Some Measured Ice Concentrations in Pacific Clouds

The Pacific Dust Experiment (PACDEX) provided an opportunity to measure ice concentrations in clouds at locations from near Japan to near the continental U.S. and at altitudes from near the surface to above 40,000 ft. Because the flights of the NSF/NCAR Gulfstream-V sought to track pollution and dust events originating in China, aerosol conditions also varied greatly in regard to concentrations of total, dust, black carbon, and sulfate aerosol. The flights included studies of several frontal systems in cyclonic storms over the Pacific. This paper documents representative ice concentrations as encountered during this project, using measurements from a new (2D) hydrometeor probe modified to operate at Gulfstream-V flight speeds and to handle the associated higher data rates, and shows how such ice concentrations depend on altitude, temperature, distance from Asia, association with aerosol properties, and nature of the cloud systems.