Development of a handheld integrating sphere snow grain sizer (HISSGraS)

• Published in: Annals of Glaciology
• Main Authors: Teruo Aoki, Akihiro Hachikubo, Motoshi Nishimura, Masahiro Hori, Masashi Niwano, Tomonori Tanikawa, Konosuke Sugiura, Ryo Inoue, Satoru Yamaguchi, Sumito Matoba, Rigen Shimada, Hiroshi Ishimoto, Jean-Charles Gallet
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press
• Subjects: Snow metamorphosis; snow microstructure; snow/ice surface processes; Meteorology. Climatology; QC851-999; Annals of Glaciology
• Online Access: https://doi.org/10.1017/aog.2023.72; https://doaj.org/article/8c85fd7866824f748fe97b94379776b7

We developed a Handheld Integrating Sphere Snow Grain Sizer (HISSGraS) for field use to measure the specific surface area (SSA) of snow. In addition to snow samples, HISSGraS can directly measure snow surfaces and snow pit walls. The basic measurement principle is the same as that of the IceCube SSA instrument. The retrieval algorithm for SSA from reflectance employs two conversion equations formulated using spherical and nonspherical grain shape models. We observed SSAs using HISSGraS, IceCube and the gas adsorption method in a snowfield in Hokkaido, Japan. Intercomparison of the results confirmed that with HISSGraS direct measurement, SSA profile observations can be completed in just ~1/10 the time required for measurement of snow samples. Our results also suggest that HISSGraS and IceCube have similar accuracy when the same snow samples are measured using the same grain shape model. However, SSAs of near-surface snow layers measured using the three techniques exhibited some biases, possibly due to rapid snow metamorphism or melting during measurement and some technical issues with optical techniques. When excluding SSA data for the surface layer, which metamorphosed remarkably during measurement, IceCube- and HISSGraS-derived SSAs correlated strongly with those obtained by gas adsorption and HISSGraS accuracy is 21–34%.