Effects of the Underlying Surface on the Intensity of Linear Storms in the Bohai Strait
MEI Chanjuan
HOU Shumei
TANG Huan
WAN Fujing
ZHAO Haijun
Abstract：Using observational data,radar data,and ERA5 reanalysis data,this study analyzed the impact of the underlying surface on the intensity of linear storms in the Bohai Strait through the analysis of two severe convective events with distinct evolutionary characteristics in 2021.The results show that both storm strengthening and weakening occurred under weak synoptic forcing,with low-level warm temperature ridge supporting potential instability stratification.Nocturnal thermal circulation and dynamic forcing dominated storm modulation through surface thermal heterogeneity,while daytime sea surface temperature(SST)gradients played secondary roles.Eastward-moving nocturnal linear storms typically weakened over the Bohai Strait cold-water region due to divergent flows.Storm enhancement occurred when ascent in the near-surface layer(induced by surface thermal contrasts)vertically aligned with environmental convergence.In this case,a relatively shallow mesoscale secondary circulation developed near the Bohai Strait,characterized by ascending motion in warm water areas and descending motion in cold water regions within the near-surface layer.Environmental convergence was often caused by outflows of other surrounding storms lifted by environmental wind convergence.Additionally,environmental easterly airflow and strong vertical wind shear at 0-1 km were conducive to maintaining the ascending motion of linear storm movement;sea breeze and coastline curvature also affected coastal convection.
Keywords：sea-land breezesea surface temperaturecold airmesoscale secondary circulationvertical wind shear
Publication Date：2025-02-28
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：13( 112-124 )