This paper discusses the effect of graupel/hail parameters on a convective system in Yangjiang, Guangdong Province. The simulation results using the original model settings were similar to observations in terms of radar reflectivity and sea level pressure, as well as the identification of hydrometeor particle phase by X-band dual-polarization radar data. Sensitivity tests using changed parameters of graupel/hail indicated that a size distribution with larger and denser but fewer hail hydrometers resulted in a weaker development of the convective system in the horizontal and vertical directions. With a large terminal velocity of hail, the melting rate of graupel and evaporation rate of rain were the lowest. Hail could reach the ground and the mixing ratio of rain was the largest near the ground. Precipitation, including rainwater and hail, was the largest. However, a size distribution with smaller and lighter but numerous graupel hydrometers resulted in a stronger development of the convective system. The melting rate of graupel and evaporation rate of rain were the largest. More graupel particles were stranded in the air for a longer time—and the maximum mixing ratio of rain was the largest. The precipitation amount, including rainwater only, was the smallest. The changes to graupel parameters also led to differences in microphysical processes.
本文利用WRF中尺度数值模式探讨了霰/雹粒子参数对广东省阳江市一次对流系统的模拟影响。使用原模式设置得到的模拟结果与雷达回波分布、海平面气压等观测结果很一致,并且,模拟的粒子分布与X波段双偏振雷达资料反演的水成物粒子相态识别结果很吻合。改变霰/雹粒子参数的敏感性试验模拟结果表明，当霰/雹粒子的尺度大、质量密度大,而数浓度小时，对流系统无论在水平方向还是在垂直方向均发展较弱。这是由于霰/冰雹的下落末速度变大时，导致霰/冰雹粒子融化和雨水蒸发最少，冰雹可降落到地面，并且在地面附近雨水混合比最大。因此，地面降水（包括雨水和冰雹）最大。然而，当霰/雹粒子粒子的尺度小、质量密度小而数浓度大时，对流系统发展较强。这是由于霰/冰雹的下落末速度变小时，导致霰/冰雹粒子融化和雨水蒸发最多，有更多的霰粒子较长时间滞留在空中，雨水混合比最大值到达最大。因而，地面降水（仅包含雨水）最小。霰粒子参数的改变还导致云微物理过程的差异。