Part 3—Retrieve and Graph Buoy Data

Step 1 –
Request Water Temperature Data for Buoy B01

Now that you know some of the basics about phytoplankton blooms and you've seen the types of data that are available from buoys, you'll set up several data requests. You'll request your data reports as graphs and use them to predict the spring phytoplankton bloom for 2009. Using a year that has already passed will allow you to check your prediction against reality.

Recall that the "ideal" conditions for plankton growth include sunlight, and nutrients from the deeper water. You will want to look for signs of recent mixing due to changes in water temperature brought on as the seasons change from winter to spring, and again from late summer to fall. You will be looking for water that is relatively warm, but has not yet stratified, which isolates the upper-level waters from the nutrient-rich deeper waters. Ideal date ranges for phytoplankton blooms are March - June and August - October.
  1. Click the Graphing /Download Icon in the middle-right of the NERACOOS home page page to access the Historical Data Graphing and Download Page.
  2. Or, choose Data & Tools > Historical Data from the top navigation menu and select the first listed link Graphing and Download to access the data request interface. Both options are highlighted below.

    3. select historical graphing tab

    By examining water temperature, salinity, and density at various depths for several buoys, you will be able to infer when the water column at each location is mixed or stratified, an important condition for a plankton bloom. The first location you'll examine is Buoy B, a near-shore buoy located northeast of Portsmouth, New Hampshire.
  3. On the page that opens, click the Data Types tab, and select Water Temperatures from the pull-down list.
    • Specify: Weekly Average and select the Unit: Degrees Centigrade.
    • Click the Add Data Type button. You will see the Data Type is now listed in the right column and you will receive a confirmation message "Data type added!" in green, and the data will now show up in the upper-right corner.
  4. Click the Time Periods tab and set the time period. You only need to do this step once for all the buoys.
    • Check the radio button labeled Custom time (UTC) and set the time period to March 1, 2009 to October 31, 2009.
    • Click the Add Selection button.
  5. You will see that the Selected Time Period is now showing in the right-hand list.
  6. Click the Locations tab and then click the checkbox next to the Western Maine Shelf Buoy (B01). To acquire all the temperature data from different depths, keep all the default selections that NERACOOS has marked.
  7. At the bottom of the list, click the Update Selection button. You now are ready to produce a graph of the data that you selected.

Step 2 –
Graph the Water Temperature Data for Buoy B01

  1. To request the data from the buoy you've selected, click the Report tab or the Create report now button.
  2. NERACOOS offers several output format options. For the purposes of this chapter, choose the Graph option (the default). Then, click the View Report Now! button, you will receive a confirmation message in a pop-up window.
    create report



    3. The screen on the confirmation window will be blank briefly while NERACOOS assembles the data, although it will give you a status message. Teaching Note: if you are doing this with a large class, it may take a while. As a teaching strategy, you may want to assign each team a different buoy. There are 6 buoys that are of interest: (A01, B01, D02, E01, I01, M01). Once the data has been downloaded, saved and printed, it can be shared among the class.

    graph produced


    To save the graphs as images, place your cursor over the graph, right-click (PC) or control-click Mac, and choose Save Image As... Save each graph with a descriptive name. For example, you might save this first file as "Buoy_BO1_water_temp.jpg".

Step 3 –
Retrieve and Graph Density and Salinity Data for Buoy B01

Set the water temperature graph aside for a moment. Set up requests and generate graphs of density and salinity data for the same location, Buoy B01. Since the time period will stay the same, you only need to change the data type.
  1. Click the Data Types tab and click the remove all link to clear your previous request.
  2. Select Density and Salinity from the pull-down list. Specify Weekly Average as the time step.
  3. Click the Report tab and the View Report Now! button to graph density as a function of water depth.

  4. Graph the data, then print, or save, the graph.

Step 4 –
Retrieve and Graph Water Temperature, Density, and Salinity Data for Other Buoys

Repeat the steps above to obtain water temperature, density, and salinity data for 2009 for A01, B01, D02, E01, I01, M01. Generate graphs of these data and save the graphs. When finished, you should have 12 plots: 2 graphs (water temperature on one and salinity and density on the other) for each for the 6 buoy locations. Special Note for Buoy M: Buoy M has multiple depths available. Select only the 1 meter, 2 meter (where applicable), 20 meter, and 50 meter depths.
For teaching purposes—In the event the GoMOOS server was not operational or too slow, sample graphs from 2004 are displayed on this linked page. (This collection does not include A or D, however). Sample Water Temperature, Salinity, and Density Graphs