All-sky polarization imaging of cloud thermodynamic phase

Area of Science:

• Atmospheric Science
• Cloud Physics
• Remote Sensing

Background:

• Cloud thermodynamic phase (ice or liquid water) is critical for accurate climate modeling and weather forecasting.
• The S1 Stokes parameter, representing polarization differences, has been theoretically linked to cloud phase detection.
• Ground-based passive polarimetry offers a potential method for observing cloud properties.

Purpose of the Study:

• To experimentally validate the use of the S1 Stokes parameter for determining cloud thermodynamic phase.
• To assess the efficacy of a ground-based passive polarimeter for all-sky cloud phase detection.
• To compare polarimeter-derived cloud phase with data from a dual-polarization lidar.

Main Methods:

• Utilized an all-sky imaging polarimeter to collect observational data.
• Measured the S1 Stokes parameter from cloud observations.
• Employed a dual-polarization lidar for independent validation of cloud phase at the zenith.

Main Results:

• The study experimentally confirmed that the algebraic sign of the S1 Stokes parameter can detect cloud thermodynamic phase.
• The all-sky imaging polarimeter successfully provided continuous cloud phase information across the entire sky dome.
• Polarimeter measurements of zenith cloud phase showed good agreement with dual-polarization lidar data.

Conclusions:

• The S1 Stokes parameter method is a viable technique for experimentally determining cloud thermodynamic phase using ground-based passive polarimetry.
• All-sky passive polarimetry provides a valuable tool for cloud remote sensing, aiding climate and weather research.
• This method enhances our ability to understand cloud radiative properties and their role in Earth's climate system.