Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A smartphone-based sensor for measuring the optical properties of snow   Snow is a highly complex medium composed of from ice crystals of various
shapes and sizes. Knowledge of its intrinsic optical properties such as the
scattering and absorption coefficient is tantamount for radiative transfer
models in climate research. The absorption coefficient in particular allows us
to access information about light-absorbing particles contained in the snow. In
contrast to snow's apparent properties like the albedo, measuring the intrinsic
properties is challenging, Here, we present a simple apparatus that can measure
bulk optical properties of snow using readily available components and a
smartphone camera, and a robust diffuse-optical framework for data analysis. We
demonstrate the instrument both on scattering phantoms with known scattering
and absorption coefficient as well as in the field. Its low cost, simplicity
and portability uniquely qualify this setup for large-scale field work,
undergraduate education and citizen science.

5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn