14 Polarimetric Characteristics and Microphysical Structure of a Freezing Rain and Ice Pellet Event in the Kanto Area on 29 January 2016

Monday, 28 August 2017
Zurich DEFG (Swissotel Chicago)
Nobuhiro Nagumo, MRI, Tsukuba, Japan; and A. Adachi and H. Yamauchi

Handout (4.1 MB)

Freezing rain and ice pellets (liquid-core pellets) occurred on 29 January 2016 in the Kanto region of Japan. This event caused at least $1 million worth of damages to infrastructure and vegetation. This event was recorded simultaneously by several meteorological observatories and by the MRI advanced C-band solid-state polarimetric radar (MACS-POL) and 2D-video distrometer (2DVD), which enabled us to analyze the three-dimensional polarimetric characteristics and microphysics of the ice pellets based on operational sounding data and surface visual evidence. Local decrease of correlation coefficient (and differential reflectivity increase) at the altitude below the melting layer was detected by MACS-POL, which suggests the freezing of completely or partially melted snowflakes. The reports by meteorological observatories were ice pellets at that time. 2DVD also showed the characteristics of ice droplets (e.g., bulging or shattering). On the other hand, the circumference was supercooled rain. A coating of glaze upon the ground and tree branches were found in the subzero layer below the melting layer. Horizontal and vertical wind components were estimated using MACS-POL data by applying the VAD (Velocity Azimuth Display) method. This analysis suggested that the freezing of droplets corresponded to the divergence structure of the melting layer. In this presentation, the relation between ice pellets formation and environmental wind field will be discussed.
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