New Voyager Area Statistics Tool
New Voyager Area Statistics ToolPosted October 17, 2017
Voyager now provides a utility for computing statistics over a user-selected area for gridded datasets, including satellite data, forecasts (weather, surf, tide, ocean), bathymetry, and land elevation. This tool computes the mean (average), median, minimum, maximum, and/or standard deviation for the displayed data overlay within a given bounding box on the map. While Voyager already provided the ability to query data at a particular pixel, this new tool is useful for gathering information over larger areas.
Where available, Voyager’s menu options now include a new “area statistics” sub-folder (shown below). After toggling this folder open, click “draw box” to initiate an area selection. Click twice on the map to select opposite corners of a bounding box. Clicking on the resulting center marker produces a pop-up window with the computed statistics. The speed with which these stats appear depends on the size of the area selected and the resolution of the underlying dataset. For temporal data, options are also provided for plotting and downloading time series of the area statistics over various time spans. The edges and corners of the bounding box can be further adjusted, and the center marker can be dragged to a new location. It is also possible to refine the vertices of the bounding box using the input boxes for specifying map coordinates in decimal degrees.
Voyager menu options shown below at bottom for selecting an area over which to compute WaveWatch III (WW3) surf forecast statistics:
Voyager screenshot of area statistics for wave height forecast around Hawaiʻi; unit conversions provided as well as checkboxes for selecting which statistics to plot or download:
Time series plot of area statistics for model wave height around Hawaiʻi showing mean (dark orange), standard deviation (light orange), min and max (gray) over the course of one month:
Time series plot of WRF Mariana Islands regional wind forecast around Saipan showing the predicted min/max range shaded in gray, increasing to nearly 40 knots and switching from westerly to easterly:
Rain forecast for Oʻahu’s south shore shows a dry spell until the following night:
When saving a link to the current Voyager map view (via the “link” button in the upper-right of the interface), the coordinates of the selected area are preserved in the URL allowing users to bookmark or share the computed area results.
Development of this new Voyager utility was funded by NOAA OceanWatch Central Pacific Node.