2015/2016年超强厄尔尼诺事件背景下我国月预测技巧差异分析
投稿时间: 2016-10-07  最后修改时间: 2016-10-07  点此下载全文
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作者单位E-mail
陈丽娟 国家气候中心 chenlj@cma.gov.cn 
李想 国家气候中心  
李维京 国家气候中心  
李景鑫 中国气象科学研究院  
基金项目:The National Basic Research Program of China (973 Program)
中文摘要:利用中国站点观测降水资料、国家气候中心月动力延伸(DERF2.0)回报和预报数据、NCEP/NACR再分析数据、国家气候中心发布的月尺度降水预测评分,通过评估和诊断分析指出:在2015/2016年超强厄尔尼诺事件背景下,两年内的月降水发布预报能力有明显不同,而DERF2.0对环流的预测能力也表现出在2015年(厄尔尼诺发展位相)预报技较高且稳定,而2016年(厄尔尼诺衰减位相)预报技巧总体偏低。进一步分析2015年夏季和2016年夏季预测技巧高低的原因发现,亚洲-太平洋涛动(Asia-Pacific Oscillation, APO)可能起到重要影响。2015年为APO低指数年,而2016年为APO高指数年,同时具有高指数年的典型环流特征,即对流层高层南亚高压偏强,亚洲西风急流增强,南亚东风急流增强,北太平洋槽增强;低层亚洲低压和北太平洋副高增强。而DERF2.0也预测出部分APO高指数年的特征,包括东亚中纬度为弱偏南风距平,梅雨锋区偏北。分析显示APO高指数对应的环流特征与厄尔尼诺衰减位相对西北太平洋环流的影响不同。在厄尔尼诺和APO物理影响途径不一致时,直接影响到东亚环流可预报性的高低,也影响到动力模式的预报技巧。
中文关键词:厄尔尼诺事件  月预测技巧  可预报性  APO指数
 
The analysis of different monthly prediction skills over China in the 2015/2016 super El Nino events
Abstract:Based on the station data, BCC_DERF2.0 hindcast and forecast data, NCEP/NCAR reanalysis data and the score of NCC issued monthly precipitation data, some useful results can be get from verification methods and diagnostic analysis. In the super El Nino event from 2015 to 2016, the skills of issued monthly precipitation prediction is high/stable in 2015 (El Nino developing phase) and low/unstable in 2016 ( El Nino decaying phase). And the skills of key circulation predicted by DERf2.0 show the similar results as that of precipitation. Further analysis show that Asia-Pacific Oscillation (APO) index is low in 2015 summer and high in 2016 summer. With higher APO index conditions in the upper troposphere, the summer South Asian high and North Pacific trough are stronger, while the westerly jet stream over Asia and easterly jet stream over South Asia strengthen. The Asian low and North Pacific subtropical high are stronger in lower troposphere. DERF2.0 predicted part of the features of high APO index years including the anomalous southerlies prevail at the midlatitudes of East Asia, more northward Mei-yu front. The high APO index in 2016 summer may bring opposite impact on circulation over northwest Pacific which is different from that of El Nino decaying results. This work shows that the predictability of monthly East Asian circulation and the skill of DERF2.0 are decided by the APO and El Nino phase. When the APO index is high and El Nino is in decaying phase, the predictability is low.
keywords:El Nino event  skill of monthly prediction  predictability  APO index
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