Graphics Options in Giovanni
6.1 Color Palette Options
The Area Plot and Hovmöller Plot output options in Giovanni provide three different color palette options: Pre-defined, Dynamic, and Customized.
The Pre-defined color option is the color scale that is commonly used with the data by the data provider. In the case of ocean color data, the Pre-defined color scale option is a logarithmic scale, allowing visualization of the full range of data values in the data set. The North Atlantic Ocean area plot shown on the previous page uses the Pre-defined color option:
The Dynamic color scale option selects a linear color palette range that spans the entire range of values existing in the region that was selected. This may not work well for data with a wide range of values, as shown below. However, for data with a fairly narrow range of values, the Dynamic option can be very effective.
Because there are a few areas in the region with high values, this color palette was selected, but because most of the data is below 5.0 mg m-3, these higher values are hard to detect.
The third option is the Customized color palette, which allows the user to select the range of values for the color scale. In some cases, the Customized option can be used to duplicate a color scale selected by the Dynamic option for other time periods or regions.
The image shown below shows how the Customized option can be used to highlight data within a selected range of values, using the selection of Minimum and Maximum values shown above.
In this case, the color scale allows excellent visualization of the variability of the data with values ranging between 0.1 and 2.0 mg m-3.
6.2 Y-Axis Scaling Options
There are two Y-axis scaling options for Time Plots in Giovanni, Dynamic and Customized. The Dynamic option chooses the Minimum and Maximum values for the Time Plot Y-axis (dependent variable) based on the values generated by the mean value calculation for the selected region. The Customized optionallows the user to select the Minimum and Maximum values and the Y-axis scale intervals. This option is particularly useful to produce multiple time plots with different data ranges on the same scale, allowing easy comparison.
The Customized Y-axis option is demonstrated above, for the same region used to generate the time plot shown on the Selection Functions page, which used the Dynamic option. The two plots are shownbelow to demonstrate the difference between these two options.
Dynamic Option Y-axis scaling
Customized Option Y-axis scaling