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Basic research on the gravity changes due to the effect of mass variations in the atmosphere and ocean

大气和海洋中质量变化影响引起的重力变化的基础研究

基本信息

批准号：
13440135
负责人：
SATO Tadahito
金额：
$ 9.28万
依托单位：
National Astronomical Observatory
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13440135/
关键词：
Ocean bottom pressure gauge Satellite altimetry Satellite gravimetry Absolute gravimeter Superconducting gravimeter Sea surface height variability Variation in gravity Free core resonance 衛星高度計観測海水面変動による質量移動衛星高度計衛星重力地球重力場の変動

项目摘要

Seafloor pressure monitoring is an indispensable approach to study the effect of seawater mass changes on the Earth's gravity, which also link to the air mass motions. For example, Cox and Chao (2002) claimed the mass exchange in the Pacific Ocean as a major source of the recent rapid and large change in the J2 term of the Earth's gravity may related to the huge ENSO event terminated in the end of 1997. Our group detected the actual pressure changes at that event from the ocean bottom pressure (OBP) observations (Fujimoto et al., Geophysical Research Letters, 2003).Satellite gravimetry (CHAMP and GRACE) is expected to reveal the global relation between the ocean variability and the gravity change. Since 2001, we are carrying out OBP observations at the cross-over points of the TOPEX/Poseidon (TIP) altimeter tracks in the western Pacific Ocean (off Sanriku) in order to investigate the effect of OBP changes on the gravity. We have compared the observations at two sites of OBP-A (about 100 km from sea coast) and OBP-B (about 350 km) with the thee different kinds of data sets. These are (1) the four ocean tide models based on the T/P data, (2) the sea surface height (SSH) variations obtained from the T/P and (3) the pressure changes derived from the ECCO model (Stammer et al., 2002). Our comparison results suggest that it is still needed to carefully examine the effects of ocean mass transportations on the satellite gravimetry which aims at monthly geoid determination at an accuracy of 1 cm or better, and the OBP observation is a useful method for validation of the satellite gravimetry (submitted to GRL).The supper-conducting gravimeter at Esashi well calibrated with the absolute gravimeters have been used to check the tide models and to revise the free core resonance parameters (Sato et al., Journal Geodynamics, 2004, accepted).

海底压力监测是研究海水质量变化对地球重力影响的一种不可或缺的方法，也与大气质量运动有关。例如，考克斯和赵（2002）认为，最近地球重力J2项的快速和大的变化可能与1997年底结束的巨大ENSO事件有关，太平洋的质量交换是一个主要来源。我们的研究小组从海底压力（OBP）观测结果中检测到了该事件的实际压力变化（Fujimoto等人，预计卫星重力测量（CHAMP和GRACE）将揭示海洋变化与重力变化之间的全球关系。从2001年开始，我们在西太平洋三陆近海TOPEX/Poseidon（TIP）测高计航迹交叉点进行了OBP观测，以研究OBP变化对重力场的影响。我们用三种不同的资料对OBP-A（距海岸约100公里）和OBP-B（距海岸约350公里）两个观测站的观测结果进行了比较。它们是（1）基于T/P数据的四个海潮模型，（2）从T/P获得的海面高度（SSH）变化和（3）从ECCO模型（Stammer等人，2002年）。对比结果表明，对于以1cm或更高精度为目标的月大地水准面卫星重力测量，仍需仔细研究海洋质量输运的影响，OBP观测是验证卫星重力测量结果的有效方法（提交GRL）。晚餐-用江ashi的绝对重力仪进行了很好的校准，用来检验潮汐模型和修正自由核共振参数（Sato等人，《地球动力学杂志》，2004年，已接受）。