Extreme rainfall sensitivity in convective‐scale ensemble modelling over Singapore
Extreme rainfall sensitivity in convective‐scale ensemble modelling over Singapore
复制标题
新加坡对流规模集合模拟中的极端降雨敏感性
DOI：
10.1002/qj.3601
复制
发表时间：
2019
影响因子：
8.9
通讯作者：
J. C. Lo
中科院分区：
文献类型：
--
作者：
A. Porson;S. Hagelin;D. F. Boyd;N. Roberts;R. North;S. Webster;J. C. Lo
开发了对流规模集合系统来预测新加坡周围强对流降雨的发生，重点是预测高影响事件。新的系统 SINGV-EPS 已嵌套在两个全球系统中：MOGREPS-G（英国气象局）和 EC-ENS (ECMWF)。预测新加坡等地区对流降雨的发生具有挑战性，本文讨论了使用允许对流集合来表征此类局地强降雨预测的不确定性。首先，对风、温度和降水进行为期一个月的验证，以评估每个集合的相对性能。这揭示了差异，但没有强有力的信号表明其中一个比另一个更好。结果不具有统计显着性，并且并非所有变量在一个集合或另一个集合中都始终更好。其次，从降水概率和集合成员间的变异性来分析SINGV-EPS的降水特征。 SINGV-EPS 对提供初始条件和边界的全局系综的选择很敏感。结果表明，在某些情况下，将两个整体结合起来是有好处的。第三，使用分散分数技能得分（dFSS）分析集合降水的扩散。我们比较了两种嵌套选项中初始扰动和横向边界条件扰动的影响。初始扰动在预测开始时占主导地位，影响长达 T+24 h，并且与不确定性的大规模增长相关。父系综和横向边界条件的影响在预测结束时占主导地位，并且往往对更大的尺度产生更大的影响。
A convective‐scale ensemble system was developed to predict the occurrence of heavy convective rainfall around Singapore with a focus on the prediction of high‐impact events. The new ensemble SINGV‐EPS has been nested within two global ensembles, MOGREPS‐G (UK Met Office) and EC‐ENS (ECMWF). Predicting the occurrence of convective rainfall in an area such as Singapore is challenging and this article discusses the use of the convection‐permitting ensemble to characterize the uncertainties in the prediction of such localized heavy rainfall. First, verification of wind, temperature, and precipitation is performed for a month‐long period to assess the relative performance of each ensemble. This reveals differences, but no robust signal to say one is better than the other. The results are not statistically significant and not all variables are consistently better with one ensemble or the other. Secondly, the precipitation characteristics of SINGV‐EPS are analysed from probabilities of precipitation and variability among the ensemble members. SINGV‐EPS is sensitive to the choice of the global ensemble providing the initial conditions and boundaries. The results suggest there is benefit, in some cases, from combining the two ensembles. Thirdly, the spread of the ensemble precipitation is analysed using the dispersion Fractions Skill Score (dFSS). We compare the impact of the initial perturbations and the perturbations in lateral boundary conditions in both nesting options. The initial perturbations dominate in the beginning of the forecasts, with influence up to T+24 h, and are associated with an upscale growth of the uncertainties. The impact of the parent ensemble and lateral boundary conditions dominate at the end of the forecast and tend to influence larger scales more.