气象领域极端事件的长程相关性

利用固定阈值法研究了Lorenz系统极端事件序列的长程相关性特征.研究结果表明：不同阈值标定的极端事件序列具有长程相关性,且标度指数α比较接近,但都比Lorenz系统略小.不同的初值对极端事件序列的长程相关性影响不大,即对初值不敏感性,但Lorenz系统的长程相关性随着控制参数的增大而明显减弱.通过与高斯白噪声序列对比研究发现,Lorenz系统极端事件序列具有较好的记忆性特征.最后采用国家气候中心194个测站1957年—2004年日最高气温观测资料进行分析,揭示了实际气象要素中存在类似的规律. 关键词： Lorenz系统 极端事件 长程相关性 记忆性     

The characteristics of clusters of weather and extreme climate events in China during the past 50 years

The pick-up algorithm by the k-th order cluster for the closest distance is used in the fields of weather and climactic events, and the technical terms clustered index and high clustered region are defined to investigate their temporal and spatial distribution characteristics in China during the past 50 years. The results show that the contribution of extreme high-temperature event clusters changed in the period from the 1960s to the 1970s, and its strength was enhanced. On the other hand, the decreasing trend in the clusters of low-temperature extremes can be taken as a signal for warmer winters to follow in the decadal time scale. Torrential rain and heavy rainfall clusters have both been lessened in the past 50 years, and have different cluster characteristics because of their definitions. Regions with high clustered indexes are concentrated in southern China. The spatial evolution of the heavy rainfall clusters reveals that clustered heavy rainfall has played an important role in the rain-belt pattern over China during the last 50 years.