| 黄兆楚,王朝晖,周学思,印佳楠,孙啸申,彭敏,张晓瑞,杨文霞.张家口地区一次长时间降雪过程的滴谱特征分析[J].沙漠与绿洲气象,2022,16(5):70~77 |
| 张家口地区一次长时间降雪过程的滴谱特征分析 |
| Characteristic Analysis of Particle Size Distribution During a Snowstorm in Zhangjiakou |
| 投稿时间：2021-06-07 修订日期：2021-12-13 |
| DOI：10.12057/j.issn.1002-0799.2022.05.010 |
| 中文关键词: OTT激光雨滴谱仪 雪滴谱 下落速度 Gamma分布 |
| 英文关键词:OTTParsivel Snow drop spectrum Particle velocity Gamma distribution |
| 基金项目:河北省气象与生态环境重点实验室开放研究基金（Z202003Z）；河北省重点研发计划项目（20375402D）和河北省省级科技计划（19275420D）共同资助 |
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| 中文摘要: |
| 本文利用OTT Parsivel2激光雨滴谱仪和站点加密观测资料，对2019年11月29日张家口地区一次长时间降雪天气过程的滴谱演变特征进行了初步分析，本次降雪先后经历开始阶段、雪花阶段、稳定强降雪阶段、结束阶段。结果表明：（1）总体上，降雪天气过程中微物理参量（降雨强度R、数浓度Nt、雨水含量W、雷达反射率因子Z、质量加权平均直径Dm）演变趋势基本相同，其中开始阶段、稳定强降雪阶段、结束阶段的降水强度、雨水含量、雷达反射率因子受粒子数浓度影响较大，而雪花阶段降水强度、雨水含量、雷达反射率因子受粒子直径影响较大。（2）稳定强降雪阶段，粒子数浓度Nt量级为103至104，而Dm小于1 mm，这是由于大雪片在温度较低的情况下，下落过程中破碎形成大量小雪片。降雪过程中，雪滴下落速度小于2 m/s的粒子数占总粒子数的90%，强降雪阶段的雪滴下落速度集中于1~1.5 m/s。（3）分别使用二、三、四阶矩和最小二乘法对不同降雪阶段粒子谱进行Gamma分布拟合，在降雪过程中，最小二乘法拟合效果优于二、三、四阶矩方法。 |
| 英文摘要: |
| A snowstorm was well recorded on November 29, 2019 in Zhangjiakou and the spectrum characteristics of this weather was analyzed based on OTT Parsivel2 (Particle Size and Velocity Spectrometer) data and intensive observations. This snowstorm was categorized into four stages, including the beginning stage, snowflake stage, stable snowfall stage and the ending stage. The results are as follows: (1) In general, the evolution trend for all microphysical parameters (rainfall intensity R, number concentration Nt, rainfall content W, radar reflectivity factor Z, mass weighted average diameter Dm) is nearly identical during the whole snowfall process. In the snowflake stage, precipitation intensity, rainfall content and radar reflectivity factor are all greatly affected by particle number concentration. However, in the rest snowfall process, the particle diameter takes the responsibility for those changes above. (2) During the stable heavy snowfall stage, the particle number concentration (Nt) varies from 103 to 104, but the Dm is less than 1 mm, which may be caused by the shattering of falling large snowflakes under the circumstance of low temperature. In the process of snowfall, 90% particles were falling at a rate of less than 2 m/s, while at the stable snowfall stage the falling velocity of snow particles was mostly ranging around 1~1.5 m/s. (3) The second, third, fourth moment and the least square method were both used to fit the Gamma distribution of the particle spectrum distribution in different snowfall stages. In the process of snowfall, the least square method has better fitting results than the second, third, fourth moment. |
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