The Acancia meets Hurricane 7 of 1893

To more closely examine encounters of particular vessels and hurricanes would benefit greatly with being able to run the voyage and hurricane layers through time, as I can with my ArcMap version of the GIS. While I cannot upload time enabled files to the free version of ArcGIS Online, NOAA has published HURDAT on ArcGIS Online as a map service and as a Web map. The map service is served from the following URL: http://maps4.arcgisonline.com/ArcGIS/rest/services/A-16/NOAA_Hurricane_Tracks-Temporal/MapServer, and anyone can therefore add it as a layer to their Web map using the free ArcGIS Online viewer and display the data through time using the temporal function.

That is what I have done experimentally in the below Web map, reducing the voyages to that of the Acancia in order to simplfy the map during the trial. To add such layers, select Add Data, Add Layer from the Web, and then type the URL for the service into the dialog box. After being added to the Web map, the time control, or "time slider,"  for the NOAA layer appears at the bottom of the map frame. In the version embedded in this blog, select the time button and the time slider will appear as a separate window.

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The problem is that it does not work well because of the enormous amount of data. The HURDAT layer in my ArcMap GIS, which covers the North Atlantic for 1851-1900, has 9366 records. The NOAA map service includes Pacific and Atlantic storms, 1851-2011. When running the time sequence, the rendering takes so long that blobs of hurricane tracks, indistinguishable from one another, jerk across the screen.

I tried filtering the layer to reduce the amount of data being displayed, which is also possible in ArcGIS Online for layers from a map service. I selected each sub-layer in turn, selected filter, and set the Hurricane Season field to 1893, which was the year the Acancia was crossing the North Atlantic in August. Then I set the controls for the time slider to display only 1893 and do it in 365 equal intervals to get a daily interval. Even at an extent, or "time window," of one year, however, the time function does not work well enough to use because the symbols take so long to render that they remain essentially static.

Even the data in the pop-up boxes for the hurricane symbols take a long time to arrive from the server compared to those for the Acancia. Nonetheless, the pop-ups do reveal that the Acancia, shortly after turning southward, had a near encounter with a category 2 hurricane in mid Atlantic on August 26, 1893.

In the next post, I will try another strategy to visualize discrete hurricane-vessel encounters.