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1.
模拟的大气角动量函数Ⅰ.季节性分量 总被引：1，自引：0，他引：1
大气角动量（ＡＡＭ）变化和地球自转变化密切相关,它们可应用于全球环流模型的检验,根据日本气象厅全球环流模型的输出数据计算出ＡＡＭ函数,将ＡＡＭ函数的模拟值与它的观测值以及地球自转变化序列相比,来检验该模型对大气角动量的模拟,限于篇幅,仅给出ＡＡＭ函数的季节性分量模拟的结果,对于半年项,轴向ＡＡＭ函数的气压项和风项的模拟值都偏高,赤道向ＡＡＭ函数的气压项和风项很小,因而未予考虑;对于周年项,轴向ＡＡ 相似文献
2.
彭公炳 《中国天文和天体物理学报》1983,(4)
木文根据多年观测资料,计算了各月各层大气南北半球赤道与极地之间和南北半球之间的温度差以及地球自转角速度季节变化值,分析了它们与全球大气角动量以及潮汐引起的日长变化的关系。结果表明,两个半球之间的空气温度差是大气角动量、地球角动量和地球自转角速度产生季节变化的主要原因。 相似文献
3.
用地球自转的历史观测资料反演大气环流的年际变化特征 总被引：2，自引：0，他引：2
郑大伟 《中国科学院上海天文台年刊》1992,(13):1-6
运用近代天和气象观测技术所测得的资料证实了，固体地球自转的速率变化与大气角动量之间，在几年以下的时间尺度上是非常符合的。 因此，本作首先探讨际用历史上的地球自转观测资料序列作为表征大气环流的一种数据的可能性，用多级数字滤波方法反演了过去近三个世纪的大气年际变化过程，并揭示了历史上大气活动的某些特征。 相似文献
4.
用国际地球自转服务提供的高精度日长序列ΔLOD(IERS(EOP99C04),和由美国国家环境预报中心(NCEP)对过去的气象资料进行重新分析和计算,提供的轴向大气角动量序列(AAM)来研究大气和带谐潮汐对地球自转变化(ΔLOD)中高频振荡激发的贡献。由Multitaper功率谱分析表明,ΔLOD序列在9.13d(天)、13.63d、13.66d、27.55d周期时呈现出比较强的谱峰,这些谱都在95%的显著性水平以上,有比较强的信噪比。从ΔLOD和AAM之差值序列谱分析结果及地球带谐响应系数k的估计,表明大气不是ΔLOD的高频变化的主要激发源。根据理论潮汐周期可知,有可能存在其它的激发源,如海洋对地球自转变化的激发。这还有待于进一步深入探讨。 相似文献
5.
用国际地球自转服务提供的高精度日长序列△LOD(IERS(EOP99CO4)，和由美国国家环境预报中心(NCEP)对过去的气象资料进行重新分析和计算，提供的轴向大气角动量序列(AAM)来研究大气和带谐潮汐对地球自转变化(△LOD)中高频振荡激发的贡献。由Multitaper功率谱分析表明，△LOD序列在9．13d(天)、13．63d、13．66d、27．55d周期时呈现出比较强的谱峰，这些谱都在95％的显著性水平以上，有比较强的信噪比。从△LOD和AAM之差值序列谱分析结果及地球带谐响应系数k的估计，表明大气不是△LOD的高频变化的主要激发源。根据理论潮汐周期可知，有可能存在其它的激发源，如海洋对地球自转变化的激发。这还有待于进一步深入探讨。 相似文献
6.
本文用AR谱分析方法分析了1976—1980年地球自转速率的资料和大气环流的资料,以及用调和分析计算了各周期项的振幅及相位,并计算了大气环流的激发函数。其结果说明:两者存在相应的周期项;北半球的大气环流对自转速率周年项的激励约为60％,对半年项及其他短周期项的贡献约为15％以上。本文对自转速率的不规则变化和太阳耀斑大爆发的关系作了定性的比较。 相似文献
7.
地球自转、大气角动量和太阳活动的30—60天波动特征 总被引：1，自引：0，他引：1
本分析了十三年的日长变化、大气角动量和太阳黑子相对数资料，研究了这三种资料序列中30－60天波动过程，用统计分析和检验方法证实这种波动过程在时间尺度上具有随机游动的特性，定量分析表明，在此时间尺度上，大气环流中带风的作用对日长变化的贡献约为87％。如果太阳活动对地球自转中30－60天波动存在激发作用，其作用过程不能完全证明是直接通过大气影响地球自转的。可能存在其他媒介，如通过海洋再作用于大气和固体地球。 相似文献
8.
顾震年 《中国科学院上海天文台年刊》1995,(16):27-34
本文采用国际地球自转服务（IERS）测定的均匀极坐标序列及日本气象局（JMA）提供的大气激发函数赤道分量而求得的激发极移序列来研究它们的半年振荡变化。两种序列进行了比较，相关估计给出x相对于m1的相关系数为0.69，y相对于m2的相关系数为0.52。因此，我们认为大气质量角动量赤道分量对极移半年项有一部分贡献。这些影响表现在x轴方向稍强于y轴方向。结果表明：观测极移和激发极移的半年振荡的周期及振幅都是随时间而变化的。 相似文献
9.
10.
大气相对固体地球的运动产生大气相对角动量，它的变化可以激发地球自转多时间尺度的变化．计算大气相对角动量现在采用两种不同的垂直积分高度，一种为从地形表面积分到顶层大气，称之为SP方法；另一种为从1000hPa积分到顶层大气，称之为BP方法，对采用这两种方法所得到的大气相对角动量进行了详细的比较．应用欧洲中距气象预报中心（ECMWF）和美国国家环境预报中心（NCEP）大气再分析数据，重新研究了大气相对角动量变化的时空特征．通过对大气相对角动量季节平均，季节振幅和时空特征的分析，得出ECMWF和NCEP的大气相对角动量变化对地球自转周年极移的影响，在亚洲季风区域和南极洲区域差别最为明显． 相似文献
11.
12.
Variations of Earth’s rotation rate (length-of-day, LOD) occur over a wide range of time scales from a few hours to the geological age. Studies showed that the 50-day fluctuation exists in LOD change. In the present paper, the authors use wavelet technique to study the 50-day oscillation in LOD series. Temporal variations of the oscillation are presented in this work. After analyzing the axial component of atmospheric angular momentum (AAM) and oceanic angular momentum (OAM), the 50-day periodic signal is also found in atmospheric and oceanic motion with remarkable time-variation. Meanwhile, the 50-day oscillation of the axial AAM is in good consistence with that of LOD change. This suggests that the 50-day oscillation of LOD change is mainly excited by the axial AAM. Possible origin of the oscillation for Earth system is discussed in the end of this paper. 相似文献
13.
Atmospheric angular momentum variations of a planet are associated with the global atmospheric mass redistribution and the wind variability. The exchange of angular momentum between the fluid layers and the solid planet is the main cause for the variations of the planetary rotation at seasonal time scales. In the present study, we investigate the angular momentum variations of the Earth, Mars and Venus, using geodetic observations, output of state-of-the-art global circulation models as well as assimilated data. We discuss the similarities and differences in angular momentum variations, planetary rotation and angular momentum exchange for the three terrestrial planets. We show that the atmospheric angular momentum variations for Mars and Earth are mainly annual and semi-annual whereas they are expected to be “diurnal” on Venus. The wind terms have the largest contributions to the LOD changes of the Earth and Venus whereas the matter term is dominant on Mars due to the CO2 sublimation/condensation. The corresponding LOD variations (ΔLOD) have similar amplitudes on Mars and Earth but are much larger on Venus, though more difficult to observe. 相似文献
14.
Li-Hua Ma Yan-Ben Han National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2006,6(1):120-124
We use the method of wavelet transform to analyze the time series of the Earth's rotation rate of the EOP(IERS)C04.The result shows that the seasonal (annual and semiannual)variation of the length-of-day(LOD)has temporal vari- ability in its period length and amplitude.During 1965.0-2001.0,the periods of the semiannual and annual components varied mainly from 175-day to 190-day and from 360-day to 370-day,respectively;while their amplitudes varied by more than 0.2 ms and 0.1 ms,respectively.Analyzing the axial component of atmospheric angular mo- mentum(AAM)during this period,we have found that time-variations of period lengths and amplitudes also exist in the seasonal oscillations of the axial AAM and are in good consistency with those of the seasonal LOD change.The time variation of the axial AAM can explain largely the change of the LOD on seasonal scales. 相似文献
15.
Applying Vondrák narrow-band filters on high precision Length of Day (LOD) measurements provided by space observation techniques as well as Atmosphere Angular Momentum (AAM) computed by U.S. National Meteorological Center (NMC), we show variation in amplitude of the annual components. From filter series of LOD and AAM, we find that annual variation of the LOD induced by AAM is about 20% higher than observed one. The aim of this work is to investigate how far the torque applied by the solar wind on the Earth's magnetosphere could contribute to explain this excess. The advocated dynamical mechanism could counterbalance annual discrepancies between AAM and LOD by an amount of 20%. Therefore, the torque produced by the solar wind on the earth might be considered as one of the most possible contributions to annual fluctuation in LOD. 相似文献
16.
In the series of the solar activity indices, the zonal component of the atmospheric momentum (AAM), and the Earth rotation variations (UT1-TAI), power spectra concentrations at 40, 50, and 60–80 day period are detected. This result indicates the solar origin of the Madden-Julian oscillation in atmospheric circulation and the 50-day oscillation of the Earth's rotation. 相似文献
17.
大气对地球自转季节性变化的贡献 总被引：2，自引：0，他引：2
采用１９７９－１９９５年期间新的大气角动量资料,研究了大气在季节性时间尺度上对日长变化和极移的贡献。结果表明,考虑了风和大气压的贡献后,大气在周年和半年时间尺度上对日长变化的贡献分别可达９５％和８８％。同时还给出了大气对极移激发的定量结果,其中,大气的周年尺度上对极移Ｘ分同的贡献为１６％,对Ｙ分量的贡献为４３％;在半年尺度上海洋的贡献,才能进上步解决地球自转激发的问题。 相似文献
18.
Temporal Variations in the Second-Degree Stokes Tesseral Geopotential Coefficients from Topex/Poseidon Altimetry 总被引：1，自引：0，他引：1
Burša Milan Kenyon Steve Kouba Jan Ŝíma Zdislav Vatrt Viliam Vítek Vojtêch Vojtíŝková Marie 《Earth, Moon, and Planets》2003,93(1):37-64
The TOPEX/POSEIDON (T/P) altimetry data set covering the periodof January 1, 1993 to January 3, 2001 was used to derive monthlyseries of the second-degree tesseral geopotential coefficients.To account for the sea water temperature variations, rathersimple models have been devised and discussed, describinglocalized as well as areal variations of sea water temperatureand heights. The second-degree tesseral coefficients have alsobeen shown to be proportional to the pressureportions of the oceanic equatorial effective excitation functions,used in Ocean Angular Momentum (OAM) data. OAM datatogether with Atmospheric Angular Momentum (AAM) data canbe used to study observed polar motion (PM) series.The excess PM rates, derived from the T/P effective excitationfunctions, were compared to the corresponding observed PM rates,derived from the International Earth Rotation Service (IERS)Bulletin A and corrected with AAM also obtainedfrom IERS. The noise of the T/P derived PM rate series was foundto be significantly larger than the corresponding Bulletin A/AAMPM rate residuals as well as the PM rates derived from anindependent OAM series that was also available for the1993–2000 period. 相似文献
19.
H. Greiner-Mai 《Astronomische Nachrichten》1990,311(5):317-325
Non-axisymmetric motions of the outer core of the Earth are important for the dynamo problem and the excitation of the decade variations of the polar motion. The components of the vector of a rigid rotation of the outer core about an inclined axis were estimated by a first-order approximation of the frozen- field theory of the geomagnetic secular variation from 1903.5 to 1975.5. The trends and quasi-periodic constituents of these quantities were computed. It was shown that the position and time behaviour of the rotational pole of the outer core differ considerably from the well-know co-ordinates of the dipole axis. Some periods of the equatorial components of the rotational vector are comparable with those of the axial component previously derived for a pure axial rotation. Additionally, the time behaviour of the pole path shows events like the well-known Markowitz wobble but naturally with other extent. These and other results suggested that the investigations are worth to be continued in future by some physical interpretations. 相似文献
20.
Li-Hua Ma De-Chun Liao Yan-Ben Han National Astronomical Observatories Chinese Academy of Sciences Beijing Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 《中国天文和天体物理学报》2006,(6)
We use wavelet transform to study the time series of the Earth's rotation rate (length-of-day, LOD), the axial components of atmospheric angular momentum (AAM) and oceanic angular momentum (OAM) in the period 1962-2005, and discuss the quasi-biennial oscillations (QBO) of LOD change. The results show that the QBO of LOD change varies remarkably in amplitude and phase. It was weak before 1978, then became much stronger and reached maximum values during the strong El Nino events in around 1983 and 1997. Results from analyzing the axial AAM indicate that the QBO signals in axial AAM are extremely consistent with the QBOs of LOD change. During 1963-2003, the QBO variance in the axial AAM can explain about 99.0% of that of the LOD, in other words, all QBO signals of LOD change are almost excited by the axial AAM, while the weak QBO signals of the axial OAM are quite different from those of the LOD and the axial AAM in both time-dependent characteristics and magnitudes. The combined effects of the axial AAM and OAM can explain about 99.1% of the variance of QBO in LOD change during this period. 相似文献