Ice and water content of stratiform mixed-phase cloud

✍ Scribed by German Vidaurre; John Hallett

• Book ID: 104565110
• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 812 KB
• Volume: 135
• Category: Article
• ISSN: 0035-9009
• DOI: 10.1002/qj.440

✦ Synopsis

Abstract

Spatial characterization and probability distribution of particles in stratiform mixed‐phase clouds in the temperature range 5 to −45 °C were investigated based on 81 hours of flight on the NCAR C‐130 during the Alliance Icing Research Study II. Cloud particles were video‐recorded impacting on the optical window of a cloudscope, and Liquid Water Content (LWC) and Ice Water Content (IWC) derived from measurements of the power to evaporate particles of different size, shape and density collected by the T probe constant temperature sensors. Data were recorded at 1 Hz for a resolution of 130 m. Transitions between liquid, glaciated and mixed‐phase regions were sharp; frequent supercooled liquid regions lasted less than 2 seconds (<260 m), while less frequent mixed‐phase and glaciated regions persisted between 2 and 300 seconds (0.26 to 39 km) along the aircraft track. LWC, IWC and Total Water Content (TWC) were measured in concentrations up to 1.25, 0.45 and 1.25 g m^−3^ with an uncertainty of ∼0.02 g m^−3^. The IWC/TWC ratio showed two maxima at mostly liquid (<0.1) and mostly ice (>0.9); mixed‐phase corresponded to about 40% of the measurements. The large T probe showed mixed‐phase clouds with ice fraction less than half at temperatures below −20 °C, while the small T probe measured higher ice proportion, suggesting that ice was present in the form of preferentially collected small particles. At high temperatures (>−15 °C) ice and water were measured in concentrations up to 0.2 and 0.6 g m^−3^ respectively; at temperatures below −20 °C they were both measured in concentrations up to 0.3 g m^−3^. Copyright © 2009 Royal Meteorological Society