The satellite missions GRACE and GRACE Follow-On have undoubtedly been the most important sources to observe mass transport on global scales. Within the Combination Service for Time-Variable Gravity Fields (COST-G), gravity field solutions from various processing centers are being combined to improve the signal-to-noise ratio and further increase the spatial resolution. The time series of monthly gravity field solutions suffer from a data gap of about one year between the two missions GRACE and GRACE Follow-On among several smaller data gaps. We present an intermediate technique bridging the gap between the two missions allowing (1) for a continued and uninterrupted time series of mass observations and (2) to compare, cross-validate and link the two time series. We focus on the combination of high-low satellite-to-satellite tracking (HL-SST) of low-Earth orbiting satellites by GPS in combination with satellite laser ranging (SLR), where SLR contributes to the very low degrees and HL-SST is able to provide the higher spatial resolution at an lower overall precision compared to GRACE-like solutions. We present a complete series covering the period from 2003 to 2022 filling the gaps of GRACE and between the missions. The achieved spatial resolution is approximately 700 km at a monthly temporal resolutions throughout the time period of interest. For the purpose of demonstrating possible applications, we estimate the low degree glacial isostatic adjustment signal in Fennoscandia and North America. In both cases, the location, the signal strength and extend of the signal coincide well with GRACE/GRACE-FO solutions achieving 99.5% and 86.5% correlation, respectively.

GRACE 和 GRACE Follow-On 卫星任务无疑是观测全球范围内公共交通的最重要来源。在时变重力场组合服务（COST-G）中，来自各个处理中心的重力场解决方案被组合起来，以提高信噪比并进一步提高空间分辨率。每月重力场解的时间序列在 GRACE 和 GRACE Follow-On 两个任务之间存在约一年的数据差距，其中还有几个较小的数据差距。我们提出了一种中间技术，弥合了两个任务之间的差距，允许（1）连续不间断的大规模观测时间序列，以及（2）比较、交叉验证和链接两个时间序列。我们专注于通过 GPS 对低地球轨道卫星进行高低星对卫星跟踪 (HL-SST) 与卫星激光测距 (SLR) 的结合，其中 SLR 有助于甚低度和 HL-SST与类似 GRACE 的解决方案相比，它能够以较低的整体精度提供更高的空间分辨率。我们提供了涵盖 2003 年至 2022 年期间的完整系列，填补了 GRACE 以及任务之间的空白。在整个感兴趣的时间段内，每月时间分辨率达到的空间分辨率约为 700 公里。为了演示可能的应用，我们估计了芬诺斯坎迪亚和北美的低度冰川均衡调整信号。在这两种情况下，信号的位置、信号强度和范围都与 GRACE/GRACE-FO 解决方案吻合良好，分别实现了 99.5% 和 86.5% 的相关性。