Data analysis concepts and observational methods
Plotting Map of Average of Properties Between Two Surfaces
Example 6E: Plotting Map of Average of Properties Between Two Surfaces
JOA can also calculate the average of any parameter between two surfaces. Sometimes this is useful when one is trying to visualize distributions of an identifiable layer of water.
Here we will look at the distribution of the weighted mean oxygen concentration between 250 and 750 decibars in the WOA05_NorthAtlantic_square.joa data file.
Files that may be needed or created in this example:
Continue from 6E-01:
- Calculations → Station Parameters → Integration
- Set up the Station Integration Calculations panel for a calculation of the weighted mean of O2 (dissolved oxygen) with respect to PRES (pressure) from 250 to 750 decibars over each profile as shown below:
- Click OK, the result will appear in the Data Window
- With the open Orthographic Map Plot in the foreground, bring up the Configure Map Plot dialog box:
- Double-click or control-click on a map plot
- Or type [ctrl/cmd]-R or Edit → Edit: plotname when a map plot is the front-most window
- Select the Station calculation values sub-panel of the Station Colors panel
- A list of all available station calculations will be shown. Select INT(O2-PRES,250.0-750.0)-td and then select the O2-global_cbr.xml color bar, as shown below:
- Click OK to get this updated plot:
This plot provides a clear illustration of the ventilation (oxygenation) of the Northern North Atlantic Ocean from the Labrador Sea and the Nordic Seas, with high oxygen waters spreading away from these regions. Note also the oxygen minima in the tropics, cut through in the equatorial zone due to the effects of equatorial upwelling.