针对2016年7月26日发生在江苏北部的一次弱天气尺度强迫下强对流过程, 选用WRF（Weather Research and Forecasting）模式中具有一定代表性的5种云微物理参数化方案进行模拟。结果表明, 只有NSSL 1-momlfo方案能够较好地再现回波的位置、 强度及层云区, 其余四种方案模拟的回波与实况存在不同程度的差异。原因是不同方案模拟的热动力结构、 水成物及相变潜热的空间分布存在差异, 其中NSSL方案模拟的上升气流更强劲, 冷池范围也更集中; 水成物集中在一个狭窄的水平区域, 雨水在中低层较多, 雪粒子和霰粒子在中高层较多; 与此相应, NSSL方案相变潜热释放最多, 进一步加强了上升运动。
Five typical cloud microphysics parameterization schemes, i.e.NSSL 1-momlfo scheme, Morrison 2-moment scheme, Thompson scheme, WDM6(WRF Double-Moment 6-class) and HUJI spectral bin microphysics (FAST), in the WRF (Weather Research and Forecasting) model were used to simulate a severe convective process under weak synoptic-scale forcing in the north of Jiangsu Province on July 26, 2016.The results show that only the NSSL 1-momlfo scheme can reproduce this severe convective process well, including the location, the intensity of the strong convective echo region and the stratiform cloud region, while the simulated radar echoes with Morrison, Thompson, WDM6 and HUJI schemes significantly differ from the real observations.The reason for the differences is investigated by comparing the effects of different schemes on the dynamic and thermodynamic structure of strong convection and the spatial distribution of hydrometeors and latent heat.It is found that the NSSL scheme shows the strongest updraft, although low-level wind convergence is simulated with the NSSL, WDM6 and HUJI schemes.Meanwhile, more concentrated cold pool is found out with the NSSL scheme, while the cold pool distributes over a large area in both the WMD6 and HUJI scheme, which is consistent with wider and stronger simulated radar echo.Conversely, the cold pool is distributed in a narrow region in the Morrison scheme and Thompson scheme, especially in the Morrison scheme, where almost no cold pool is found out.Furthermore, the distribution of hydrometeors with the NSSL scheme is concentrated in a horizontal narrow area, with more rainwater in the middle and lower layers and more snow particles and graupel particles in the middle and upper layers.The distribution of hydrometeors in the rest four schemes is quite different from that in the NSSL scheme: almost no rain, cloud droplets and ice in the Morrison scheme; except for snow distributed in a larger area, no ice and graupel, and almost no rain and cloud droplets in the Thompson scheme; the wide distribution of rain, snow and graupel with several large value centers but almost no cloud ice in the WDM6 scheme; a wide distributed snow and ice in HUJI scheme.Meanwhile, the NSSL scheme produces the most latent heat, resulting in a strengthened updraft, while the latent heat in the other four schemes is less than the NSSL scheme in both intensity and spatial distribution.And furthermore, it is the least in the Morrison scheme.
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