除大气外,海洋对Chandler摆动具有重要的激发作用.利用Estimating the Circulation and Climate of the Ocean(ECCO)的海洋环流模式提供的流速场和洋底压力场资料,首次系统地研究了1980—2005年期间,太平洋、印度洋和大西洋对Chandler摆动激发的贡献.研究表明三大洋对Chandler摆动激发的贡献各不相同,太平洋激发能量约占观测激发能量的22.2%,在三大洋中最高,印度洋约占12.7%,大西洋最低,占7.1%左右.太平洋对Chandler摆动的激发能量可能受1982—1983年强ENSO事件的影响而显著提高.
Plumb line variations(PLV) at Tangshan during the years of 1987―1998 are determined by using the 46 batch repeated gravity observations of the Beijing-Tangshan network.It has been found that PLV at Tangshan are related with the 38 earthquakes in this period.It appears that the time of an earthquake around Tangshan is usually quite the same when PLV at Tangshan begins moving in opposite direction.
LI ZhengXin1,2 & LI Hui3 1 Shanghai Observatory,Chinese Academy of Sciences,Shanghai 200030,China
Real-time rapid prediction of variations of the Earth's rotational rate is of great scientific and practical importance. However, due to the complicated time-variable characteristics of variations of the Earth's rotational rate (i.e., length of day, LOD), it is usually difficult to obtain satisfactory predictions by con-ventional linear time series analysis methods. This study employs the nonlinear artificial neural net-works (ANN) to predict the LOD variations. The topology of the ANN model is determined by minimizing the root mean square errors (RMSE) of the predictions. Considering the close relationships between the LOD variations and the atmospheric circulation movement, the operational prediction series of axial atmospheric angular momentum (AAM) is incorporated into the ANN model as an additional input in the real-time rapid prediction of LOD variations with 1-5 days ahead. The results show that the LOD pre-diction is significantly improved after introducing the operational prediction series of AAM into the ANN model.
