A new question for the polar motion. What is the origin of phase delay in the gravity response?

极移的新问题。

基本信息

批准号：
11640420
负责人：
SATO Tadahiro
金额：
$ 1.66万
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 (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640420/
关键词：
Gravity changes due to polar motion superconducting gravimeter GGP-Japan Network sea surface height variation satellite altimeter general circulation model of the ocean thermal steric variation 極運動重力応答超伝導重量計年周動力変化海面変動ステリック効果 /

项目摘要

In order to clarify the origin of the phase delay shown in the previous analysis for the polar motion using the superconducting gravimeter data (Sato et al., 1997), the annual gravity changes observed Superconducting Gravimeters (SGs) are examined in relation to Sea Surface Height (SSH) variations. Two SSH data sets from the POCM (Parallel Ocean Climate Model, Stammer et al., 1996) and the TOPEX/POSEIDON (T/P) altimeter were compared. In order to compute the gravity changes due to SSH variations, we firstly estimated the thermal steric coefficient using the Sea Surface Temperature (SST), and we obtained a value of 0.60E-2 m/degC averaged over the central parts of the Pacific and Atlantic oceans. The annual gravity change predicted by considering four effects of the solid tide, ocean tide, polar motion and SSH variations with the observations at the three sites (i.e. Esashi in Japan, Canberra in Australia and Syowa Station in Antarctica). The results of the comparison indicate that the predictions well agree with the observations. Thus, they agree each other within 20% in amplitude (i.e. within 0.2 micro Gaps, where 1 micro Gal=1.E-8 ms^<-2>) and 20 deg in phase at each observation site. We have also tested other values of the steric coefficient, i.e. 0.0E-2 m/degC and 1.0xE-2 m/degC, but we find that the fit to gravity observations made at the mid latitudes is clearly better at 0.60E-2 m/degC.It is noted that our gravity observations point to a value of steric coefficient similar to that independently determined from the relationship between the SSH and SST data. The results obtained here may suggest that the gravity observation can be used to monitor the mass changes in the oceans. This is important to study the coupling mechanism between the Earth's fluid parts and solid parts and to investigate the response of the Earth's system to the polar motion.

为了阐明使用超导重量表数据（Sato等，1997）的先前分析中所示的相位延迟的起源，观察到的年度重力变化与海面高度（SSH）变化有关。比较了POCM（平行海洋气候模型，Stammer等，1996）和Topex/Poseidon（T/P）高度计的两个SSH数据集。为了计算由于SSH变化引起的重力变化，我们首先使用海面温度（SST）估计了热平原系数，并在太平洋和大西洋中部的中部部分获得了0.60e-2 m/deg的值。通过考虑实心潮汐，海潮，极地运动和SSH变化的四种影响，预测的年度重力变化以及三个地点的观察结果（即日本的Esashi，澳大利亚的堪培拉和南极洲的Syowa Station）。比较结果表明，预测与观察值很吻合。因此，他们在20％以内的幅度（即0.2微间隙范围内，1 micro Gal = 1.e-8 ms^<-2>）和在每个观测位点的相位20度之间相互同意。我们还测试了空间系数的其他值，即0.0e-2 m/degC和1.0xe-2 m/deg，但是我们发现，在0.60e-2 m/degc中，在0.60e-e-2 m/degc上进行了对重力观察的拟合度更好。它指出，我们的观测值指出，与STECERCEF的相似之处相似地与该数据相似，并且与该数据相似，并且与该数据相似。这里获得的结果可能表明，重力观察可用于监测海洋的质量变化。这对于研究地球流体部分和固体部分之间的耦合机制并研究地球系统对极性运动的响应很重要。