Multi-variate temporal analysis is another area in which time maps provide a clearer and more understandable visual representation of complex data. For example, several environmental factors must be considered when analyzing algae blooms. Such factors include sea surface temperature, sea surface salinity, air temperature, precipitation, stream flows, tidal height difference, upwelling, and wind speed. Individually, these factors do not have much of an impact on whether or not an algae bloom will occur. Instead, the factors must be analyzed as a whole which can be a troublesome task.
How can one recognize the windows of opportunity for these algae blooms? As noted before, traditional 2D and 3D views fall short for this type of task. Cue in Dr. Koehler’s time maps.
The first step is to display each environmental factor as a time map. In the example of the algae bloom, seven different environmental time maps will be created. Second, a binary filter is applied to the data that highlights days with favorable conditions for an algae bloom. A value of one equals days with favorable conditions and a value of zero equals days that are not favorable for an algae bloom. The binary filter is also displayed as a time map.
For example, one environmental factor is stream flow. Flows less than 350 cubic meters/second are favorable for an algae bloom. By viewing the binary color relief, one can quickly pinpoint when stream flows are less than 350 cubic meters/second. These typically occur between August and October. One can also see in a drought occurred in 2001 resulting in less than normal stream flows for the months of January through April. All days represented in black are favorable stream flow conditions for an algae bloom.