Case study on the phenomena of gust front self-occlusion over the Yangtze River Delta region, China

This study first discovered and proposed the self-occlusion phenomenon of gust fronts over the Yangtze River Delta region, China. Two types of mechanisms, namely ‘Frictional Dynamic Deceleration Type’ and ‘Uneven Cold Pool Outflow Replenishment Type’, can cause the self-occlusion phenomenon of gust fronts. The formation mechanism of this phenomenon is attributed to the frictional resistance of local terrain and the uneven thermal distribution within the cold pool, which cause variations in the velocity of different parts of the gust front. Under such circumstances, the warm air ahead of the middle section of the gust front is forced to rise due to the converging compression of the frontal surfaces on both sides, thereby leading to the occurrence of atypical occluded front. On Doppler radar reflectivity images, both two types of self-occlusion gust front appears in the shape of the letter “ω.” This study will further deepen the theoretical understanding of the movement and evolution mechanism of gust fronts.