TY - JOUR
T1 - Observation of particle fall velocity in cirriform cloud by VHF and millimeter-wave Doppler radars
AU - Yamamoto, Masayuki K.
AU - Ohno, Yuichi
AU - Horie, Hiroaki
AU - Nishi, Noriyuki
AU - Okamoto, Hajime
AU - Sato, Kaori
AU - Kumagai, Hiroshi
AU - Yamamoto, Mamoru
AU - Hashiguchi, Hiroyuki
AU - Mori, Shuichi
AU - Hashiguchi, Noriko O.
AU - Nagata, Hajime
AU - Fukao, Shoichiro
PY - 2008/6/27
Y1 - 2008/6/27
N2 - In this study, it is demonstrated that a combination of VHF and millimeter-wave Doppler radars is a key tool for observing particle fall velocity in cirriform clouds. VHF (47-MHz) and millimeter-wave (95-GHz) Doppler radars observed cirriform clouds at West Sumatra, Indonesia (0.2°S, 100.32°E) from 2000 LT 14 to 0800 LT 15 November 2005. Radar reflectivity factor (Ze) observed by the 95-GHz radar showed that echoes from cloud particles had tops around 12-14 km and bottoms around 8-10 km. Doppler velocity observed by the vertically pointed beam of the 95-GHz radar (Vair+Z) was compared with vertical air velocity (Vair) observed by the 47-MHz radar to confirm that Vair+Z, a sum of Vair and reflectivity-weighted particle fall velocity (VZ), showed consistent changes with Vair and hence VZ is able to be retrieved by subtracting Vair from Vair+Z. The correlation coefficient between VZ and Ze in the middle part of clouds (10.5-12.2 km) was -0.81, which was higher than that (-0.47) in the bottom part (7.2-10.5 km). The change of VZ for Ze in the middle part was larger (Ze = -31.9 VZ - 32.2) than that in the bottom part (Ze, = -90.2 VZ - 71.8). These results suggest that particle size was a dominant factor that determined Ze in the middle part. Using VZ, median volume diameter (D0) was estimated to suggest that D0 was larger than ∼70 μm in the bottom part and ranged from ∼40 μm to larger than ∼106 μm in the middle part.
AB - In this study, it is demonstrated that a combination of VHF and millimeter-wave Doppler radars is a key tool for observing particle fall velocity in cirriform clouds. VHF (47-MHz) and millimeter-wave (95-GHz) Doppler radars observed cirriform clouds at West Sumatra, Indonesia (0.2°S, 100.32°E) from 2000 LT 14 to 0800 LT 15 November 2005. Radar reflectivity factor (Ze) observed by the 95-GHz radar showed that echoes from cloud particles had tops around 12-14 km and bottoms around 8-10 km. Doppler velocity observed by the vertically pointed beam of the 95-GHz radar (Vair+Z) was compared with vertical air velocity (Vair) observed by the 47-MHz radar to confirm that Vair+Z, a sum of Vair and reflectivity-weighted particle fall velocity (VZ), showed consistent changes with Vair and hence VZ is able to be retrieved by subtracting Vair from Vair+Z. The correlation coefficient between VZ and Ze in the middle part of clouds (10.5-12.2 km) was -0.81, which was higher than that (-0.47) in the bottom part (7.2-10.5 km). The change of VZ for Ze in the middle part was larger (Ze = -31.9 VZ - 32.2) than that in the bottom part (Ze, = -90.2 VZ - 71.8). These results suggest that particle size was a dominant factor that determined Ze in the middle part. Using VZ, median volume diameter (D0) was estimated to suggest that D0 was larger than ∼70 μm in the bottom part and ranged from ∼40 μm to larger than ∼106 μm in the middle part.
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U2 - 10.1029/2007JD009125
DO - 10.1029/2007JD009125
M3 - Article
AN - SCOPUS:50049116036
SN - 0148-0227
VL - 113
JO - Journal of Geophysical Research
JF - Journal of Geophysical Research
IS - 12
M1 - D12210
ER -