The LARGE group operates a suite of probes to measure in-situ cloud microphysical properties. Probes are typically mounted at an under-wing or wing-tip position in unperturbed air. The package of probes can be tailored to specific science objectives or mounting-point availability considerations. The following probes are available:
CAPS (Cloud, Aerosol, Precipitation Spectrometer), Droplet Measurement Technologies. The CAPS contains individual sensors. The CAS (Cloud Aerosol Spectrometer) measures size distributions of clouds and aerosols between 0.5-50µm diameter using forward-scattered light intensity from a 658nm laser. Response is calibrated with glass beads. The CIP (Cloud Imaging Spectrometer) measures size distributions of droplet and precipitation particles between 15-150µm diameter recording shadows on an optical array. The CIP is calibrated using a spinning disk. A hotwire is also used to measure total liquid-water-content. Each probe utilizes a local measurment of airspeed, temperature, and static pressure for quantification and has de-icing capability.
CDP (Cloud Droplet Probe), Droplet Measurement Technologies. The CDP measures droplet and aerosol size distributions between 2-50µm diameter using forward-scattering from a 658nm laser. The probe is calibrated with glass beads and has de-icing capability.
WCM-2000 (Science Engineering Associates). Measures Liquid Water Content (LWC) using two independent hotwire elements, Total Water Content (TWC) using a scoop sensor, and an element oriented parallel with the airstream as a control to establish the background response at that specific airspeed, temperature, and pressure. Ice Water Content (IWC) is calculated as the difference between TWC and LWC. Each element operates by maintaining a constant temperature, and the current necessary to maintain that temperature is related directly with water content.
