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First simultaneous measurement of vertical air velocity, particle fall velocity, and hydrometeor sphericity in stratiform precipitation: Results from 47 MHz wind‐profiling radar and 532 nm polarization lidar observations
Author(s) -
Mega Tomoaki,
Yamamoto Masayuki K.,
Abo Makoto,
Shibata Yasukuni,
Hashiguchi Hiroyuki,
Nishi Noriyuki,
Shimomai Toyoshi,
Shibagaki Yoshiaki,
Yamamoto Mamoru,
Yamanaka Manabu D.,
Fukao Shoichiro,
Manik Timbul
Publication year - 2012
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/2011rs004823
Subject(s) - sphericity , lidar , wind speed , scattering , radar , depolarization ratio , atmospheric sciences , altitude (triangle) , precipitation , materials science , environmental science , geology , computational physics , optics , physics , meteorology , geometry , telecommunications , mathematics , computer science , composite material
Results from simultaneous measurements of vertical air velocity ( W ), particle fall velocity, and hydrometeor sphericity in stratiform precipitation are reported for the first time. Cases of stratiform precipitation on 8 (case A) and 16 December 2008 (case B) observed at Sumatra, Indonesia (0.2°S, 100.32°E), are described. A 47 MHz wind‐profiling radar measured W and reflectivity‐weighted particle fall velocity relative to the air ( V Z ) simultaneously. Upward W above ∼6.0 km altitude in case B (>0.2 m s −1 ) was greater than in case A (<0.1 m s −1 ). V Z at 300 m above the 0°C altitude in case B (1.8 m s −1 ) was greater than in case A (1.3 m s −1 ). The thickness of melting layer (ML) in case B (900 m) was greater than in case A (300 m). Because the large‐sized aggregates contribute to produce greater V Z and thicker ML, it is likely that entangled growth of dendritic crystals under the presence of significant upward W and enhanced aggregation occurrence by the well‐developed dendritic crystals produced the large‐sized aggregates. Lidar measured an increase of linear depolarization ratio ( δ ) and lidar dark band in the ML. Volume δ of raindrops was 0.08–0.10 in case B and close to zero in case A. Stronger multiple scattering in case B is likely a cause that produced the greater δ. In case B, a dip of δ was measured at the bottom of ML. The decrease of hydrometeor nonsphericity at the final stage of melting explains the dip.