| NPP/VⅡRS卫星反演青藏高原夏季对流云微物理特征 |
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| 引用本文： | 岳治国,余兴,刘贵华,戴进,朱延年,徐小红,惠英,陈闯.NPP/VⅡRS卫星反演青藏高原夏季对流云微物理特征[J].气象学报,2018,76(6):968-982. |
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| 作者姓名： | 岳治国 余兴 刘贵华 戴进 朱延年 徐小红 惠英 陈闯 |
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| 作者单位： | 1.陕西省人工影响天气办公室, 西安, 710014 |
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| 基金项目： | 第三次青藏高原大气科学试验——边界层与对流层观测（GYHY201406001）、国家自然科学基金中以国际合作项目（41561144004）。 |
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| 摘 要： | 青藏高原（下称高原）对东亚大气环流、气候变化及下游灾害性天气形成、发展有重要影响，研究青藏高原云微物理特征有重要意义。但因高原台站稀少，对云微物理研究不充分。NPP（National Polar-orbiting Partnership）卫星ⅦRS（Visible Infrared Imaging Radiometer Suite）传感器包含17个中分辨率通道（750 m）和5个高分辨通道（375 m），具有反演初生小块对流云的优势，能够利用NPP/ⅦRS反演对流云的微物理特征。利用NPP/ⅦRS卫星格点对流云云物理自动反演（Automatic Mapping of Convective Clouds，AMCC）软件对高原地区2013-2017年夏季（6-8月）过境的ⅦRS资料进行了反演，得到了高原对流云的宏、微观物理特征，并计算了这些物理量在0.33°×0.33°格点上的平均值。分析得出如下结论:（1）反演云底温度（Tb）与那曲探空计算抬升凝结温度（TLCL）线性相关，相关系数为0.87，均方根误差为3.0℃。（2）高原对流云宏、微观物理特征为:一是云底冷（Tb为-5℃），云底离地高度为1800-2200 m，云内含水量低；二是云底云凝结核数浓度（NCCN）为200-400个/mg，最大过饱和度（Smax）为0.7%，NCCN少，Smax大，云滴凝结增长速率更快；三是降水启动厚度（D14）小，为1500-2000 m，雅鲁藏布江流域及藏南地区D14约500-1000 m，更加容易形成降水；四是云顶海拔高度为10-13 km，云厚度从南部5000 m逐渐减小到北部2500 m，云厚有限；五是晶化温度高，从中部、南部-30℃到北部-25℃，加之高原Tb < 0℃，使得云内降水粒子以冰相为主。（3）高原对流云的这些微物理特征决定了其降水具有多发、短时、量小、滴大的特点。这些结论进一步深化了对高原夏季对流云的科学认识。
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| 关 键 词： | 青藏高原 ⅦRS 云微物理反演 对流云 云底温度 云凝结核 |
| 收稿时间： | 2018/3/13 0:00:00 |
| 修稿时间： | 2018/7/22 0:00:00 |
NPP/ⅦRS satellite retrieval of summer convective cloud microphysical properties over the Tibetan Plateau |
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| YUE Zhiguo,YU Xing,LIU Guihu,DAI Jin,ZHU Yannian,XU Xiaohong,HUI Ying and CHEN Chuang.NPP/ⅦRS satellite retrieval of summer convective cloud microphysical properties over the Tibetan Plateau[J].Acta Meteorologica Sinica,2018,76(6):968-982. |
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| Authors: | YUE Zhiguo YU Xing LIU Guihu DAI Jin ZHU Yannian XU Xiaohong HUI Ying and CHEN Chuang |
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| Institution: | 1.Office of Weather Modification of Shaanxi Province, Xi'an 710014, China2.Meteorological Institute of Shaanxi Province, Xi'an, 710016, China |
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| Abstract: | The Tibetan Plateau (TP) has important influences on the formation and development of the East Asian atmospheric circulation, climate change and disastrous weathers in its downstream regions. It is very important to understand the microphysical characteristics of clouds at the TP. However, observations and researches of the microphysical characteristics at this area are insufficient because of the sparse observation stations and few cloud physical data. ⅦRS (Visible Infrared Imaging Radiometer Suite) onboard the Suomi NPP (National Polar-orbiting Partnership) satellite, has an improved imaging spectroradiometer with seventeen channels of 750 m moderate resolution and five channels of 375 m image resolution. The high-resolution satellite has an advantage for observing the small or initial convective clouds. Based on the retrieval methodologies of cloud microphysical properties by NPP satellite were proposed, an automated mapping software package named AMCC (Automatic Mapping of Convective Clouds) has been developed to retrieve properties of convective cloud at the scale of satellite swath. The properties of convective clouds are automatically retrieved by AMCC and their values are averaged in 0.33°×0.33° grids via NPP/ⅦRS satellite data over the TP in the summers from 2013 to 2017. The results show that:(1) the temperature of lifting condensation level (TLCL) in Naqu meteorological station and the temperature of cloud base (Tb) from ⅦRS are linearly correlated with the correlation coefficient of 0.87 and the root-mean-square (RMS) error of 3.0℃; (2) convective clouds at the TP have the following microphysical properties. First, the cloud base temperature (Tb) is about -5℃, and the height of the cloud base above the ground (Hb) ranges between 1800-2200 m, and the cloud water content is small. Second, the cloud condensation nuclei concentrations (NCCN) is between 200 and 400 mg-1 with 0.7% of maximum supersaturation (Smax); consequently, the condensation growth rate of water cloud droplet with less NCCN and higher Smax is fast. Third, because the precipitation initiation depth (D14) varies within 1500-2000 m and 500-1000 m at the Yarlung Zangbo River Basin and the Zangnan region, respectively, and the clouds at these areas are more prone to precipitation. Fourth, the height of the cloud top above sea level (Htop) is between 10-13 km, but the cloud depth (Dcld) is rather small, which is about 5000 m at its southern part and gradually reduces to 2500 m at its northern part. Fifth, the glaciation temperature (Tg) ranges -30℃ at its central and southern parts to -25℃ at its northern part, which, combined with the high Tg and the Tb that is less than 0℃, lead to the domination of ice process in the clouds; (3) these microphysical properties of convective cloud at the TP explains why the precipitation is frequent and lasts over a short time with small amount and large rain drops. |
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