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FENG Qiujuan, NIU Shengjie, HOU Tuanjie, et al. 2021. Aircraft-Based Observation of the Physical Characteristics of Snowfall Cloud in Shanxi Province [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 45(5): 1146−1160. doi: 10.3878/j.issn.1006-9895.2106.21004
Citation: FENG Qiujuan, NIU Shengjie, HOU Tuanjie, et al. 2021. Aircraft-Based Observation of the Physical Characteristics of Snowfall Cloud in Shanxi Province [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 45(5): 1146−1160. doi: 10.3878/j.issn.1006-9895.2106.21004

Aircraft-Based Observation of the Physical Characteristics of Snowfall Cloud in Shanxi Province

  • Based on observations from an aircraft that directly entered the snowfall cloud and MICPAS (Meteorological Information Comprehensive Analysis and Processing System), radar and satellite data, the macro and micro structure characteristics of a snowfall cloud in Shanxi Province on 29 November 2011, were analyzed. Notably, the radar echo of this snowfall process was mainly between 10 dBZ and 20 dBZ large stratiform cloud echo, inlaid with more than 30 dBZ massive and strong echo. The zero line of the radar radial velocity had a strong “S” curve with a bull’s eye structure. Strong vertical wind shear was observed from the lower level to the upper level. The liquid water content was mainly below 3.2 km, and the maximum value was 0.0697 g m−3. The ice and snow crystal number concentrations N50 (Number concentration of ice and snow crystals with particle diameter greater than 50 μm) and N200 (Number concentration of ice and snow crystals with particle diameter greater than 200 μm) and the ice water content were mainly produced in the upper part of the stratiform mixed-phase snowfall cloud, and the maximum values, which were 188.4 L−1, 33.5 L−1, and 0.121 g m−3, were obtained at approximately −9.3°C. From −14.4°C to −19.7°C, the images of ice crystals were mainly needle, columnar, and irregular, and the ice particles grew mainly by deposition. The images of ice and snow crystals at approximately −9.3°C were mainly dendritic and irregular. The aggregation, collision, and fracture of radial dendritic ice crystals may be the main reason for the high concentration of ice and snow crystals. The distribution of the ice and snow crystal spectra can be well fitted by the exponential form. The spectrum fitting parameters can be expressed by the power function Nos=1.021λ1.684 (Nos and λ represent intercept and slope, respectively. The larger Nos was, the higher the concentration of small particles was. The larger λ was, the higher the proportion of small particle number concentration to total particle number concentration was.), and the correlation coefficient R2 was 0.86. Three inversion times below 3.2 km were detected. The appearance of the inversion layer influenced the cloud microphysical characteristics, decreased the fitting parameter Nos, and inhibited the growth of rimming and deposition. As a result, the variation of the fitting parameters Nos and λ with temperature in this study was inconsistent with that in previous studies. The greater the inversion intensity was, the greater the inhibition effect.
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