山西秋季一次飑线过程的云图特征及维持机制
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摘要
利用Himawari-8卫星红外、水汽云图和FY-2E卫星可见光云图资料,以及多普勒天气雷达拼图和常规气象站、自动气象站、高空观测资料,对2017年9月21日发生在山西境内的一次飑线天气过程进行云图特征及维持机制分析。结果表明:(1)蒙古冷涡是本次飑线过程的大尺度天气影响系统,地面冷锋东移至不稳定潜势区触发了飑线云系的生成;高低空系统配置结构的转变及地面中尺度高压外流冷空气与环境风场形成的中尺度气旋和辐合线,是飑线发展和维持的机制;对流云团在地面冷锋与850 hPa切变线之间合并发展,地面中尺度高压与低压的发展促使气压梯度增大,导致飑线增强,是飑线过境时地面大风形成的原因。(2)初生阶段,飑线形成于云顶亮温低值区后侧梯度大值区、云顶纹理粗糙区、干湿边界偏湿区一侧,冷云盖略超前于飑线;发展阶段,飑线回波在云顶亮温低值区加强,并沿着亮温低值中心移动的方向移动;成熟阶段,飑线雷达回波与云顶亮温低值区重合。(3)弧状云线、上冲云顶和对流云带一侧的暗影是对流云团加强发展的前期征兆。
Based on the infrared and water vapor cloud images of Himawari-8 satellite, the visible cloud images of FY-2 E satellite, the composite reflectivity factor mosaic maps of Doppler radar, the observation data of conventional weather stations and automatic weather stations and radionsonde data, the cloud image characteristics and maintaining mechanism of the squall line process in Shanxi Province on 21 September 2017 were analyzed. The results are as follows:(1) The squall line weather process was caused by the large-scale Mongolia cold vortex weather system. The surface cold front moved eastward to the unstable potential area, which triggered the formation of the squall line system. The transformation of system configuration structure in high and low level of troposphere and the formation of mesoscale cyclone and convergence line from the outflow cold air of surface mesoscale high pressure and environmental wind field were the development and maintenance mechanisms of the squall line. The convective cloud clusters merged and developed between the surface cold front and 850 hPa shear line, and the development of surface mesoscale high and low pressure increased the pressure gradient, which led to the enhancement of the squall line, and further caused surface gale during the passage of the squall line.(2) At the initial stage, the squall line was formed in the large gradient area behind the low cloud-top brightness temperature region, the rough texture area of cloud-top, the wet side of the dry and wet boundary, and the position of cold cloud cover slightly moved in front of the squall line. At the development stage, the echo of the squall line strengthened in low cloud-top brightness temperature region, and it moved along the moving direction of the low value center of brightness temperature. At the mature stage, the radar echo of the squall line coincided with the low value region of cloud-top brightness temperature.(3) The arcus cloud line, the up rushing cloud-top and the shadows on one side of convective cloud belt were the early signs of the development and enhancement of convective cloud clusters.
Based on the infrared and water vapor cloud images of Himawari-8 satellite, the visible cloud images of FY-2 E satellite, the composite reflectivity factor mosaic maps of Doppler radar, the observation data of conventional weather stations and automatic weather stations and radionsonde data, the cloud image characteristics and maintaining mechanism of the squall line process in Shanxi Province on 21 September 2017 were analyzed. The results are as follows:(1) The squall line weather process was caused by the large-scale Mongolia cold vortex weather system. The surface cold front moved eastward to the unstable potential area, which triggered the formation of the squall line system. The transformation of system configuration structure in high and low level of troposphere and the formation of mesoscale cyclone and convergence line from the outflow cold air of surface mesoscale high pressure and environmental wind field were the development and maintenance mechanisms of the squall line. The convective cloud clusters merged and developed between the surface cold front and 850 hPa shear line, and the development of surface mesoscale high and low pressure increased the pressure gradient, which led to the enhancement of the squall line, and further caused surface gale during the passage of the squall line.(2) At the initial stage, the squall line was formed in the large gradient area behind the low cloud-top brightness temperature region, the rough texture area of cloud-top, the wet side of the dry and wet boundary, and the position of cold cloud cover slightly moved in front of the squall line. At the development stage, the echo of the squall line strengthened in low cloud-top brightness temperature region, and it moved along the moving direction of the low value center of brightness temperature. At the mature stage, the radar echo of the squall line coincided with the low value region of cloud-top brightness temperature.(3) The arcus cloud line, the up rushing cloud-top and the shadows on one side of convective cloud belt were the early signs of the development and enhancement of convective cloud clusters.
引文
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[10] 苗爱梅,董春卿,王洪霞,等.“0613”华北飑线过程的多普勒雷达回波特征[J].干旱气象,2017,35 (6):1015-1026.
[11] 易笑园,宫全胜,李培彦,等.华北飑线系统中地闪活动与雷达回波顶高的关系及预警指标[J].气象,2009,35(2):34-40.
[12] 刘香娥,郭学良.灾害性大风发生机理与飑线结构特征的个例分析模拟研究[J].大气科学,2012,36(6):1150-1164.
[13] 李娜,冉令坤,高守亭.华东地区一次飑线过程的数值模拟与诊断分析[J].大气科学,2013,37(3):595-608.
[14] 潘玉洁,赵坤,潘益农,等.用双多普勒雷达分析华南一次飑线系统的中尺度结构特征[J].气象学报,2012,70(4):736-751.
[15] 郭弘,林永辉,周淼,等.华南暖区暴雨中一次飑线的中尺度分析[J].暴雨灾害,2014,33(2):171-180.
[16] 吴紫煜,姚雯,李超,等.京津冀地区中α尺度飑线过程中大风特征分析及成因初探[J].气象与环境科学,2016,39(2):90-98.
[17] 张琪.三门峡地区一次飑线天气成因及特征分析[J].气象与环境科学,2015,38(4):76-83.
[18] 崔强,王春明,张云.干侵入对江淮流域一次强飑线过程的作用分析[J].沙漠与绿洲气象,2016,10(2):18-24.
[19] 李艳芳,程胜,吴彬.2012年4月2日华东灾害性飑线大风成因分析[J].气象与环境科学,2014,37(4):59-65.
[20] 曹倩,杨茜茜,叶丹,等.一次飑线过程的雷达观测和数值模拟分析[J].干旱气象,2016,34(2):305-316.
[21] 张婉莹,花家嘉,侯书勋,等.河北唐山一次飑线过程的中尺度天气分析[J].干旱气象,2014,32(4):636-641.
[2] 蔡则怡,李鸿洲,李焕安.华北飑线系统的结构与演变特征[J].大气科学,1988,12(2):191-199.
[3] ROTUNNO R,KLEMP J B,WEISMAN M L.A theory for strong,long-lived squall lines[J].Journal of the Atmospheric sciences,1988,45:463-485.
[4] WEISMAN M L,KLEMP J B,ROTUNNO R.Structure and evolution for numerically simulated squall lines[J].Journal of the Atmospheric sciences,1988,45:1990-2013.
[5] 王晓芳,胡伯威,李灿.湖北一次飑线过程的观测分析及数值模拟[J].高原气象,2010,29(2):471-485.
[6] 郑淋淋,孙建华.干、湿环境下中尺度对流系统发生的环流背景和地面特征分析[J].大气科学,2013,37(4):891-904.
[7] 袁招洪.不同分辨率和微物理方案对飑线阵风锋模拟的影响[J].气象学报,2015,73(4):648-666.
[8] 丁青兰,刘武,朱晓虎,等.一次飑线天气过程多普勒雷达产品分析及临近预报[J].气象科技,2008,36(2):160-163.
[9] 赵玲,李树岭,魏光辉,等.一次飑线风暴的环境条件和雷达回波特征分析[J].气象与环境科学,2013,36(4):29-35.
[10] 苗爱梅,董春卿,王洪霞,等.“0613”华北飑线过程的多普勒雷达回波特征[J].干旱气象,2017,35 (6):1015-1026.
[11] 易笑园,宫全胜,李培彦,等.华北飑线系统中地闪活动与雷达回波顶高的关系及预警指标[J].气象,2009,35(2):34-40.
[12] 刘香娥,郭学良.灾害性大风发生机理与飑线结构特征的个例分析模拟研究[J].大气科学,2012,36(6):1150-1164.
[13] 李娜,冉令坤,高守亭.华东地区一次飑线过程的数值模拟与诊断分析[J].大气科学,2013,37(3):595-608.
[14] 潘玉洁,赵坤,潘益农,等.用双多普勒雷达分析华南一次飑线系统的中尺度结构特征[J].气象学报,2012,70(4):736-751.
[15] 郭弘,林永辉,周淼,等.华南暖区暴雨中一次飑线的中尺度分析[J].暴雨灾害,2014,33(2):171-180.
[16] 吴紫煜,姚雯,李超,等.京津冀地区中α尺度飑线过程中大风特征分析及成因初探[J].气象与环境科学,2016,39(2):90-98.
[17] 张琪.三门峡地区一次飑线天气成因及特征分析[J].气象与环境科学,2015,38(4):76-83.
[18] 崔强,王春明,张云.干侵入对江淮流域一次强飑线过程的作用分析[J].沙漠与绿洲气象,2016,10(2):18-24.
[19] 李艳芳,程胜,吴彬.2012年4月2日华东灾害性飑线大风成因分析[J].气象与环境科学,2014,37(4):59-65.
[20] 曹倩,杨茜茜,叶丹,等.一次飑线过程的雷达观测和数值模拟分析[J].干旱气象,2016,34(2):305-316.
[21] 张婉莹,花家嘉,侯书勋,等.河北唐山一次飑线过程的中尺度天气分析[J].干旱气象,2014,32(4):636-641.