How to find snow levels using satellite imagery

Requested by mum

Up to date satellite imagery can be super useful for finding snow levels. Earth Explorer has a huge database available to the public. The Landsat imagery is pretty coarse (30m pixels), but quite frequent – so although you won’t be able to spot your neighbour’s dog shitting in your garden, you’ll probably be able to find a cloud free day to see recent large scale changes like landslides, avalanches, floods or snow levels.

How to

1. Go to USGS Earth Explorer, register for an account – here.

2. With the “Search Criteria” clicked, scroll to the area you want to see on the map, and click where you want imagery.

3. Enter some dates – for snow levels I usually do a month leading to today.

4. Click “Data Sets”

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5. Select which datasets you want – for recent imagery click ->Landsat Archive->Pre-Collection-> then tick L8 OLI/TIRS

6. Click “Results”

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You’ll get a list of imagery available with the most recent at the top, and the “Aquisition Date” shown

7. Click the little picture icon (Show Browse Overlay) and a sample low quality image will come up on the map.

8. If it has clouds, (like the one below) try the next image, and the next, until you find gaps in the clouds where you want to see.

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Like this one

9. Click the green down arrow icon (Download Options), you’ll need to log in to download.

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10. I usually download a LansatLook image with Geographic Reference. This outputs a zipped geotiff file. Unzipped, you’ll get three images. Choose the file that doesn’t end in ‘_QB.tif’ or ‘_TIR.tif’. (info on the images here)

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11. Open this image in Google Earth Pro (file->import), or any other GIS program and compare with a basemap to see where the snowline is. In Earth Pro moving the cursor around you’ll see altitude along with lat/long in the bottom of the screen. You’ll need to crop scale or super-overlay the image as you import it.

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