Analysis Of A Terrain Related Severe Convection In Zhejiang Province

Severe Convection (SC) is one of the important topics in weather research. The SC occurs more frequent and the trigger mechanism is more complex in Zhejiang Province as for its geographic condition, atmospheric circulation and topography complexity. This thesis analyzes SCs during2010to2012, summarizes their distribution characteristics and discovers the relation between distribution of SC and topography features based on the statistic results.Taking the case on2012.06.08as an example, the analysis is based on various observation data and which covers the environmental field features, heat produced by SC, vapor and power condition and the feature of hydrometer processes. The hydrometer consists of two different stages, which is invoked in west and southeast area separately. Also, the analysis on mesoscale activation reveals differences between west area and east area in Zhejiang:There exists a dew-point front, where both dry and wet water are fed continuously, that keeps and reinforces the front zone. Also, the strong convergence zone behind the rain, where low level air flow increases surface convergence, triggers the instable power in activation front zone to release. New convective cells constantly generate behind the system, strengthen and maintain the precipitation; The SC in southeast coastal area happens four hours later after the hydrometer in west. The existing sea breeze front in coastal area is reinforced with the temperature arise in local area. The original hydrometer zone approaches coastal area and leads to a cold flow; another dry hot stream from the southwest mountain rises at the same time. With the three air flows chaining up in the fixed location, the gradient increases rapidly. These three airflow show different natures, lift drastically along mountain chain after collision and activates SC.Besides, this thesis investigates the impact of the undulating topography to the SC process viaingredients-based methodology. The result on hydrometer in different latitude shows the prediction is more accurate with the gradient, which confirms the impact of topography to hydrometer.The numerical simulation of topography and latent heat reveals that the thermodynamics condition is not sufficient for severe convective weather in Southeast seashore in Zhejiang without the retroaction of latent heat. The existence of Tonggong mountain increases the instability of atmosphere and the lifting of air flow.