Convection Initiation Resulting From the Interaction Between a Quasi‐Stationary Dryline and Intersecting Gust Fronts: A Case Study. Issue 5 (1st March 2019)

• Record Type: Journal Article
• Authors: Bai, Lanqiang; Meng, Zhiyong; Huang, Yipeng; Zhang, Yunji; Niu, Shuzhen; Su, Tao
• Is Part Of: Journal of geophysical research. Volume 124:Issue 5(2019)
• Page Start: 2379
• Page End: 2396
• Publication Date: 2019-03-01
• Subjects: convection initiation -- dry line -- gust front -- squall line -- cold vortex -- China; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1029/2018JD029832
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: This study explores the convection initiation (CI) of a high‐impact squall line that occurred in central eastern China on 3 June 2009 based on observations and numerical modeling. The CI occurred in a scenario in which a set of intersecting gust fronts, organized in a distinct scalloped pattern, propagated toward an area of enhanced moisture produced by a near‐surface convergence line. This convergence line developed in a quasi‐stationary dryline zone. The dryline primed the preconvective environment by deepening the moist layer prior to the arrival of the intersecting gust fronts. The onset of CI occurred approximately 30 min after these intersecting gust fronts passed through the CI location, which was on the dry side of the dryline. Although these gust fronts acted as a strong signal for CI potential, CI did not occur along the entire length of the scalloped pattern of the intersecting gust fronts. The exact locations of the initiated convective cells were at the vertices of the scalloped pattern. An idealized simulation using a cloud model was conducted, demonstrating that the vertex regions were characterized by more favorable dynamical conditions for CI compared to the nonvertex regions along the scalloped outflow boundary. The greater CI probability over the vertex region was attributed to the greater magnitudes and larger vertical and horizontal extents of updrafts. Key Points: The initiation of a squall line occurred when a set of intersecting gust fronts approached a quasi‐stationary dryline Convection was initiated at the vertex regions along the scalloped pattern of the intersecting gust fronts Vertex regions of the intersecting gust fronts had greater magnitudes and larger vertical and horizontal extents of updrafts