The performances of bulk microphysical schemes were evaluated through comparisons with observations, including a new volume scanning video disdrometer targeting one of a typical snowfall event in Hokkaido, Japan. For the evaluation, downscaling experiments using three bulk microphysical schemes were conducted: a two-moment bulk scheme, a one-moment bulk scheme, and an improved version of the one-moment bulk scheme coupled with an identical dynamical core. The two-moment scheme successfully simulated the measured relationship between particle size and terminal velocity distribution (PSVD). On the other hand, the one-moment scheme overestimated the graupel frequency, its terminal velocity, and underestimated the particle diameter. The improved version of the one-moment bulk scheme reduced the overestimation of the terminal velocity of hydrometeors, but still overestimated the graupel frequency. We improved the overestimation of terminal velocity and the frequency of graupel in the one-moment scheme by modifying the assumption of the velocity–diameter relationship and the intercept parameter of the size distribution of graupel based on the results of the new disdrometeor. The observation of the new disdrometer would give us hints to improve the microphysics schemes in snowfall cases.

通过与观察结果的比较来评估整体微物理方案的性能，其中包括针对日本北海道一场典型降雪事件的新型体积扫描视频测速仪。为了进行评估，我们进行了使用三种本体微物理方案的降尺度实验：两步本体方案，一步本体方案和单步本体方案的改进版本并结合了相同的动力核心。两步法成功地模拟了所测得的粒度与最终速度分布（PSVD）之间的关系。另一方面，单矩方案高估了graupel频率，其末端速度，而低估了粒径。一矩体积方案的改进版本减少了对水凝物终端速度的过高估计，但仍然高估了graupel频率。通过基于新的判别器的结果，修改速度-直径关系的假设和and的尺寸分布的截距参数，我们改进了单矩方案中对velocity的终极速度和频率的高估。对新的测速仪的观察将给我们一些提示，以改善降雪情况下的微物理方案。