Dynamic Diagnosis of an Extreme Precipitation Event over the Southern Slope of Tianshan Mountains Using Multi-Source Observations
The southern slope of the Tianshan Mountains features complex terrain and an arid climate, yet paradoxically experiences frequent extreme precipitation events (EPEs), which pose significant challenges for weather forecasting. This study investigates an EPE that occurred from 20 to 21 August 2019 usi...
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MDPI AG
2025-04-01
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| author | Jiangliang Peng Zhiyi Li Lianmei Yang Yunhui Zhang |
| author_facet | Jiangliang Peng Zhiyi Li Lianmei Yang Yunhui Zhang |
| author_sort | Jiangliang Peng |
| collection | DOAJ |
| description | The southern slope of the Tianshan Mountains features complex terrain and an arid climate, yet paradoxically experiences frequent extreme precipitation events (EPEs), which pose significant challenges for weather forecasting. This study investigates an EPE that occurred from 20 to 21 August 2019 using multi-source data to examine circulation patterns, mesoscale characteristics, moisture dynamics, and energy-instability mechanisms. The results reveal distinct spatiotemporal variability in precipitation, prompting a two-stage analytical framework: stage 1 (western plains), dominated by localized convective cells, and stage 2 (northeastern mountains), characterized by orographically enhanced precipitation clusters. The event was associated with a “two ridges and one trough” circulation pattern at 500 hPa and a dual-core structure of the South Asian high at 200 hPa. Dynamic forcing stemmed from cyclonic convergence, vertical wind shear, low-level convergence lines, water vapor (WV) transport, and jet-induced upper-level divergence. A stronger vorticity, divergence, and vertical velocity in stage 1 resulted in more intense precipitation. The thermodynamic analysis showed enhanced low-level cold advection in the plains before the event. Sounding data revealed increases in precipitable water and convective available potential energy (CAPE) in both stages. WV tracing showed vertical differences in moisture sources: at 3000 m, ~70% originated from Central Asia via the Caspian and Black Seas; at 5000 m, source and path differences emerged between stages. In stage 1, specific humidity along each vapor track was higher than in stage 2 during the EPE, with a 12 h pre-event enhancement. Both stages featured rapid convective cloud growth, with decreases in total black body temperature (TBB) associated with precipitation intensification. During stage 1, the EPE center aligned with a large TBB gradient at the edge of a cold cloud zone, where vigorous convection occurred. In contrast to typical northern events, which are linked to colder cloud tops and vigorous convection, the afternoon EPE in stage 2 formed near cloud edges with lesser negative TBB values. These findings advance the understanding of multi-scale extreme precipitation mechanisms in arid mountains, aiding improved forecasting in complex terrains. |
| format | Article |
| id | doaj-art-e1da553fccfb41668342ec060c899d66 |
| institution | OA Journals |
| issn | 2072-4292 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | MDPI AG |
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| series | Remote Sensing |
| spelling | doaj-art-e1da553fccfb41668342ec060c899d662025-08-20T02:31:08ZengMDPI AGRemote Sensing2072-42922025-04-01179152110.3390/rs17091521Dynamic Diagnosis of an Extreme Precipitation Event over the Southern Slope of Tianshan Mountains Using Multi-Source ObservationsJiangliang Peng0Zhiyi Li1Lianmei Yang2Yunhui Zhang3Kuqa Meteorological Bureau, Kuqa 842000, ChinaXinjiang Key Laboratory of Oasis Ecology, College of Geography and Remote Sensing Sciences, Xinjiang University, Urumqi 830017, ChinaInstitute of Desert Meteorology, China Meteorological Administration, Urumqi 830002, ChinaXinjiang Meteorological Observatory, Urumqi 830002, ChinaThe southern slope of the Tianshan Mountains features complex terrain and an arid climate, yet paradoxically experiences frequent extreme precipitation events (EPEs), which pose significant challenges for weather forecasting. This study investigates an EPE that occurred from 20 to 21 August 2019 using multi-source data to examine circulation patterns, mesoscale characteristics, moisture dynamics, and energy-instability mechanisms. The results reveal distinct spatiotemporal variability in precipitation, prompting a two-stage analytical framework: stage 1 (western plains), dominated by localized convective cells, and stage 2 (northeastern mountains), characterized by orographically enhanced precipitation clusters. The event was associated with a “two ridges and one trough” circulation pattern at 500 hPa and a dual-core structure of the South Asian high at 200 hPa. Dynamic forcing stemmed from cyclonic convergence, vertical wind shear, low-level convergence lines, water vapor (WV) transport, and jet-induced upper-level divergence. A stronger vorticity, divergence, and vertical velocity in stage 1 resulted in more intense precipitation. The thermodynamic analysis showed enhanced low-level cold advection in the plains before the event. Sounding data revealed increases in precipitable water and convective available potential energy (CAPE) in both stages. WV tracing showed vertical differences in moisture sources: at 3000 m, ~70% originated from Central Asia via the Caspian and Black Seas; at 5000 m, source and path differences emerged between stages. In stage 1, specific humidity along each vapor track was higher than in stage 2 during the EPE, with a 12 h pre-event enhancement. Both stages featured rapid convective cloud growth, with decreases in total black body temperature (TBB) associated with precipitation intensification. During stage 1, the EPE center aligned with a large TBB gradient at the edge of a cold cloud zone, where vigorous convection occurred. In contrast to typical northern events, which are linked to colder cloud tops and vigorous convection, the afternoon EPE in stage 2 formed near cloud edges with lesser negative TBB values. These findings advance the understanding of multi-scale extreme precipitation mechanisms in arid mountains, aiding improved forecasting in complex terrains.https://www.mdpi.com/2072-4292/17/9/1521moisture transportdiagnostic analysisblack body temperaturemesoscale convective system |
| spellingShingle | Jiangliang Peng Zhiyi Li Lianmei Yang Yunhui Zhang Dynamic Diagnosis of an Extreme Precipitation Event over the Southern Slope of Tianshan Mountains Using Multi-Source Observations Remote Sensing moisture transport diagnostic analysis black body temperature mesoscale convective system |
| title | Dynamic Diagnosis of an Extreme Precipitation Event over the Southern Slope of Tianshan Mountains Using Multi-Source Observations |
| title_full | Dynamic Diagnosis of an Extreme Precipitation Event over the Southern Slope of Tianshan Mountains Using Multi-Source Observations |
| title_fullStr | Dynamic Diagnosis of an Extreme Precipitation Event over the Southern Slope of Tianshan Mountains Using Multi-Source Observations |
| title_full_unstemmed | Dynamic Diagnosis of an Extreme Precipitation Event over the Southern Slope of Tianshan Mountains Using Multi-Source Observations |
| title_short | Dynamic Diagnosis of an Extreme Precipitation Event over the Southern Slope of Tianshan Mountains Using Multi-Source Observations |
| title_sort | dynamic diagnosis of an extreme precipitation event over the southern slope of tianshan mountains using multi source observations |
| topic | moisture transport diagnostic analysis black body temperature mesoscale convective system |
| url | https://www.mdpi.com/2072-4292/17/9/1521 |
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