Analysis of QualitySpec Trek Reflectance from Vertical Profiles of Taiga Snowpack

Abstract

Snow microstructure is an important factor for microwave and optical remote sensing of snow. One parameter used to describe it is the specific surface area (SSA), which is defined as the surface-area-to-mass ratio of snow grains. Reflectance at near infrared (NIR) and short-wave infrared (SWIR) wavelengths is sensitive to grain size and therefore also to SSA through the theoretical relationship between SSA and optical equivalent grain size. To observe SSA, the IceCube measures the hemispherical reflectance of a 1310 nm laser diode from the snow sample surface. The recently developed hand-held QualitySpec Trek (QST) instrument measures the almost bidirectional spectral reflectance in the range of 350-2500 nm with direct contact to the object. The geometry is similar to the Contact Probe, which was previously used successfully for snow measurements. The collected data set includes five snow pit measurements made using both IceCube and QST in a taiga snowpack in spring 2017 in Sodankylä, Finland. In this study, the correlation between SSA and a ratio of 1260 nm reflectance to differentiate between 1260 nm and 1160 nm reflectances is researched. The correlation coefficient varied between 0.85 and 0.98, which demonstrates an empirical linear relationship between SSA and reflectance observations of QST.

Special Issue on Remote Sensing of Snow and Its Applications

“…Monitoring of snow extent and SWE requires solid knowledge of the physical properties of snow, high-quality instrumentation, and refined methods for calibration and interpretation of snow observations. Leppanen et al [29] presented an empirical linear relationship, on taiga snow, between specific surface area (SSA) and reflectance observations of recently developed hand-held QualitySpec Trek (QST) instrument. The microstructure of snow is an important parameter for the modeling of microwave emission and optical reflectance, and it is therefore also important for remote sensing applications.…”

“…The microstructure of snow is an important parameter for the modeling of microwave emission and optical reflectance, and it is therefore also important for remote sensing applications. The SSA is an important snow parameter for the modeling of microwave emission and optical reflectance, and is therefore also important for remote sensing applications [29]. Sanow et al [30] presented terrestrial laser scanner-(TLS) (resolution of +/−5 mm) derived surface geometry and vertical wind profile measurements to compare concurrent aerodynamic roughness length estimates for changing snow surface features of shallow snowpack.…”

An Ultra-Portable Vis-NIR Spectrometer with an Integrated Light Source for Chemometric Applications

“…A list of several miniaturized spectrometers reported during the last decade are available in the. [11][12][13][14][15][16][17][18][19][20][21] Although several spectrometers are small in size, they require external radiation sources that are mains-powered. This limits their usage on the field.…”