Sonde Landing Calendars

Seattle-area sonde landings tracked by SondeHub, plotted by month, 2021-2023

Weather patterns change with the seasons. As prevailing winds change, so do the typical landing zones of radiosondes. To determine the best times of year for finding sondes, I created a tool that would draw a “map calendar”—12 small maps in a grid, one for each month of the year, showing the historical landing locations of sondes during that month.

In my home of Seattle, for example, sondes are hard to retrieve. The nearest launch site is Quillayute, about 100 miles (170km) west, with the Olympic forest in between. Sondes sometimes make it far enough east to be close to civilization, but often land in the ocean or deep in inaccessible parts of the Olympics.

The Seattle-area calendar makes it clear that this effect is seasonal. From June to September, sondes consistently land in the ocean or the forest. We can confidently plan not to spend time sonde-hunting during the summer here! The best months seem to be November to January.

Currently, this site only has a few example calendars. Coming soon will be an online generator that will plot a map-calendar for any part of the world you select. If you’re impatient, you can run the mapper yourself: the code is here.

The four examples available are: