Atypical Occlusion Process Caused by the Merger of a Sea-breeze Front and Gust Front

• Published in: Advances in atmospheric sciences Vol. 32; no. 10; pp. 1431 - 1443
• Main Authors: Abulikemu, Abuduwaili, Xu, Xin, Wang, Yuan, Ding, Jinfeng, Wang, Yan
• Format: Journal Article
• Language: English
• Published: Heidelberg Science Press 01.10.2015; Springer Nature B.V; Key Laboratory of Mesoscale Severe Weather (Ministry of Education),School of Atmospheric Sciences, Nanjing University, Nanjing 210046%Tianjin Weather Modification Office,Tianjin,300074
• Subjects: Atmospheric models; Atmospheric Sciences; Cyclones; Earth and Environmental Science; Earth Sciences; Geophysics/Geodesy; Meteorology; Severe weather; Wind; 合并; 天气尺度; 对流天气; 对流风暴; 海风; 温带气旋; 闭塞; 阵风锋; China, People's Rep; gust front; sea-breeze front; occlusion process; merger
• ISSN: 0256-1530; 1861-9533
• DOI: 10.1007/s00376-015-4260-2

An atypical occlusion process that occurred in North China on 14 July 2011 is studied based on both observations and a real-data Weather Research and Forecasting （WRF） model simulation. The results show that this atypical occlusion process was significantly different from the traditional, synoptic-scale occlusion process that occurs within extratropical cyclones. It was caused by the merger of two cold-type mesoscale fronts. One of the fronts developed from the gust front of convective storms, while the other was a sea-breeze front. As the two fronts moved towards each other, the warm air between them was squeezed and separated from the surface. An atypical occluded front was formed when the two fronts merged, with the warm air forced aloft. This kind of occlusion is termed a ＂merger＂ process, different from the well-known ＂catch-up＂ and ＂wrap-up＂ processes. Moreover, local convection was found to be enhanced during the merger process, with severe convective weather produced in the merger area.