由于观测、参考架、模型、时间尺度精度的不断提高和完善,国际天球参考系(ICRS)被引入使用, IAU 2000年大会决定从2003年起采用新的天球中介极(CIP)、新的天球中介原点(CIO)、新的岁差-章动模型和新的UT1定义等,并定义了新的中介的运动参考架,由此给天体测量学带来很大的影响,天体测量学的内容和实践发生了许多重要的变化。据此,对天体测量学的术语、概念和定义的变化作了描述,并讨论了变化的原因和对天体测量学的影响。新的一套天体测量理论和方法正在变更之中,我们应及时跟上这个领域的发展步伐。
Using the length-of-day (LOD) data series de-rived from astronomical observations made by various mod-ern space techniques, southern oscillation index (SOI) and anomalies of sea surface temperature (SST) in tropical Pa-cific Ocean, the inter-annual components of these data series are obtained by the technique of band filtering from January 1962 to October 2002. It is found that a new ENSO event has already occurred in 2002 and been detected by the inter- annual LOD. It is shown by the wavelet analysis that the component with a period of about 46 years and the quasi-biennial component are out of phase during 2001 2002, which consequently suggests that the new ENSO event cannot be a strong one.
