A space-time datum which is a reference frame plays an important role in the study of regional gravity field variations. Because gravity values related with different space-time datum will be different, whether the datum is reasonable or not, it has a crucial influence on the measured results of gravity variation. We study the characters of space-time datum, estimate the advantages and disadvantages of applicability for the space-time datum. We also give the standard for rational space-time datum of regional gravity field, which could play a key role in valuing the results of gravity variation. The obtained results will effectively improve the quality of our previous results on gravity variation and lessen the difference between calculated modeling and real situation.%研究区域重力场的变化必须建立一个具有时空意义的参考系统,也就是时空基准.由于变化始终是相对时空基准而言的,选择不同的时空基准就会产生不同的变化结果,因此,时空基准的合理性将直接影响区域重力场变化研究结果的正确性.通过研究基准的时空属性,分析现行时空基准的适用性需求及其优势和缺陷,根据区域重力网的实际情况选建相对合理的时空基准,可在区域重力场变化的分析研究中起到去伪存真的作用,改善目前区域重力场变化的分析结果与研究区的实际情况存在差异的现状.
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