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271.
用时域分析组合模型建立了100万年来60°N6月份太阳辐射量时间序列、宝鸡黄土粒度时间序列、渭南夏季风指数时间序列的动态模型.研究结果表明,时域分析组合模型较好地提取了时间序列的信息,得到的几个显著周期T=133,100,89,41,23,19ka,与地球轨道三要素的变化周期接近.用组合模型拟合实测数据,精度是高的;用其预测未来气候替代性指标时间序列的变化情况,发现未来气候有向干冷方向发展的趋势.时域分析组合模型为研究气候变化趋势提供了一种定量分析、预测的方法. 相似文献
272.
亚洲季风区是全球热力变化最为显著的区域,亚洲夏季风活动必定会对其它环流系统产生影响。本文通过夏季风指数与北半球环流的相关计算以及强、弱季风候北半球环流异常合成的分析发现,亚洲夏季风的活动会激发北半球夏季大气环流遥相关型,其主要相关中心均出现在季风区的下游地区,即从亚洲经太平洋至北美洲一带,除了表现出正负中心交替出现的波列状结构外,该遥相关型在太平洋地区还表现为一对南北向的偶极子异常型,我们将这一遥相关型称为亚洲太平洋北美(APN)型。 相似文献
273.
树轮密度、稳定C同位素对过去近100a陕西黄陵季节气温与降水的恢复 总被引:7,自引:1,他引:7
相关函数的分析表明,黄陵地区树轮早材最小密度与6月份气温及4~6月份降水显著相关,其相关系数分别为 0.616(α=0.0001)和-0.662(α=0.0001).在此基础上,将早材最小密度指标与稳定C同位素指标采用第一主分量法合并,较精确地重建了黄陵地区6月气温,重建值的解释方差达45%.同时以早材最小密度重建了该区4~6月降水,解释方差达49%.并提出,6月份气温实质上指示了东亚夏季风前锋到达此地时间上的早晚. 相似文献
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278.
珠穆朗玛峰东绒布80.36 m冰芯δ 18O记录的气候意义 总被引:1,自引:0,他引:1
珠穆朗玛峰东绒布80.36 m冰芯δ 18O记录与喜马拉雅山南、北坡气象资料和北半球气温变化之间的关系表明, 该冰芯δ 18O基本上不反映年际温度的变化, 但冰芯δ 18O与净积累量具有负相关关系, 这是该地区夏季降水(占全年降水量的80%以上)中δ 18O“降水量效应”的一种具体表现. 东绒布冰芯δ 18O的变化可作为印度季风活动强弱变化的替代指标. 在季风活动强盛阶段, 冰芯中δ 18O平均值较低; 在季风活动衰弱阶段, 冰芯中δ 18O平均值较高. 相似文献
279.
By using 40-year NCEP reanalysis daily data91958-1997),we have analyzed the climatic characteristics of summer monsoon onset in the South China Sea(1050°E-120°E,5°N-20°N,to be simplified as SCS in the text followed) pentad y pentad(5 days),According to our new definition,in the monsoon area of the SCS two of the following conditions should be satistied:1)At 850hPa,the southwest winds should be greater than 2m/s.2)At 850 hPa.θse should e greater than 335°K.The new definition means that the summermonsoon is the southwest winds high temperature and high moisture.The onset of the SCS summer monsoon is defined to start when one half of the SCS area(105°E-120°E,5°N-20°N)is controlled by the summer monsoon.The analyzed results revealed the following:1) The summer monsoon in the SCS starts to build up abruptly in the 4th pentad in May.2) The summer monsoon onset in the SCS is resulted from the development and intensification of southwesterly monsoon in the Bay of Bengal.3) The onset of the summer monsoon and establishment of the summer monsoon rainfall season in the SCS occur simultaneously.4) During the summer monsoon onset in the SCS,troughs deepen and widen quickly in the lower troposphere of the India:the subtropical high in the Western pacific moves eastward off the SCS in the middle troposphere:the easterly advances northward over the SCS in the upper troposphere. 相似文献
280.
By using the 40-year NCEP(1958-1997) grid point reanalysis meteorological data.we analyzed the inter-decadal variation on the climatic characteristics of the onset of South China Sea summer monsoon.The results are as follows.(1) There was great difference on the onset date of the SCS summer monsoon between the first two decades and the last two decades,It was late on the 6^th pentad of May for the first two decades and was on the 4^th and 5^th pentad of May for the next two decades.(2)Except for the third decade(1978-1987),the establishment of the monsoon rainfall was one to two pentads earlier than the onset of the summer monsoon in all other three decades.(3) The onset of the SCS monsoon is the result of the abrupt development and eastward advancement of the southwesterly monsoon over the Bay of Bengal.The four-decade analysis shows that there were abrupt development of the southwesterly monsoon over the Bay of Bengal between the 3rd and 4th pentad of May,but there was great difference between its ewastward ovement and its onset intensity.These may have important effect to the earlier or later onset of the SCS summer monsoon.(4) During the onset of the SCS summer monsoon.there were great difference in the upper and lower circulation feature between the first two and the next two decades.At the lower troposphere of the first two decades.The Indian-Burma trough was stronger and the center of the subtropical high was located more eastward.At the upper troposphere.the northward movement of the center of subtropical high was large and located more northward after it landed on the lndo-China Peninsula.After comparison.we can see that the circulation feature of the last two decades was favorable to the establishment and development of the SCS summer monsoon. 相似文献