A Case Study on Convection Initiation Associated with Horizontal Convective Rolls over Ili River Valley in Xinjiang, Northwest China
The mechanism of convection initiation (CI) over Ili River Valley (IRV) in Xinjiang, Northwest China, was investigated based on both weather stations and radar observations and Weather Research and Forecasting (WRF) model simulation. Observations showed that many CIs occurred repeatedly, and most of...
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MDPI AG
2022-03-01
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| author | Meini Kong Abuduwaili Abulikemu Jingjing Zheng Mangsuer Aireti Dawei An |
| author_facet | Meini Kong Abuduwaili Abulikemu Jingjing Zheng Mangsuer Aireti Dawei An |
| author_sort | Meini Kong |
| collection | DOAJ |
| description | The mechanism of convection initiation (CI) over Ili River Valley (IRV) in Xinjiang, Northwest China, was investigated based on both weather stations and radar observations and Weather Research and Forecasting (WRF) model simulation. Observations showed that many CIs occurred repeatedly, and most of them underwent significant intensification both in size and intensity, and eventually formed an extreme rainfall-producing mesoscale convective system (MCS) in the IRV. Besides, there was a relatively strong boundary layer westerly jet (BLWJJ, horizontal wind speed exceeding 12 m s<sup>−1</sup>) along with significant cold advection. The overall features of the CIs and associated MCS are generally well reproduced by the WRF simulation. Simulation results showed that there were some horizontal convective rolls (HCRs) developed ahead of the BLWJ and generated significant convergence (up to ~2 × 10<sup>−</sup><sup>3</sup> s<sup>−</sup><sup>1</sup>) in the low level that further induced intense updraft aloft (vertical velocity exceeding 3.5 m s<sup>−1</sup>) which finally resulted in the CIs. Further investigations indicated that, as the main contributor to the HCRs, the BLWJ was generated due to the funneling effect when the descending westerlies entered the middle reaches of the IRV. A qualitative analysis based on the quasi-geostrophic omega equation revealed that the descending flow in mid- to lower troposphere in the middle reaches of the IRV was mainly contributed by the vorticity advection, while the descending in the lower troposphere was dominated by both vorticity advection and cold advection. |
| first_indexed | 2024-03-09T11:21:34Z |
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| issn | 2073-4441 |
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| last_indexed | 2024-03-09T11:21:34Z |
| publishDate | 2022-03-01 |
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| series | Water |
| spelling | doaj.art-c329ca34561749be9000257da0f7a2952023-12-01T00:18:40ZengMDPI AGWater2073-44412022-03-01147101710.3390/w14071017A Case Study on Convection Initiation Associated with Horizontal Convective Rolls over Ili River Valley in Xinjiang, Northwest ChinaMeini Kong0Abuduwaili Abulikemu1Jingjing Zheng2Mangsuer Aireti3Dawei An4Xinjiang Key Laboratory of Oasis Ecology, College of Geographical Science, Xinjiang University, Urumqi 830017, ChinaXinjiang Key Laboratory of Oasis Ecology, College of Geographical Science, Xinjiang University, Urumqi 830017, ChinaXinjiang Key Laboratory of Oasis Ecology, College of Geographical Science, Xinjiang University, Urumqi 830017, ChinaXinjiang Meteorological Observatory, Urumqi 830002, ChinaXinjiang Meteorological Observatory, Urumqi 830002, ChinaThe mechanism of convection initiation (CI) over Ili River Valley (IRV) in Xinjiang, Northwest China, was investigated based on both weather stations and radar observations and Weather Research and Forecasting (WRF) model simulation. Observations showed that many CIs occurred repeatedly, and most of them underwent significant intensification both in size and intensity, and eventually formed an extreme rainfall-producing mesoscale convective system (MCS) in the IRV. Besides, there was a relatively strong boundary layer westerly jet (BLWJJ, horizontal wind speed exceeding 12 m s<sup>−1</sup>) along with significant cold advection. The overall features of the CIs and associated MCS are generally well reproduced by the WRF simulation. Simulation results showed that there were some horizontal convective rolls (HCRs) developed ahead of the BLWJ and generated significant convergence (up to ~2 × 10<sup>−</sup><sup>3</sup> s<sup>−</sup><sup>1</sup>) in the low level that further induced intense updraft aloft (vertical velocity exceeding 3.5 m s<sup>−1</sup>) which finally resulted in the CIs. Further investigations indicated that, as the main contributor to the HCRs, the BLWJ was generated due to the funneling effect when the descending westerlies entered the middle reaches of the IRV. A qualitative analysis based on the quasi-geostrophic omega equation revealed that the descending flow in mid- to lower troposphere in the middle reaches of the IRV was mainly contributed by the vorticity advection, while the descending in the lower troposphere was dominated by both vorticity advection and cold advection.https://www.mdpi.com/2073-4441/14/7/1017convection initiationhorizontal convergence rollboundary level jetquasi-geostrophic omega equationXinjiangIli River Valley |
| spellingShingle | Meini Kong Abuduwaili Abulikemu Jingjing Zheng Mangsuer Aireti Dawei An A Case Study on Convection Initiation Associated with Horizontal Convective Rolls over Ili River Valley in Xinjiang, Northwest China Water convection initiation horizontal convergence roll boundary level jet quasi-geostrophic omega equation Xinjiang Ili River Valley |
| title | A Case Study on Convection Initiation Associated with Horizontal Convective Rolls over Ili River Valley in Xinjiang, Northwest China |
| title_full | A Case Study on Convection Initiation Associated with Horizontal Convective Rolls over Ili River Valley in Xinjiang, Northwest China |
| title_fullStr | A Case Study on Convection Initiation Associated with Horizontal Convective Rolls over Ili River Valley in Xinjiang, Northwest China |
| title_full_unstemmed | A Case Study on Convection Initiation Associated with Horizontal Convective Rolls over Ili River Valley in Xinjiang, Northwest China |
| title_short | A Case Study on Convection Initiation Associated with Horizontal Convective Rolls over Ili River Valley in Xinjiang, Northwest China |
| title_sort | case study on convection initiation associated with horizontal convective rolls over ili river valley in xinjiang northwest china |
| topic | convection initiation horizontal convergence roll boundary level jet quasi-geostrophic omega equation Xinjiang Ili River Valley |
| url | https://www.mdpi.com/2073-4441/14/7/1017 |
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