| 华北汛期降水量变化中年代际和年际尺度的分离 |
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| 引用本文： | 陆日宇.华北汛期降水量变化中年代际和年际尺度的分离[J].大气科学,2002,26(5):611-624. |
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| 作者姓名： | 陆日宇 |
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| 作者单位： | 中国科学院大气物理研究所,北京,100080 |
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| 基金项目： | 中国科学院资源环境领域知识创新工程重要方向项目KZCX2-203资助 |
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| 摘 要： | 华北地区汛期(7月和8月)降水量的变化中,不仅具有年际变化的特征,同时还具有明显的年代际变化特征.我们将这两种时间尺度进行分离,即将降水量的变化进行5年滑动平均,以滑动平均值代表年代际变化,并以每年的汛期降水量与滑动平均值的差代表去除了年代际变化后的年际变化.然后,利用NCAR/NCEP再分析资料对与这两种不同时间尺度相关联的大气环流异常进行了分析,发现两者具有不同的表现,说明影响这两种不同时间尺度的物理原因可能是不同的.与年代际变化相对应的大气环流异常主要表现为出现在我国东部地区的南北风异常以及欧亚大陆上空的位势高度异常.若对这两种时间尺度不进行分离,而直接按讨论年际变化的一般方法简单地分析与年际变化相关联的大气环流异常时,所得到的分析结果中既包含与华北降水年代际变化相关联的大气环流异常,又包含与去除年代际变化后的年际变化相关联的大气环流异常.而除去年代际变化后,与华北汛期降水年际变化相关联的大气环流异常主要表现为在东亚上空位势高度和纬向风的异常,意味着急流在涝年位置偏北.
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| 关 键 词： | 华北 降水量 年代际变化 年际变化 大气环流异常 |
| 修稿时间： | 1/1/2002 12:00:00 AM |
Separation of Interannual and Interdecadal Variations of Rainfall in North China |
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| Lu Riyu.Separation of Interannual and Interdecadal Variations of Rainfall in North China[J].Chinese Journal of Atmospheric Sciences,2002,26(5):611-624. |
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| Authors: | Lu Riyu |
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| Abstract: | The precipitations in North China in rainy seasons (July and August, or JA) show variation characteristics both on interannual and interdecadal scales. In this study, these two time scales are separated by: considering five-year running mean of JA precipitations as interdecadal variations, and considering the difference between JA precipitations and the interdecadal variations as interannual variations. After the separation, analyses are performed by use of NCAR/NCEP reanalysis data on respective atmospheric circulation anomalies associated with these two time scales. The great differences between these two kinds of asociations suggest the different physical mechanisms for interannual and interdecadal variations of JA rainfall in North China. The atmospheric circulation associations on interdecadal scale include the remarkable anomalies of the meridional velocity over the eastern part of China and geopotential heights over the Asian continent. The associations on the interannual scale by a routine composite method without the separation exhibit the mixed characteristics of two types of atmospheric circulation anomalies associated with the separated time scales. The atmospheric circulation associations on the interannual scale, after removing the interdecadal scale, include the anomalies of geopotential heights and zonal velocities over East Asia, indicating the poleward displacement of the upper-level jet during flood summers. |
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| Keywords: | precipitation North China interdecadal variation interannual variation atmospheric circulaton anomaly |
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