Open Access Thesis
Snow mechanics; Snow--Iowa--Remote sensing;
Snow is unstable under natural environmental conditions; it undergoes metamorphism that can be measurable with an energy flux model. The demand for snow research is increasing due to its importance for maintaining Earth’s energy balance and hydrological applications. Snow metamorphism is a process of transformation of snow particles with an expense of surface free energy. Very few studies have been completed on snow metamorphism in grassland, cropland and barren surfaces that needs farther investigation. In this study, an attempt was made to measure winter snow metamorphism with physical based model and detecting snow metamorphism by using hyperspectral imaging spectroradiameter in grassland, cropland and barren surfaces.
The questions proposed in this research were: Can snow metamorphism be estimated from a ground based investigation using physical properties of snow across cropland, grassland and barren surface? Do the characteristics of snow metamorphism vary between cropland, grassland and barren surface?Can ground based hyperspectral imaging detect differences in snow metamorphism characteristics between cropland, grassland and barren surface?
The instruments used to collect field data on snow physical properties in this research were ASD FieldSpec 3 Spectroradiometer, Fluke 561 IR Thermometer, gridded mesh cards of various size, ruler, portable weighing scale, graduated measuring cylinder and magnifying glass respectively. The study indicated that by considering physical properties of snow such as, snow grain size; snow surface temperature; snow depth and snow volume coupled with meteorological parameters like, wind speed; air temperature; atmospheric pressure and temperature at dew point derived from weather station on different days at specific time period used in an energy flux model, it is possible to measure snow metamorphism across cropland, grassland and barren surfaces. The results further showed that snow metamorphism characteristics such as: estimated amounts of snowmelt and snow grain size varied during different field days in different land types which indicate an increase – decrease in snowpack cold content respectively. Mean estimated amounts of snowmelt in grassland, cropland and barren surface found were 0.065 mm/day, 0.066 mm/day and 0.061 mm/day respectively. Diverse weather phenomenon altered the characteristics of snow metamorphism in different land types observed from this study. Results of statistical analysis with different methods showed there was no significant difference in the amounts of snow melt between three different land types under study.
Reflectance of snow from hyperspectral imaging device showed difference in spectral signatures from different land types for different snow grain size on particular field day in specific time. After comparing all the snow reflectance spectra from three land types, the grassland showed the highest snow reflectance followed by cropland and barren surface which had the lowest snow reflectance according to different grain size on particular field day during specific time. Beside this, when PCA was applied to the combined datasets collected during different dates with ASD FIeldSpec 3 spectroradiometer it revealed components 1 and 2 with the following hyperspectral bands with component loading > 0.9: 1014.5, 1024.5, 1034.5 and 355, 356, 374.5 and 394.5 nm at wavelength range between 350nm –1039nm bands were important for identifying snow metamorphism characteristics .
Additional instances of snow metamorphism were observed from this study such as, icy structures in three different land classes on a particular day with varied amounts of snow melt and grain sizes that require further investigation. During icy condition the estimated amounts of snow melt found in three different land types as, cropland: 0.0536 (mm/day); grassland: 0.0544 (mm/day) and barren surface: 0.0491(mm/day) having snow grain size .5mm, 1mm and 2mm respectively.
This study provided valuable insights about snow surface energy balance regulation and its effect on seasonal snow metamorphism in cropland, grassland and barren surfaces respectively. The importance of hyper spectral imaging spectroradiometer in detecting snow metamorphism was determined. Snow spectral libraries were created according to grain size, which can serve as future references for corresponding studies on snow metamorphismin three different land classes under study respectively
Year of Submission
Master of Arts
Department of Geography
Andrey Petrov, Chair
1 PDF file (ix, 121 pages)
©2020 Ayan Sasmal
Sasmal, Ayan, "A ground based investigation of snow metamorphism using an energy flux model and hyperspectral imaging across cropland, grassland and barren surface in northeast Iowa" (2020). Dissertations and Theses @ UNI. 1063.