摘要
将年际时间尺度上的ΔLOD序列 ( 1 958.0 - 1 998.0 )与大气角动量变化 (纬向风 )的激发和SOI等作比较 ,表明大气动力学过程是年际时间尺度ΔLOD变化的重要激发源 ,在实测ΔLOD、纬向风激发和SOI中存在一些相近的频率分量 .但是 ,在实测ΔLOD中有若干很强的信号 (如平均周期约 6.3年 ,平均振幅约 0 .1 3ms的主要分量 ,以及平均周期约 9.0年 ,平均振幅约 0 .0 7ms的分量 )在纬向风激发和SOI中没有检测到 .这表明 ,除了大气动力学过程外 ,还有其他地球物理因素对年际时间尺度的日长变化产生重要的激发作用 .日长年际变化激发源的这一亏缺 。
By using the data of astronomical Δ LOD, the excitation of Δ LOD derived from the wind term of atmospheric angular momentum (AAM), Southern Oscillation Index (SOI) and sea surface temperature (SST) in tropical Pacific on the interannual time scale during 1958-1997, the cross correlation coefficients, phase lags etc. are calculated and shown in Table 1. Their wavelet spectra are shown in Fig.3. Some mean periods as well as their mean amplitudes and phases for the components are shown in Table 2.\;It is shown by comparison that the atmospheric dynamics including the interaction between the atmosphere and tropical oceans is one of the important excitation sources for Δ LOD on the interannual time scale. However, there are some strong signals in Δ LOD (e.g., at the periods about 6.3 and 9.0 years with amplitudes about 0.13 ms and 0.07 ms, respectively), but they have not been detected in the excitation series of AAM and in SOI.\;A brief discussion of the excitation of Δ LOD by continental water storage and non steric mean sea level change on the interannual time scale also shows that the continental water storage and non steric mean sea level change could not balance the budget of the excitation sources of Δ LOD on this time scale. It gives us hints that there exist other excitation sources of Δ LOD on this time scale, and they are worthy of further research.
出处
《天文学报》
CSCD
北大核心
2000年第2期139-147,共9页
Acta Astronomica Sinica
关键词
日长变化
大气角动量变化
南方涛动
厄尔尼诺
variation of length of the day ( Δ LOD), atmospheric angular momentum (AAM), El Nino Southern Oscillation (ENSO)
