title: Scattering properties of sands. 1. Comparison between different techniques of measurements.
abstract: Measuring linear polarization of light scattered by a cloud of particles can help retrieve their physical properties. We present an extensive study of polarimetric measurements of sand grains that can be found on the surface and in the atmosphere of the Earth. Different techniques of measurements are compared using the Laboratoire de Météorologie Physique nephelometer on the ground and the Propriétés Optiques des Grains Astronomiques et Atmosphériques on the ground and in microgravity during parabolic flights. The techniques used on the ground bias the measurements. When the grains are lifted by an air draft, differentiation is produced in the size distribution and the nature of the floating particles. When the grains are carried along with the airflow, some grains become oriented along the flow direction at air speeds greater than a few meters per second, producing abnormal negative polarization. On the other hand, measurements conducted under microgravity permit the retrieval of the representative optical properties of the lifted sand grains with sizes greater than tens of micrometers.
authors.affiliation: Laboratoire de Météorologie Physique, Université Blaise Pascal, Aubière, France. daugeron@moniut.univ-bpclermont.fr
authors.forename: Daniel
authors.initials: D
authors.lastname: Daugeron
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Renard
authors.forename: Bertrand
authors.initials: B
authors.lastname: Gaubicher
authors.forename: Benoît
authors.initials: B
authors.lastname: Couté
authors.forename: Edith
authors.initials: E
authors.lastname: Hadamcik
authors.forename: François
authors.initials: F
authors.lastname: Gensdarmes
authors.forename: Guillaume
authors.initials: G
authors.lastname: Basso
authors.forename: Corinne
authors.initials: C
authors.lastname: Fournier