SWCWARMS模式不同起报时次对“18·05·21”强降水过程的预报能力评估

Prediction Ability Assessment on SWCWARMS Model Using Different Starting Times during Case“18·05·21”

针对2018年入汛以来四川地区首场区域性暴雨天气过程(“18·05·21”过程),利用西南区域中尺度业务模式(SWCWARMS)的预报结果,通过对比分析两个不同起报时次对此次强降水天气过程的预报结果,发现:随着预报时次的临近,其降雨的预报效果越好;在临近降水发生过程前以观测资料和再分析资料启动模式,对大气状态的刻画比用模式运行结果更为真实,一方面可以通过改善大气的温湿结构来改变层结状态,影响其稳定度,另一方面通过改善其环流场,增强低层的气旋性辐合和水汽的输送,从动力角度影响整个降水过程。采用更为真实的初始场启动模式以后,能更加准确地模拟出降水前后时段能量/水汽的积累和释放的热力过程,以及涡度、散度和垂直上升运动等动力因子共同协调发展过程,因此对预报效果有正反馈。

Base on the prediction results of southwest regional meso-scale business model for the first regional heavy rain weather process in Sichuan on 21 May 2018,to comparative analysis of forecast results by different starting tim es,found that the more near to get the forecast effect is better.The results show that:the description of the atmospheric state is more realistic when the observed data and reanalysis?data are used before the occurrence of precipitation.On the one hand,the stratification state can be changed by improving the temperature and humidity structure of the atmosphere to affect its stability;on the other hand,the cyclonic convergence and moisture transport in the lower layer can be enhanced by improving its circulation field,thus affecting the whole precipitation process from a dynamic perspective.The more realistic initial field starting model can more accurately simulate the thermodynamic process of energy/water vapor accumulation and release before and after precipitation,as well as the coordinated development process of dynamic factors such as vorticity,divergence and vertical rising m otion,so it has a positive impact on the prediction effect.