中文摘要：

采用2006—2011年的降水、探空和陆面资料,分析了对流降水时的边界层和陆面过程特征,发现在对流降水前3 d至后1 d的最大混合层厚度逐日变化中,在降水之前基本呈现出逐渐增厚并在降水前日达到最大,说明边界层热力对流环境很可能是对流性天气发展的重要能量基础。基于此,又重点分析了陆面通量的角色和作用,发现对流降水发生时段不同,陆面热通量也存在明显差异,傍晚对流降水的感热通量累积值是最大的,而午后对流降水的潜热通量最小;按降水量分类对比,感热通量与降水量存在较明显的正相关关系,而潜热通量则与降水量的关系复杂;当前1 d最大混合层厚度超过3 000 m或当日的感热通量累计值超过2 000 W·m^-2时,则在当日发生降水量超过17 mm的对流性降水的概率较大。综合分析表明,陆面热力作用对对流天气形成,尤其是对傍晚时段的对流降水具有重要作用,而局地蒸发对局地水循环的形成还不足以对对流降水产生实质性的贡献。

英文摘要：

Land surface process and atmospheric boundary layer play an important role in energy and water vapor exchange and transmit for earth-atmosphere system,and they also have an inherent connection with severe weather disaster. The characters of boundary layer and the land surface process related to severe convection weather were analyzed using the precipitation data,sounding data and land surface data during 3 periods from 2006 to 2010. It was found that the maximum atmospheric mixed layer depth（ hereafter referred to as ML depth） was in a continuous and gradual thickening before a convection weather,and reached a maximum at last on the day before rainfall. All of these demonstrated that the thermal convection environment of boundary layer maybe was an important energy source for the convection weather development. Based on this idea,the role and character of land surface process was studied. An obvious difference was also found through the statistical land surface heat fluxes by dividing the process into 3 periods according to the occurrence time of convective precipitation,the cumulative value of sensible heat flux was maximum in nightfall convection period,and the latent heat flux was minimum in afternoon convection period. There was a significant positive correlation between sensible heat flux and precipitation,but a complex correlation between latent heat flux and precipitation. When the ML depth was thicker than 3 000 m on previous day or the accumulate sensible heat flux reached 2 000 W·m^- 2,the probability of occurring convective precipitation higher than 17 mm on than day was high. The results demonstrated that there was an important function of land-surface thermal effect on the formation of convection weather,however,the local evaporation was not enough to result in a substantial contribution to the convection precipitation formation in local water cycle.