Intellectual Merit: Measurements of cloud condensation nuclei (CCN), soot mass and cloud particle concentration, size and shape will be conducted as part of the Ice in Clouds-Layer Experiment (ICE-L), and soot mass only for the PACific Dust EXperiment (PACDEX). These measurements will be made with the Droplet Measurement Technologies continuous-flow streamwise thermal-gradient CCN counter, the single particle soot photometer (SP-2) the Cloud Aerosol Spectrometer (CAS) and the Cloud Imaging Probe (CIP). The airborne measurements of CCN will be correlated with those made on the ground at a high altitude location in the Rocky Mountains. The measurements of soot will be made in cloud-free air, cloud interstitial air and cloud particle residuals. The freezing state of supercooled water droplets smaller than 50 microns will be derived from the forward to backscattering ratios measured with the CAS.
The measurements will contribute to the accomplishment of a number of the objectives described in the ICE-L and PACDEX science overview documents; determine which heterogeneous ice nucleation modes are active and important by detecting the initial formation of ice particles in clouds, measurement of ice particle size, concentration and bulk condensed water properties over short spatial scales, identify which aerosol particles are active as ice nuclei and characterize the physical and chemical properties of the ice nucleating particles.
Broader Impacts: The study involves collaboration between a private company that specializes in instruments for measuring cloud and aerosol particle properties and university researchers and students who specialize in the analysis and interpretation of measurements made with these instruments. The research will address cloud radiation issues critical to climate sciences.
