Snow in Yellowstone
There were a selection of incredible photos of Yellowstone National Park last weekend with the environment covered in snow in mid-June. The article mentioned that this wasn’t actually a surprise given the variable weather that the region attracts in nearly every month of the year. However, I still think that snow shouldn’t be common place in June even if it can happen.
I was interested enough to load up an area of Yellowstone in Sentinel Explorer to have a look for myself. Both the 12th of June 2019 and 12th of June 2018 had relatively little cloud cover as Sentinel 2 flew past which makes for a great comparison.
The short-wave infrared picks up particular areas of high moisture content which could be attributed to snow on the ground even if it’s on the higher ground.
However, the explorer allows us to go a little further with the Normalised Difference Snow Index (NDSI). This does take into account moisture more generally, and often misinterprets water bodies, the red allows you to more easily see the potential snow across the landscape.
The NDSI is based upon a number of bands with values over 0.42 regarded as snowy (B3-B11)/(B3+B11)
Snow this time of year isn’t perhaps as uncommon as one article and a few pictures might make out. I guess it attracts a few interested eyes that are more than surprised when they hear of snow in June. (As was I)
Considering how much effort was involved visualising different wavelengths during various remote sensing workshops at uni, I’m always impressed by how far web-based technologies can go to visualise the Earth’s surface. I’ve put some links below for those interested in where the images came from.
If you’re interested in finding out more about remote sensing such as this, the Polar Geospatial Center are well worth a follow:
I just wanted to have a little play with the images and don’t know nearly as much as this lot. For 280 characters on similar topics follow me over on Twitter:
Useful links
The above article contains all my own views, not that of friends, family or my work. All satellite images from Sentinel 2 shown are accessed with respect of the Copernicus Open Access Hub licence.
