Hence, even though polarimetry has been accepted by the atmospheric community as the means to extract more information from populations of aerosol and cloud particles, remarkably this technique has only recently begun being used to look at individual particles using in situ sensors. There were a number of attempts in the late 1960s and early 1970s to distinguish water droplets from ice crystals using polarization techniques but the community failed to take interest in the technology at that time.
The idea laid dormant until 2007 when several groups began developing polarimetry for use in ice nucleus counters, cloud chambers and in single particle optical spectrometers flown on aircraft.
This presentation will describe, with associated data examples, the polarimetric, single particle sensors that are in active use in aerosol and cloud research: the Cloud and Aerosol Spectrometer with Polarization (CAS-POL), the Aerosol Particle Spectrometer with Polarization Detection (APSPD), the Cloud Particle Spectrometer with Polarization Detection (CPSPD), the Backscatter Cloudprobe with Polarization Detection (BCPD) and the Spectrometer for Ice Nucleation (SPIN).
These five instruments have been deployed on numerous ground based and airborne field experiments since 2010 with results that are beginning to open new avenues in our understanding of aerosol and cloud processes.