scholarly journals Statistical Characteristics of Mesoscale Convective Systems Initiated over the Tibetan Plateau in Summer by Fengyun Satellite and Precipitation Estimates

2021 ◽  
Vol 13 (9) ◽  
pp. 1652
Author(s):  
Xidi Zhang ◽  
Wenqiang Shen ◽  
Xiaoyong Zhuge ◽  
Shunan Yang ◽  
Yun Chen ◽  
...  

In order to investigate the key characteristics of mesoscale convective systems (MCSs) initiated over the Tibetan Plateau (TP) in recent years and the main differences in circulation and environmental factors between different types of MCSs, an automatic MCS identification and tracking method was applied based on the data from China’s Fengyun satellite and precipitation estimates. In total, 8820 MCSs were found to have been initiated over the TP during the summers from 2013 to 2019, and a total of 9.3% of them were able to move eastward out of the TP (EO). The number of MCSs showed a monthly variation, with a maximum in July and a minimum in June, while most EOs occurred in June. Compared with other types of MCSs, EOs usually had a lower cloud-top temperature, a greater rainfall intensity, a longer life duration, more rapid development, larger areas of rainfall and convective clouds, longer tracks and a wider influence range, indicating that EOs are more vigorous than the other types of MCSs. The movement of MCSs is mainly due to the mid- to high-level dynamic conditions, and moisture is an essential factor in their development and maintenance.

2021 ◽  
Vol 22 (1) ◽  
pp. 23-41
Author(s):  
Yanan Meng ◽  
Jianhua Sun ◽  
Yuanchun Zhang ◽  
Shenming Fu

AbstractHourly blackbody temperature data from the warm seasons (May–September) of 2009–18 were used to detect mesoscale convective systems (MCSs) generated in the southwest mountain area (elevation ≥ 500 m) of China. A total of 3059 MCSs were grouped into four categories (C1, C2, C3, and C4) according to their generation positions using K-means clustering. Major characteristics of the four types of MCSs and their synoptic environmental conditions were investigated. The MCSs had a peak in July and a minimum in May, and usually lasted from 3 to 21 h. The C1 MCSs generated in the northeast of the Tibetan Plateau developed faster, were largest, and had a longer lifespan. The C2 and C4 MCSs had greater intensity and were initiated in the southeast of the Tibetan Plateau and the west of the Yungui Plateau, and near the Wuling and Xuefeng Mountains, respectively. The C3 MCSs initiated in the Qinling, Ta-pa, and Wushan Mountains were smallest. The C1 and C2 MCSs contributed more than 30% to total precipitation, which was more than the C3 and C4 MCSs (<25%), and the contribution rate of MCSs to short-duration heavy rainfall affected by local MCSs was over 60%. Composite synoptic circulations of the four types of MCSs showed several factors, including the locations and intensities of cyclones in the Bay of Bengal and high pressure in the Indochina Peninsula in the low-to-middle troposphere, and vortexes or southwesterly winds in the low-level troposphere, regulate the location and intensity of convection.


2012 ◽  
Vol 93 (11) ◽  
pp. 1713-1724 ◽  
Author(s):  
Kristen L. Rasmussen ◽  
Robert A. Houze

Flash floods on the edge of high terrain, such as the Himalayas or Rocky Mountains, are especially dangerous and hard to predict. The Leh flood of 2010 at the edge of the Himalayan Plateau in India is an example of the tragic consequences of such storms. The flood occurred over a high mountain river valley when, on three successive days, diurnally generated convective cells over the Tibetan Plateau gathered into mesoscale convective systems and moved off the edge of the Plateau over Leh. An easterly midlevel jet associated with a midlevel monsoon vortex over northern India and a high over Asia helped the convection organize into propagating mesoscale systems that moved over the edge of the Plateau. On the third day the mesoscale system moving off the plateau was greatly invigorated when it suddenly drew on moisture flowing upslope over the terrain. It gained maximum strength from this intake of moisture near Leh, and the heavy rains washed over the surrounding mountains and down and over the town.


2021 ◽  
Vol 13 (21) ◽  
pp. 4289
Author(s):  
Yang Li ◽  
Yubao Liu ◽  
Yun Chen ◽  
Baojun Chen ◽  
Xin Zhang ◽  
...  

The spatiotemporal statistical characteristics of warm-season deep convective systems, particularly deep convective systems initiation (DCSI), over China and its vicinity are investigated using Himawari-8 geostationary satellite measurements collected during April-September from 2016 to 2020. Based on a satellite brightness temperature multiple-threshold convection identification and tracking method, a total of 47593 deep convective systems with lifetimes of at least 3 h were identified in the region. There are three outstanding local maxima in the region, located in the southwestern, central and eastern Tibetan Plateau and Yunnan-Guizhou Plateau, followed by a region of high convective activities in South China. Most convective systems are developed over the Tibetan Plateau, predominantly eastward-moving, while those developed in Yunnan-Guizhou Plateau and South China mostly move westward and southwestward. The DSCI occurrences become extremely active after the onset of the summer monsoon and tend to reach a maximum in July and August, with a diurnal peak at 11–13 LST in response to the enhanced solar heating and monsoon flows. Several DCSI hotspots are identified in the regions of inland mountains, tropical islands and coastal mountains during daytime, but in basins, plains and coastal areas during nighttime. DCSI over land and oceans exhibits significantly different sub-seasonal and diurnal variations. Oceanic DCSI has an ambiguous diurnal variation, although its sub-seasonal variation is similar to that over land. It is demonstrated that the high spatiotemporal resolution satellite dataset provides rich information for understanding the convective systems over China and vicinity, particularly the complex terrain and oceans where radar observations are sparse or none, which will help to improve the convective systems and initiation nowcasting.


2006 ◽  
Vol 16 (2) ◽  
pp. 116-121
Author(s):  
Zhong-yang Guo ◽  
Xiao-yan Dai ◽  
Jian-ping Wu ◽  
Hui Lin

Sign in / Sign up

Export Citation Format

Share Document