Dual-polarization airborne lidar observations of polar stratospheric cloud evolution

• Main Authors: Poole, L. R., Mccormick, M. P., Kent, G. S., Hunt, W. H., Osborn, M. T.
• Format: Other/Unknown Material
• Language: unknown
• Published: 1990
• Subjects: 46; Arctic
• Online Access: http://ntrs.nasa.gov/search.jsp?R=19900041428

Dual-polarization 0.532 micron lidar data show systematic polar stratospheric cloud (PSC) evolution along a portion of the Airborne Arctic Stratospheric Expedition DC-8 flight of January 31, 1989. This flight leg was roughly aligned with air parcel motion on isentropic surfaces from 400-500 K, where the local adiabatic cooling rate was about 20 K/day. Type 1 PSCs show low depolarization ratios and scattering ratios which approach intermediate limiting values as ambient temperature decreases. These data suggest that Type 1 particles formed by rapid cooling may be nearly spherical and are restricted in size by partitioning of a limited HNO3 vapor supply among many competing growth sites. Type 2 PSCs appear at temperatures below estimated local frost points with increases in depolarization and scattering typical of larger ice crystals.