Title First experiments to determine snow density from diffuse near-infrared transmittance
Author Gergely, M.; Schneebeli, M.; Roth, K.
Author Affil Gergely, M., WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland. Other: Heidelberg University, Germany
Source Cold Regions Science and Technology, 64(2), p.81-86, ; International snow science workshop 2009, Davos, Switzerland, Sept. 27- Oct. 2, 2009, edited by J. Schweizer. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0165-232X
Publication Date Nov. 2010
Notes In English. Based on Publisher- supplied data GeoRef Acc. No: 309831
Index Terms density (mass/volume); grain size; measurement; models; snow; snow cover; spectra; density; near-infrared spectra; new methods; specific surface area; wave dispersion
Abstract Snow density is one of the key properties to characterize a snow cover. We present diffuse near-infrared transmittance measurements with an integrating sphere setup in the laboratory. We analyze 8 snow samples taken from melt forms, decomposed, rounded, faceted and machine made snow. Reference measurements of specific surface area (optically equivalent grain size) and density are done by micro-computed tomography and used as input for transmittance calculations. A diffuse flux extinction model cannot be applied to simulate transmittance as our setup cannot be approximated by an infinite snow block thickness. Calculations with a more intricate radiative transfer model (DISORT) agree with our measurements within the estimated grain size and density variability for all probed natural snow types. Only our machine made snow shows a morphology which cannot be modeled by DISORT. Thus, our results show for the first time a direct experimental correlation between transmittance and snow specific surface area and density without the need for an empirical fitting parameter. We feel this to be an important step towards a possible high- resolution, quantitative optical measurement method to determine snow density in combination with an independent specific surface area measurement.
URL http://hdl.handle.net/10.1016/j.coldregions.2010.06.005
Publication Type conference paper or compendium article
Record ID 65006934