Study area
Study area
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Geology:
The Saas Fee region of Switzlerland is home to the Allalin glacier, among others, as well as high alpine peaks which maintain snowpack year round (Bolinger). These glaciated areas are at least 4000m (13,000ft) above sea level. From a geologic timescale perspective, the Swiss Alps are a fairly young mountain range at 44 million years old, and as still very tall and jagged as a result. The Alps are composed of many rock types, but a metamorphic rock called gneiss is the most common type (Schmid, 1996).
Climate:
The region of Saas Fee, Switzerland has a temperate to cold climate. In the winter, temperatures can regularly reach -15 C (5 F), and summer temperatures generally stay below 15 C (60 F). The region receives a heavy amount of precipitation especially during the summers with up to 10 inches per month. Winter months receive around 3 inches of precipitation (Climate-data.org).
Saas Fee region in 2013
Band combination: 5, 4, 2 (RGB)
Landsat 8
Image ID: LC09_L2SP_195028_20240915_20240916_02_T1
Saas Fee region in 2024
Band Combination: 5, 4, 2 (RGB)
Landsat 9
Image ID: LC09_L1TP_195028_20240915_20240915_02_T1
Band Combinations:
There are several different band combinations that can accentuate the differences between snow and the surrounding land cover. Snow reflects very highly in the visible and near-infrared (NIR) wavelength bands (researchgate indian article). Therefore, choosing bands that are in this part of the spectrum is important. A band combination of 5, 4, 2, highlights the snow and ice while clearly differentiating from the surrounding land cover.
Differentiating Snow and Clouds
Another study used an interesting band combination to differentiate between snow and clouds. I did not use this band combination because my images didn't have clouds near the study area. However, this band combination could be useful if it was necessary to use imagery with clouds. The band combination is 2, 6, 7 (RGB). Clouds reflect slightly more in the shortwave portion of the spectrum which is why this band combination utilitizes the shortwave bands 6 and 7 (Gaur, et al, 2022).
Snow is clearly visible and differentiated against the surrounding land cover, and represented in red. Clouds are represented as white. Image created in QGIS by Max Warnock
The reflectance properties of snow vs. clouds are different as seen in this graph. The band combination using shortwave bands helps to differentiate between the two (Park, et al, 2012).
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