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数字化水位仪观测的苏门答腊大地震激发的地球球型自由振荡 总被引：2，自引：0，他引：2
利用LN-3型数字化水位仪的观测资料,采用功率谱密度估计方法,在没有对资料进行去固体潮处理的情况下,获得了2004年12月26日苏门答腊大地震激发的0S3～0S30基频球型自由振荡,并检测到2S1、1S2、1S3、2S5和2S6等5个谐频球型振荡,同时记录到一些明显的振型的谱线分裂现象。用水位观测资料提取了0S3、0S4和2S1等3个振型的谱线分裂周期,虽然3个振型均只得到2个单峰,但地球自由振荡谱线分裂现象的检测为研究地球的深内部结构提供了新的、不同类型的观测资料。研究表明,用数字化水位仪的观测资料可以提取到苏门答腊大地震激发的地球球型振荡,为地球自由振荡的研究提供了一种新的观测手段。 相似文献
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用本溪自流井数字化水温观测资料,采用直接计算功率谱密度的方式对印尼苏门答腊9.0级大地震激发的球型自由振荡进行了提取,准确检测到了0S2～0S9低频基型球型振荡,并且还检测到了2个谐频球型振荡:1S2、1S3。用该井数字化水温观测资料提取了0S2、0S3、0S4共3个振型的分裂,虽然3个振型均只得到2个单峰,但地球自由振荡谱线分裂现象的检测为研究地球的深内部结构提供了新的、不同类型的观测资料。研究表明,用本溪自流井数字化水温观测资料可以提取到苏门答腊大地震激发的地球球型振荡,这就为地球自由振荡的研究提供了一种新的观测手段。 相似文献
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汶川大地震激发的地球球型自由振荡 总被引：4，自引：1，他引：3
用垂直摆倾斜仪和水管倾斜仪的数字化观测资料,利用功率谱密度估计方法,在没有对资料进行去固体潮处理的情况下,准确获得了2008年5月12日汶川8.0级大地震激发的0S6～0S32基频球型自由振荡.并与PREM模型的理论自由振荡周期进行了对比,发现实测振荡周期与PREM预测的振荡周期相吻合,除0S7振型的观测周期和PREM模型理论周期的相对误差大于0.3%外,其他振型的观测周期和PREM模型理论周期的相对误差大都集中在0.1%左右.可以从垂直摆倾斜仪和水管倾斜仪的观测资料中提取汶川地震激发的地球球型振荡信息,这为地球自由振荡的研究提供了一种新的仪器观测方法.用数字化地倾斜观测资料研究地球自由振荡问题或许有着较好的前景. 相似文献
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利用怀来地震台水管仪的数字化观测资料,采用功率谱密度估计方法,在没有对资料去固体潮处理的情况下,准确获得2004年12月26日苏门答腊9.0级地震激发的_0S_2—_0S_(38)基频球型自由振荡,并与PREM模型的理论自由振荡周期进行对比,发现实测振荡周期与PREM预测的振荡周期吻合,除_0S_2、_0S_4、_0S_7振型的观测周期和PREM模型理论周期的相对误差大于0.3%外,其他振型的观测周期和PREM模型理论周期的相对误差大都集中在0.1%左右,同时检测到7个谐频球型振荡和10个环型振荡。可以从水管倾斜仪的观测资料中提取地球球型振荡信息,为地球自由振荡的研究提供一种新的仪器观测方法。 相似文献
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利用中国数字地震台网 （CDSN）改造后的7个台站的VHZ波形资料， 提取了2004年12月26日苏门答腊-安达曼地震激发的0S2~0S54地球球型自由振荡，并与地球初步参考模型(PREM)的理论自由振荡频率进行了对比，发现与PREM模型预测的球型自由振荡周期符合得很好. 观测的该地震激发的0S2，0S3，0S4， 2S1和1S2振型自由振荡有明显的频谱分裂现象. 特别是2S1振型，是继Rosat等之后的第二次报道不叠加的情况下观测到的这种振型. 根据该地震的总体震源机制，试算了不同的地震矩，模拟了该地震0S2振型在CDSN 7个台上的自由振荡振幅， 并与记录资料进行了比较，得到该地震的地震矩可达1023Nmiddot;m；本文发现地球自由振荡记录包含了大量震源机制和地震位置的信息， 可用于地震震源破裂参数的精细研究. 相似文献
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利用体应变观测智利8.8级大地震激发的地球球型自由振荡 总被引：2，自引：1，他引：1
用河北省体应变的数字化观测资料,利用功率谱密度估计方法,在没有对资料进行处理的情况下,准确获得了2010年2月27日智利8.8级大地震激发的0S5-0S35摹频球型自由振荡,并与地球初步参考模型(PREM)的理论自由振荡频率进行对比,发现实测振荡频率与PREM预测的振荡频率基本符合.河北省体应变的数字化观测资料的确可以... 相似文献
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将湖州地震台数字伸缩仪线应变观测数据转换成体应变数据,采用功率谱密度估计方法,资料未进行去固体潮处理,准确获得2011年3月11日日本大地震激发的0S4- 0S30基频球型自由振荡,对照PREM模型的理论计算周期,发现观测资料周期与之符合较好. 相似文献
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利用常熟地震台同场地观测的洞体应变仪、体应变仪、水管倾斜仪、垂直摆倾斜仪记录数据,采用小波变换与功率谱密度估计方法,检测2011年3月11日日本9.0级大地震激发的地球自由振荡信号,其中检测到47个球型基频振型（0S3—0S49）、15个环型基频振型（0T5—0T25）以及部分球型谐频振型,与地球初步参考模型（PREM）理论频率值基本符合,表明检测结果较好。对比结果显示：水管倾斜仪检测球型振荡振型能力最强,垂直摆倾斜仪检测环型振荡振型能力最强;体应变仪可检测到清晰的环型基频振型,且信噪比较高;倾斜仪对自由振荡信号的检测能力优于应变仪。 相似文献
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Dynamical mechanism of the stratospheric quasibiennial oscillation impact on the South China Sea Summer Monsoon 总被引：1，自引：0，他引：1
The National Center for the Atmospheric Research (NCAR) middle atmospheric model is used to study the effects of the quasi-biennial oscillation in the stratosphere (QBO) on the tropopause and uppe troposphere, and the relationship between the QBO and South China Sea Summer Monsoon (SCSSM is explored through NCEP (the National Centers for Environmental Prediction)/NCAR, ECMWF (Euro pean Centre for Medium-Range Weather Forecasts) monthly mean wind data and in situ sounding data The simulations show that the QBO-induced residual circulations propagate downwards, and affect the tropopause and upper troposphere during the periods of mid-late QBO phase and phase transition Meanwhile, diagnostic analyses indicate that anomalous circulation similar to SCSSM circulation is generated to strengthen the SCSSM during the easterly phase and anomalous Hadley-like circulation weakens the SCSSM during the westerly. Though the QBO has effects on the SCSSM by meridiona circulation, it is not a sole mechanism on the SCSSM TBO mode. 相似文献
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通过对重力的分析,就极移的自由项(常称为Chandle项)影响做了理论分析,并在此基础上做了进一步计算.表明,Chandle摆动对太原地区的重力影响幅度约为6×10~(-8)m/s~2,且这一影响呈周期变化. 相似文献
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本文根据全球高空10 hPa位势高度距平场EOF分析得知,存在于地面层大气中的南北向涛动现象~北极高空大气涛动和南极涛动,在高空大气中更为清楚,而且这种高空南北向涛动现象是波及全球的;存在于地面层大气中著名的纬向涛动现象~南方涛动(Southern Oscillation,SO)和北方涛动(North Oscillation,NO),在高空大气中则变得不甚清楚.表征北极高空大气涛动的第一模态与表征南极涛动的第二模态的方差贡献率分别为41.47%和27.04%,二者累积方差贡献率达到68.51%,构成了平流层高空大气年代际振荡的主要形式;另外还存在两半球对称性中高纬度南极涛动模态和两半球不对称性中高纬度南极涛动模态,是高空大气中出现概率比较小的振荡形式.谱分析表明,无论北极高空大气涛动模态、南极涛动模态还是中高纬度纬向涛动模态,都存在与太阳磁场磁性指数相一致的22年准周期变化以及与太阳黑子相对数相一致的11年准周期变化;采用逐次滤波法的滤波分析和对比分析表明,高空大气涛动现象的重要影响因子乃太阳活动,其中太阳磁场的大幅度涨落及其磁性变化是主要因素,太阳黑子相对数的变化为次要因素. 相似文献
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我们率先用钻孔应变仪观测资料研究了地球自由振荡. 泰安地震台有差应变和体应变两种钻孔应变观测仪器，都观测到2004年12月26日苏门答腊大地震激发的地球自由振荡. 体应变仪观测到地球的球型振荡，而差应变仪观测到地球的环型振荡. 两种观测还记录到环型振荡与球型振荡相互的耦合作用. 观测也记录到明显的一些振型的谱线分裂现象. 用直接观测到的高质量的环型振荡资料求解了0T8～0T19等主要振型的Q值. 根据两个方向的剪应变观测数据，求解了环型振荡的最大剪应变方向，发现这个方向是相当稳定的. 这种研究表明，高精度钻孔应变观测仪是一种理想的地壳形变观测仪器，可以为地球自由振荡研究提供更丰富的信息. 相似文献
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Using 3 years of high-quality temperature measurements (2002–2004) recorded from Maui, HI (20.8°N), we have investigated the characteristics of mesospheric seasonal oscillations at low-latitudes. Measurements of the near-infrared OH (6,2) and O2 (0,1) nightglow emission layers (centered at 87 and 94 km) independently reveal a distinct semi-annual oscillation (SAO) and annual oscillation (AO) with amplitudes of 3.8 and 2.0 K, respectively. An observed asymmetry in the seasonal variation of the nocturnal mean, previously reported by Taylor et al. [2005. Characterization of the semi-annual-oscillation in mesospheric temperatures at low-latitudes. Advances in Space Research 35, doi:10.1016/j.asr.2005.05.111] from this site is shown to be due to a superposed AO of amplitude 50% of the SAO signature. Detailed investigations of the local-time variation of the SAO amplitude and phase combined with TIME-GCM simulations of the seasonal variation of the diurnal tide strongly suggest a large local-time dependence of the amplitude (but not phase) of the observed SAO. These data indicate that the true mean temperature SAO amplitude could be as high as 7 K at this latitude. 相似文献
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The relationship between the monsoon rainfall throughout all India, northwest India and peninsular India as well as the onset dates of the monsoon and two indices of southern oscillation (SOI), namely Isla de Pascua minus Darwin (I-D) and Tahiti minus Darwin (T-D) pressure anomaly have been studied for different periods. The study indicates that the monsoon rainfall shows a strong and significant direct relationship with SOI for the concurrent, succeeding autumn and succeeding winter seasons. The magnitude of the direct correlation coefficient for the SOI using (I-D) is enhanced over all India and peninsular India if the above seasons happen to be associated with an easterly phase of the QBO (Quasi-Biennial Oscillation) at 50 mb. The result indicates that the strength of the monsoon plays an important role in the following southern oscillation events in the Pacific Ocean. The premonsoon tendency of the SOI anomaly spring minus winter SOI shows a significant positive correlation with monsoon rainfall over all India, northwest India and peninsular India. The absolute value of the positive correlation coefficient becomes highly enhanced over all India, northwest India as well as peninsular India if the 6-month period from December to March is associated with the westerly phase of the QBO. Hence, the premonsoon SOI tendency parameter can be a useful predictor of Indian monsoon rainfall especially if it happens to be associated with the westerly QBO. Significant negative association is also found between the anomaly of monsoon onset dates and SOI of the previous spring season, the absolute value being higher for SOI (T-D) than for SOI (I-D). The negative correlation coefficient becomes enhanced if the previous springs are associated with a westerly phase of the QBO. It shows that the previous spring SOI has some predictive value for the onset date of Indian monsoon, a positive SOI followed by an early onset of monsoon, andvice versa, especially if it is associated with a westerly phase of the QBO. 相似文献
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G.A. Mansilla P. Fernandez de Campra M. Zossi de Artigas 《Journal of Atmospheric and Solar》2009,71(14-15):1610-1612
The aim of this paper is to report some periodicities observed in the ionospheric parameter foF2 measured at Tucuman (26.9°S; 65.4°W), station placed near the southern crest of the equatorial anomaly. For that, monthly medians of foF2 at several hours of LT for the period 1958–1987 are used. The data are run with Fast Fourier Transform (FFT). Data gaps (4–5 months) are filled by means of linear interpolation. Several periodicities are present. Besides the solar cycle dominant dependence (11 years), semi-annual, annual, five years and quasi-biennial periodicities are also observed. A marked quasi-biennial periodicity is observed at daytime and nighttime hours being their greater amplitude at local noon and midnight. Different mechanisms or combined effects possibly cause them. It is suggested that the solar activity by means of extreme ultraviolet radiation (EUV), which present a quasi-biennial oscillation (QBO) and it is responsible for the ionization, could be the dominant mechanism for the diurnal quasi-biennial periodicity of foF2. At night, since the photoionization by extreme ultraviolet radiation is not significant and the F2 layer is lower than during daytime (100 km) other mechanism may be operative for the quasi-biennial periodicity observed. Possibly the stratospheric QBO contributes to the modulation of the observed behaviour in foF2 at night. This result is preliminary because it needs to be extended to other stations so as to extract definite conclusions. Moreover, we cannot dismiss the possibility of a combined effect of both these mechanisms mainly at daytime and/or QBO influence of geomagnetic parameters. 相似文献
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Oscillation characteristics of summer precipitation in the Huaihe River valley and relevant climate background 总被引：1，自引：0，他引：1
WEI FengYing & ZHANG Ting State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences Beijing China 《中国科学:地球科学(英文版)》2010,(2)
Based on the summer precipitation data from the Huaihe River valley and the middle and lower reaches of the Yangtze River from 1922 to 2007,we analyzed the interannual and interdecadal oscillation and probability distribution characteristics of summer precipitation in the Huaihe River valley during the same period,using the wavelet transform and generalized extreme distribution methods.Whereby,we studied the climate background of East Asia Summer Monsoon (EASM),Sea Surface Temperature (SST),East Asia teleco... 相似文献