Cloud and Precipitation Particle Identification Using Cloud Radar and
Lidar Measurements: Retrieval Technique and Validation
Abstract
This paper describes a technique for identifying hydrometeor particle
types using airborne HIAPER Cloud Radar (HCR) and High Spectral
Resolution Lidar (HSRL) observations. HCR operates at a frequency of 94
GHz (3 mm wavelength), while HSRL is an eye-safe lidar system operating
at a wavelength of 532 nm. Both instruments are deployed on the NSF-NCAR
HIAPER aircraft. HCR is designed to fly in an underwing pod and HSRL is
situated in the cabin. The HCR and HSRL data used in this study were
collected during the Southern Ocean Clouds, Radiation, Aerosol Transport
Experimental Study (SOCRATES). Comprehensive observations of the
vertical distributions of liquid and mixed-phase clouds were obtained
using in-situ probes on the aircraft and remote sensing instruments.
Hydrometeor particle types were retrieved from HCR, HSRL, and
temperature fields with a newly-developed fuzzy logic particle
identification (PID) algorithm. The PID results were validated with
in-situ measurements collected onboard the HIAPER aircraft by a
2D-Stereo (2D-S) cloud probe. Particle phases derived from the PID
results compare well with those obtained from the 2D-S observations and
agree in over 70 % of cases. Size distributions are also consistent
between the two methods of observation. Knowledge of the particle type
distribution gained from the PID results can be used to constrain
microphysical parameterization and improve the representation of cloud
radiation effects in weather and climate models.