Abstract:

To effectively improve the ability of forecast and early warning, disaster preventing and reducing, mesoscale convective complexes (MCC) occurring in the northeast side of Tibet Plateau were comprehensively analyzed during 2000-2015 from satellite cloud images, circulation situations, water vapor transport, cold advection effects, etc. The results showed that MCC appearing in the south of Qinling Mountains accounted for 66% of all processes during 2000-2015, and they mostly formed from the midnight to morning, while MCC occurring in the north of  Qinling Mountains accounted for 34%, and they mostly formed from the early evening to early morning. Before the generating of MCC, they mostly appeared in the northeast of SAH (south Asian high) on 200 hPa, the low vortex or shear line cooperated in the middle and lower troposphere over southern Gansu to eastern Sichuan, and the stable surface thermal low pressure controlled over eastern Sichuan and southern Shaanxi. The SAH and low vortex or shear accordingly moved eastward when MCC occurred, while the surface thermal low pressure moved northward and its northern cold high obviously moved southward at the same time. MCC in the south of Qinling Mountains mostly formed in the development of convection cells or the consolidation of convective cloud clusters, and the characteristics of the stretching northward and moving eastward for MCC were obvious. However, MCC in the north of Qinling Mountains mostly formed in the development of convective clouds in warm area at the front of cold front cloud system, and the moving eastward of MCC was significant. The heavy rain caused by MCC in the northeast side of Tibet Plateau often appeared in the maximum gradient side of TBB, the period of maximum hourly rainfall matched better with the lowest TBB.

Key words: the northeast side of Tibet Plateau, MCC, synthetic analysis, the southwest vortex, high level anticyclone circulation, surface cold front or cold advection

摘要：

从卫星云图、环流形势、水汽输送和冷平流作用等方面出发，对2000—2015年发生在青藏高原东北侧的中尺度对流复合体(MCC)进行综合分析，寻求该区域MCC特征，以有效提高该地区此类天气的预报、预警及防灾减灾服务能力。结果表明，2000—2015年，青藏高原东北侧MCC出现在秦岭南侧的占66%，多形成于后半夜；秦岭北侧的占34%，基本发生于傍晚至凌晨。MCC多出现在200 hPa南亚高压反气旋的东北侧；对流层中低层，甘南、四川东部地区有低涡或切变配合；地面上，四川东部及陕南多为稳定少动的热低压控制。MCC发生时，南亚高压、低涡或切变相应东移，地面热低压北移，其北侧的冷高压同步南压明显。秦岭南侧的MCC多以对流单体发展或对流云团合并加强形成，此类MCC北伸、东移特征明显；秦岭北侧的MCC多为冷锋云系前部暖区的对流云团发展形成，该类MCC东移特征明显。青藏高原东北侧MCC的强降水往往出现在TBB梯度最大一侧，最大小时降雨量与TBB最低时段匹配较好。

关键词: 青藏高原东北侧, MCC, 合成分析, 西南涡（武都涡）, 高空反气旋环流, 地面冷锋或冷平流