TY  - GEN
N2  - Snow microstructure is crucial for radia- tive transfer and mechanical interactions inside the snow cover and at the snow surface. The aim of this thesis is to determine which simplifications to general radiative trans- fer theory and to the true 3D snow microstructure can be assumed to still guarantee an adequate description of radiative transfer in snow. The analysis focuses on the optical properties reflectance and transmittance at near-infrared wavelengths and on the snow mi- crostructural parameters specific surface area (equivalent to snow grain size) and density. Three different approaches to radiative transfer are analyzed. They are characterized by (i) assuming an equivalent microstructure of a random collection of ice spheres with the same specific surface area and density as the true microstructure, (ii) ray tracing applied to the true microstructure or the equivalent microstructure and (iii) an asymptotic solu- tion for infinite snow blocks of the equivalent microstructure. Reflectance measurements can only be explained within the natural snow variability of 18% by a combination of models (i) and (ii) if the exact geometry of the compact measuring tool is implemented. Transmittance measurements of natural snow agree well with results for approach (i) and (ii). Only transmittance of highly anisotropic machine-made snow cannot be de- scribed by model (i). The results show that specific surface area and density are the two crucial properties that determine radiative transfer in snow. Finally, a combined high- resolution measurement method of these two microstructural parameters in the field is presented based on snow-profile photography.
A1  - Gergely, Mathias
TI  - Snow Characterization by Optical Properties
AV  - public
ID  - heidok12799
Y1  - 2011///
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/12799/
KW  - Schnee 
KW  -  Strahlungstransport 
KW  -  Reflexion 
KW  -  Transmissionsnow 
KW  -  radiative transfer 
KW  -  near-infrared 
KW  -  reflectance 
KW  -  transmittance
ER  -