Is it snowing less?
Visualisaton of snow cover over UK

Back in the 90's I remember one particular winter in Edinburgh when I was starting University, next to Pollock Halls, and my god it snowed. It was like, proper Winter Wonderland stuff. Since then? Hmmphf. Similarly, I've been coming to Ronneburg in Germany since the early 2000's and remember some pretty fun times taking the sledge out. Recently? Not so much.

So, is it snowing less?

To be up-front, answering this question is a deliberate excuse to try to find free data from Satellites. It's not on the mainline of my Biscuits theme but it would be nice to have some freely-accessible Satellite data in the same way that Overture Maps is available for structured data sources. That is pretty-nice in that no login is required, and the data is available in a modern cloud-orientated way. So, same biases apply here.

I'd heard of a couple of things in this area: COG (Cloud-optimised GeoTIFF) and Zarr. In particular, for COGs, I'd heard about Copernicus Browser on the Georust Discord.

I had a fun play around with it including producing a little animation of weather over Ronneburg:

I had a few difficulties working out how to get data programmatically, so I switched to pursue Zarr data-sources instead.

Narrators Voice: As with many Spikes I'll probably look back on this and wonder why the hell I didn't take a short-cut. That's fine, spikes are as much for learning the longer ways round as for doing the most efficient one.

After much futzing about online I found esa-climate-toolbox which looked good for a couple of reasons:

  1. example notebooks implied it had Zarr data available
  2. it had reasonable docs

You can read the notebook for the details, but I ended up guessing that the dataset mentioning SNOW would be useful 🙂. It also looked like it contained the right sort of stuff:

From this dataset I was able to get the "SWE" (Snow Water Equivalent) for the Edinburgh and Ronneburg areas, as defined by bounding boxes from Overture Maps:

These each show the "raw" swe per day and then a rolling average over 365 days. So, is it snowing less? I am not a meteorologist but ... yes?

Regardless of analysis accuracy, it's nice seeing this data is available, and it has been an interesting couple of days of playing about with this stuff. I would have liked to also get access more directly from Rust, but not everything in the world has to be in Rust. Yet 😉.