王亦平,陆维松,潘益农,王元. 2008. 淮河流域东北部一次异常特大暴雨的数值模拟研究 Ⅱ: 不稳定条件及其增强和维持机制分析[J]. 气象学报, 66(2):177-189, doi:10.11676/qxxb2008.018
淮河流域东北部一次异常特大暴雨的数值模拟研究 Ⅱ: 不稳定条件及其增强和维持机制分析
Numerical simulation of a torrential rain in the northeast of huaihe basin partⅡ: instability conditions and the mechanism of intensification and maintenance
投稿时间:2006-11-16  修订日期:2007-04-24
DOI:10.11676/qxxb2008.018
中文关键词:  中尺度深湿对流系统,不稳定,CVV ,增强维持机制
英文关键词:Deep moist MCS, Instability, Convective vorticity vector, Intensification and maintenance mechanism
基金项目:国家教育部“高等学校博士学科点专项科研基金”项目(20040300002)
作者单位
王亦平 南京信息工程大学江苏省气象灾害重点实验室南京210044
南京大学大气科学系,南京210093 
陆维松 南京信息工程大学江苏省气象灾害重点实验室南京210044 
潘益农 南京大学大气科学系中尺度灾害性天气教育部重点实验室,南京210093 
王元 南京大学大气科学系中尺度灾害性天气教育部重点实验室,南京210093 
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中文摘要:
      利用“淮河流域东北部一次异常特大暴雨的数值模拟研究Ⅰ”的数值模拟结果,分析了几种不稳定、CVV 与中尺度深湿对流系统之间的关系,并分析了不稳定条件的增强和维持机制,结果表明:(1)中低层对流不稳定是深湿对流系统发生的先决条件,由于低层存在辐合,使得周围湿空气向暴雨区集中,对流单体在暴雨区汇聚,且发生合并增强,台风左前方向暴雨区输送对流不稳定能量等,是使得暴雨区对流不稳定重新建立和加强的重要机制。(2)深湿对流系统的中低层不仅有对流不稳定,而且还有斜压不稳定、条件对称不稳定,而中高层必须有湿斜压不稳定和条件对称不稳定。深湿对流系统中高层西(北)侧为负MPV2 柱,东(南)侧为正MPV2 柱;(3)深湿对流系统中惯性不稳定柱与惯性稳定柱相间分布,西(南)侧为负CVV 柱,东(北)侧为正CVV 柱,负CVV 柱对深湿对流起激发作用;(4)惯性不稳定、湿倾斜不稳定和条件不稳定产生强的倾斜式对流,而强的倾斜式上升运动加强了深对流系统北侧高层的南风分量,因深对流系统南侧低层出现补偿性下沉气流,因而低层南风加强,高低空急流中心的加强会进一步加强对流的发展,使得惯性不稳定、湿倾斜不稳定和条件不稳定增强和维持,这是一个正反馈过程。(5)在暴雨中心以东维持一顺切变环流,同时暴雨中心的浅对流单体吸收来自南方的水汽和不稳定能量,中尺度辐合线和β 中尺度涡旋对对流单体起组织和增强作用,对流系统中辐合、辐散柱相间分布,强散度柱与强涡柱互伴互耦,都有利于形成中尺度深湿对流系统,使不稳定向纵深方向发展,从而使得不稳定得到增强和维持。
英文摘要:
      By using of the result of the simulation in part Ⅰ of this study, as well as the mechanism of intensification and maintenance, the relationship between deep moist mesoscale convective system (DMMCS) and instability, convective vorticity vector(CVV) are analyzed. Results show that (1) middle-low level convective instability is the precondition of the occurrence of DMMCS. The surrounding moisture centralize in the heavy rain area because of the low-level convergence. The convergence and merging enhancement of convection cells, and the convective instability energy transporting from the left-front of typhoon are the important mechanism of the rebulid of convective instability. (2) Not only baroclinic instability and conditional symmetry instability lie in the middle-low level, but also lie in the middle-upper level of DMMCS. At the west (east, south, north) of DMMCS, there lies negative (positive, positive, negative) MPV2 column. (3) In DMMCS, there is an alternative distribution of inertial instability column and inertial stability column, at the west and south (east and north), there lie negative (positive) CVV columns, while negative CVV column is beneficial to deep moist convection. (4) The strong slantwise convection induced by inertial instability, baroclinic instability and conditional symmetry instability will enhance the upper level southerly component. Because of the appearance of the compensated downdraft at the low level of the south side of DMMCS, the low level southerly is intensified, the enhancement of upper- and low-level cores are in favor of the development of DMMCS. And that will do favor for the reinforcement and maintenance of inertial instability, baroclinic instability and conditional symmetry instability, it is a positive feedback process. (5) There lies a downshear circulation to the east of rainfall cell, shallow convections near this cell absorb the vapor and instability energy coming from the south, and meso-scale convergence line and meso-β-scale vortex organize and intensify convective cells. In DMMCS, there are an alternative distribution of convergence and divergence columns, and the couple between strong divergence and vorticity columns. They are both in favor of the development of DMMCS, and the instability will be intensified and maintained for its developing in depth.
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