Journal of the Meteorological Society of Japan. Ser. II
Online ISSN : 2186-9057
Print ISSN : 0026-1165
ISSN-L : 0026-1165
Micro-Physical Processes around Melting Layer in Precipitating Clouds as Observedby Vertically Pointing Radar
Takao TakedaYasushi Fujiyoshi
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1978 Volume 56 Issue 4 Pages 293-303

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Abstract

Micro-physical processes around melting layer in precipitating clouds were studied on the basis of quantitative observation by the use of a vertically pointing radar to the northern side of “Baiu” front on June 28, 1975, in Nagoya. Following three periods which are different in fine structure of radar echo and micro-physical processes were found out in travelling radar-echo system from the detailed analyses of vertical gradients of radar reflectivity factor. In period A, when a low laid on the front was about 1, 000km west-south-westward from Nagoya, it is not apparent whether there was breakup of snowflakes in the melting layer or not. In the region above melting layer, ice particles would have evaporated in some parts of this period. In the region below melting layer, the evaporation of raindrops would have been prevalent. In period B, when the low was about 700km south-westward, from Nagoya, it is inferred in the melting layer that the discrepancy in the type of ice particles above 0°C level would have resulted in the difference in aggregation activity of particles (snowflake formation) in spite of similar size distribution of them. In the region above melting layer, the accretion of supercooled droplets and/or the aggregation among ice particles would have occurred. In the region below melting layer, raindrops would have falled without remarkable growth or evaporation. In period C, when the low was about 500km south-south-westward from Nagoya, breakup of snowflakes would have occurred in the melting layer. In this period, the discrepancy of size distribution of particles above 0°C level is inferred to have caused the difference in aggregation activity in contrast with period B. In the region above melting layer, it is suggested that the accretion of supercooled droplets and/or the aggregation among ice particles would have occurred. In the region below melting layer, raindrops would have coalesced among them or captured cloud droplets.

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