王改利,周任然,扎西索郎,刘黎平. 2021. 青藏高原墨脱地区云降水综合观测及初步统计特征分析. 气象学报,79(5):841-852. DOI: 10.11676/qxxb2021.054
引用本文: 王改利,周任然,扎西索郎,刘黎平. 2021. 青藏高原墨脱地区云降水综合观测及初步统计特征分析. 气象学报,79(5):841-852. DOI: 10.11676/qxxb2021.054
Wang Gaili, Zhou Renran, Zhaxi Suolang, Liu Liping. 2021. Comprehensive observations and preliminary statistical analysis of clouds and precipitation characteristics in Motuo of Tibet Plateau. Acta Meteorologica Sinica, 79(5):841-852. DOI: 10.11676/qxxb2021.054
Citation: Wang Gaili, Zhou Renran, Zhaxi Suolang, Liu Liping. 2021. Comprehensive observations and preliminary statistical analysis of clouds and precipitation characteristics in Motuo of Tibet Plateau. Acta Meteorologica Sinica, 79(5):841-852. DOI: 10.11676/qxxb2021.054

青藏高原墨脱地区云降水综合观测及初步统计特征分析

Comprehensive observations and preliminary statistical analysis of clouds and precipitation characteristics in Motuo of Tibet Plateau

  • 摘要: 为加深对雅鲁藏布大峡谷水汽通道入口处云和降水三维结构及微物理特征的认识,在第二次青藏高原综合科学考察研究专题和国家重点研发计划项目的支持下,中国气象科学研究院于2019年在西藏墨脱地区建立了野外观测试验基地,开展了水汽、云和降水的综合观测,先后布设了先进的Ka波段云雷达、微波辐射计、X波段双偏振相控阵雷达、降水现象仪、K波段微雨雷达等设备,获取了高时、空分辨率的云和降水的宏、微观数据。文中简单介绍了此次观测的情况,并利用云雷达2019年的观测数据和降水现象仪2019年6月至2020年6月的观测数据对云的宏观特征及雨滴谱特征进行了统计分析。从云的宏观特征来看,该地区云的发生率较高,云廓线占2019年云雷达观测廓线的67%,降水云廓线占总云廓线的45%。旱季和雨季云底高度的频率分布在垂直方向均有两个高值区,分别为0—1 km和2—3 km,且超过40%的云底高度低于1 km,这可能是墨脱降水云较多造成的。接近60%的云顶高度在4—7 km。总的来说,墨脱地区以中云和低云为主,云通常在下午到晚上形成,早上到中午慢慢消散;从雨滴谱分布特征来看,该地区平均的雨滴谱谱宽和大雨滴的浓度随雨强的增大而增大,降水以中、小粒子为主,中、小粒子浓度超过粒子数浓度的99%。对流云降水的特点是粒子直径较小,而数浓度较高。粒子质量加权平均直径(Dm)的范围在1.0—1.6 mm(平均1.38 mm),标准化截距参数(lgNw)的范围在3.6—4.5(平均4.01),表现出海洋性对流降水的特征。此外,该地区降水的lgNw呈现双峰特征,分别对应于对流云和层状云降水。

     

    Abstract: In order to better understand the three-dimensional structure and microphysical characteristics of clouds and precipitation at the entrance of the water vapor transport channel in Yarlung Zangbo Grand Canyon, the Chinese Academy of Meteorological Sciences established a field campaign base in Motuo in 2019 under the support of the Second Tibetan Plateau Scientific Expedition and Research Program and the National (Key) Basic Research and Development Program of China. Motuo is located at the southeastern Tibet Plateau (TP). Advanced X-band dual polarization phased array radars, Ka band cloud radars, K band micro radars, precipitation phenomenometers, and microwave radiometers are used to carry out comprehensive observations of water vapor, clouds and precipitation. One of the specific scientific goals of the campaign is to obtain a better understanding of cloud and precipitation microphysical processes and improve the parameterization scheme of the cloud-precipitation microphysical processes in numerical models. Based on cloud radar data collected for the period from January to December 2019 and precipitation phenomenometer data for the period from June 2019 to June 2020, the macroscopic characteristics of clouds and raindrop spectrum characteristics are statistically analyzed. The macroscopic characteristics of clouds indicate that the occurrence frequency of clouds in this area is relatively high, accounting for 67% of cloud radar profiles in 2019, and precipitation clouds account for 45% of the cloud cover. Occurrence frequency of cloud base height (CBHs) in both dry and rainy seasons experienced two peaks corresponding to heights of 0–1 km and 2–3 km, respectively. One striking feature is that more than 40% of the CBHs are lower than 1 km probably due to high occurrence frequency of precipitation clouds. Nearly 60% of the cloud top heights (CTHs) are between 4 and 7 km. In general, the vertical frequency distributions of CBHs and CTHs indicate that low- and mid-level clouds prevailed in Motuo during the observational period. Clouds tended to form most frequently from the afternoon to the evening and slowly dissipate from the morning to the noon time. In terms of the raindrop spectrum characteristics, the average raindrop spectral width and number concentration of large drops increased with rainfall intensity. The combination of small- and mid-size drops dominated precipitation in Motuo, and their contributions exceeded 99% of the number concentration. Convective precipitation in Motuo is identified to be maritime-like precipitation and characterized by a large normalized intercept parameter lgNw = 3.6–4.5 (with a mean value of 4.01) and small mass-weighted mean diameter Dm = 1.0–1.6 mm (with a mean value of 1.38 mm). Furthermore, the characteristic bimodality of lgNw was observed in Motuo, corresponding to convective and stratiform precipitation.

     

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