Abstract

The Global Positioning System (GPS) permanent stations at the equatorial and southern sub-tropical hydrobelts of South America undergo the highest seasonality on the Earth due to hydrological loadings. Fortunately, there are products that account for such variations, although some of them have not been properly evaluated. For instance, global solutions of Gravity Recovery and Climate Experiment (GRACE) are band-limited to lower frequencies; therefore, comparisons with GPS data must account for such spectral inconsistencies. It is proposed to spatially average 39 GPS sites by applying Gaussian smoothing, which allows comparisons with long-wavelength part of GRACE solutions by Center for Space Research (CSR), GeoForschungszentrum, and Jet Propulsion Laboratory. Comparisons are also carried out with loadings from Noah-driven Global Land Data Assimilation System (GLDAS) and GRACE mass concentration (mascon) solution by Goddard Space Flight Center. Results show that CSR best reduces the variances of the radial displacements considering both spatially filtered (70%) and unfiltered (53%) GPS data covering the period from Jan 2010 to Dec 2015. However, GLDAS-Noah underestimates the amplitudes of vertical loadings, which might be due to unmodeled inland water and groundwater storages. While acknowledging that a denser distribution of GPS stations is needed, the findings still shed light on the quality of the global hydrological loading products based on GRACE and GLDAS datasets, which might be of interest to the respective science teams.

Graphic abstract

中文翻译：

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大地测量和建模的垂直水文荷载产品的倒数比较

摘要

由于水文负荷，​​南美洲的赤道和南部亚热带水带的全球定位系统（GPS）永久站在地球上的季节性最高。幸运的是，有一些产品可以解释这种差异，尽管其中一些尚未得到正确评估。例如，重力恢复和气候实验（GRACE）的全球解决方案将频带限制为较低的频率；因此，与GPS数据的比较必须解决这种频谱不一致的问题。建议通过应用高斯平滑对39个GPS站点进行空间平均，从而可以与GeoReschungszentrum空间研究中心（CSR）的GRACE解决方案的长波长部分进行比较和喷气推进实验室。戈达德太空飞行中心还对由诺亚（Noah）驱动的全球土地数据同化系统（GLDAS）和GRACE质量浓度（mascon）解决方案中的负荷进行了比较。结果表明，考虑到从2010年1月到2015年12月这段时间的GPS数据经过空间滤波（70％）和未滤波（53％），CSR可以最大程度地减小径向位移的方差。但是，GLDAS-Noah低估了垂直荷载的振幅，这可能是由于未建模的内陆水和地下水存储所致。在承认需要更密集地分布GPS站的同时，研究结果仍然阐明了基于GRACE和GLDAS数据集的全球水文负荷产品的质量，这可能是各个科学团队感兴趣的。

图形摘要