为探究土壤湿度非均匀性对青藏高原中尺度对流系统初生过程的影响，本文利用卫星遥感资料、地闪观测资料和再分析资料筛选出2022年8月10日青藏高原上空的一次由孤立对流初生发展而来的中尺度对流系统个例进行观测分析和数值模拟研究。结果表明：（1）本次中尺度对流系统在弱天气强迫背景下初生于06:00（世界时），发展过程中向东北方向移动并通过合并云团不断增强，在强对流阶段伴随有闪电活动。对流初生位置附近土壤湿度存在显著的西南干、东北湿的空间非均匀分布型。（2）基于中尺度数值模式，模拟了西南侧干区受地表热力强迫作用下形成的地面辐合，及由此产生的上升气流沿土壤湿度梯度方向发展、增强至形成对流初生的时空特征。对流初生发生时刻，初生位置上空低层大气处于干绝热层结状态下，对流有效位能（对流抑制能量）为 946. 5 J·kg-（1 0 J·kg-1），2 m 气温在对流初生发生前1 h达到对流温度，此时边界层高度突破自由对流高度，随后对流迅速发展并增强。（3）敏感性试验结果表明，去除土壤湿度非均匀特征后，初生对流强度减弱，位置向西移动，这与土壤湿度非均匀性改变对流初生前大气动热力和水汽条件有关，即土壤湿度非均匀性通过增强地表温度梯度从而间接增强西南侧干区感热通量，进而增强初生前地表上升运动，以及改变风场方向从而增强初生时刻该位置的地表风场和水汽的辐合强度，使得对流发展强度增大。（4）土壤湿度均一状态下，土壤湿度值的增加使地表水汽更充沛、地面风场辐合更强，进而使得水汽辐合强度增加，对流发展增强，同时较高的土壤湿度通过减小地表温度和感热通量抑制了对流初生发生前上升气流的发展强度，使对流发展过程减缓，导致对流初生的出现时间更晚。

In order to investigate the influence of soil moisture heterogeneity on the convective initiation stage of a mesoscale convective system over the Tibetan Plateau，an typical case of mesoscale convective system，developed from an isolated convective initiation process over the Tibetan Plateau on 10 August 2022，is studied by observational analysis and numerical experiments using satellite remote sensing data，cloud-to-ground lightning observations and reanalysis data. The results are as follows：（1）Under weak synoptic-scale forcing，the convective initiation stage of the mesoscale convective system occurred at 06:00（UTC，the same as after）. The convective cloud then moved northeastward and intensified through merging clouds，accompanied by lightning activity during the development of the mesoscale convective system.（2）Based on the mesoscale numerical model WRF， we simulated the surface convergence in the southwestern dry zone formed by surface thermal forcing，as well as the development and intensification process of the updrafts caused by the surface convergence until the formation of the convective initiation with a moving direction along the soil moisture gradient. At convective initiation time，the low-level atmosphere over the convective initiation location was in a dry adiabatic state with a CAPE （CIN）of 946. 5 J·kg-1（0 J·kg-1）. 2 m air temperature reached the convective temperature 1h before the occurrence of convective initiation，when the height of the planetary boundary layer was higher than the level of free convection. The convection then strengthened rapidly.（3）The results of the sensitivity experiments show that the removal of the soil moisture inhomogeneity weakened the intensity of the convection and shifted the position of the convective initiation westward，which is related to the fact that the soil moisture inhomogeneity changed the atmospheric dynamical，thermal and moisture conditions before the occurrence of the convective initiation. The soil moisture inhomogeneity indirectly increased the sensible heat flux of the dry zone located to the southwest of the convective initiation location by increasing the surface temperature，thus increasing the upward motion at surface before the occurrence of the convective initiation. Meanwhile，the direction of the wind field near the convective initiation location was also changed and thus increasing the convergence of the surface wind field and water vapor at the convective initiation time，which led to an increase in the intensity of the convection.（4）Under the condition of homogeneous soil moisture distribution，increasing soil moisture led to more abundant surface water vapour and stronger convergence of the surface wind field，which in turn led to an increase in the intensity of water vapour convergence and enhanced the development of convection. In addition，higher soil moisture inhibited the intensity of pre-convective initiation updraft development by decreasing surface temperature and sensible heat fluxes，which slowed the development of convection and led to a later convective initiation time.