Eshelman, Laura M.Tauc, Martin J.Shaw, Joseph A.2019-04-232019-04-232019-02Eshelman, Laura M., Martin Jan Tauc, and Joseph A. Shaw. "All-sky polarization imaging of cloud thermodynamic phase." Optics Express 27, no. 3 (February 2019): 3528-3541. DOI:10.1364/OE.27.003528.1094-4087https://scholarworks.montana.edu/handle/1/15469Knowing the cloud thermodynamic phase (if a cloud is composed of ice crystals or liquid droplets) is crucial for many cloud remote sensing measurements. Further, this knowledge can help in simulating and interpreting cloud radiation measurements to better understand the role of clouds in climate, weather, and optical propagation. Knobelspiesse et al. [Atmos. Meas. Tech. 8, 1537 (2015)] showed that, for simulated zenith observations, the algebraic sign of the S1 Stokes parameter (related to the difference between perpendicular and parallel linear polarization in the scattering plane) can be used to detect cloud thermodynamic phase when observed with a ground-based passive polarimeter. In this paper, we describe the use of our all-sky imaging polarimeter to experimentally test this proposed method of detecting cloud thermodynamic phase in the entire sky dome. The zenith cloud phase was validated with a dual-polarization lidar instrument.enCC BY: This license lets you distribute, remix, tweak, and build upon this work, even commercially, as long as you credit the original creator for this work. This is the most accommodating of licenses offered. Recommended for maximum dissemination and usehttps://creativecommons.org/licenses/by/4.0/legalcodeArticle