Implications from Subseasonal Prediction Skills of the Prolonged Heavy Snow Event over Southern China in Early 2008
Implications from Subseasonal Prediction Skills of the Prolonged Heavy Snow Event over Southern China in Early 2008
复制标题
2008年初华南持续大雪事件的次季节预报技术的启示
DOI：
10.1007/s00376-021-0402-x
复制
发表时间：
2021
影响因子：
5.8
通讯作者：
Li Tim
中科院分区：
文献类型：
--
作者：
Zhang Keyue;Li Juan;Zhu Zhiwei;Li Tim
2008年1月10日至2月3日，我国南方地区发生了持续时间异常长的强降雪天气，造成了重大的经济损失和人员伤亡。任何动力学模型能在多大程度上预测这样的极端事件对于防灾减灾至关重要。结果表明，ECMWF、CMA 1.0和CMA 2.0三个S2 S模式分别能较好地预报10 d和10-15 d的降水和地表温度的分布和强度。这一成功归功于模式能够预测热带和中纬度地区两个重要低频系统的演变[持续的西伯利亚高压和马登-朱利安振荡（MJO）的抑制阶段]，特别是在ECMWF模式中。然而，超过15天的领先优势后，这三个模型几乎没有表现出预测本次PHSE的能力。捕捉两个关键循环系统的偏差是导致预测2008年PHSE超过15天领先优势的能力较低的原因。一方面，模式不能再现西伯利亚高压的持续性，从而低估了华南地区SAT的负距平。另一方面，模式不能准确地捕捉到MJO对对流的抑制，导致异常偏南风和水汽输送减弱，从而低估了华南地区的降水。奇异值分解（SVD）分析表明，临界环流系统与华南地区SAT/降水之间存在较强的历史关系，指示常规事件和极端事件的可预测性源的保真度（例如，（2008年）。
An exceptionally prolonged heavy snow event (PHSE) occurred in southern China from 10 January to 3 February 2008, which caused considerable economic losses and many casualties. To what extent any dynamical model can predict such an extreme event is crucial for disaster prevention and mitigation. Here, we found the three S2S models (ECMWF, CMA1.0 and CMA2.0) can predict the distribution and intensity of precipitation and surface air temperature (SAT) associated with the PHSE at 10-day lead and 10-15-day lead, respectively. The success is attributed to the models’ capability in forecasting the evolution of two important low-frequency systems in the tropics and mid-latitudes [the persistent Siberian High and the suppressed phase of the Madden-Julian Oscillation (MJO)], especially in the ECMWF model. However, beyond the 15-day lead, the three models show almost no skill in forecasting this PHSE.The bias in capturing the two critical circulation systems is responsible for the low skill in forecasting the 2008 PHSE beyond the 15-day lead. On one hand, the models cannot reproduce the persistence of the Siberian High, which results in the underestimation of negative SAT anomalies over southern China. On the other hand, the models cannot accurately capture the suppressed convection of the MJO, leading to weak anomalous southerly and moisture transport, and therefore the underestimation of precipitation over southern China.The Singular Value Decomposition (SVD) analyses between the critical circulation systems and SAT/precipitation over southern China shows a robust historical relation, indicating the fidelity of the predictability sources for both regular events and extreme events (e.g., the 2008 PHSE).