of datapoints, or a comparison between different regions. Make a few figures demonstrating what you think, and write it up. The writeup should be a pdf file with figures included. You can verify that it isn't too long here.

If you are interested in using LaTeX, which is a great way to produce professional documents, I'll be distributing a LaTeX how-to at the next class. ProText, an easy to use version of LaTeX, is on the computers in the lab.


Good Luck!