High spatial and temporal resolution of gravity observations allows quantifying and understanding mass changes in volcanoes, geothermal or other complex geosystems. For this purpose, accurate gravity meters are required. However, transport of the gravity meters to remote study areas may affect the instrument's performance. In this work, we analyse the continuous measurements of three iGrav superconducting gravity meters (iGrav006, iGrav015 and iGrav032), before and after transport between different monitoring sites. For 4 months, we performed comparison measurements in a gravimetric observatory (J9, Strasbourg) where the three iGravs were subjected to the same environmental conditions. Subsequently, we transported them to Þeistareykir, a remote geothermal field in North Iceland. We examine the stability of three instrumental parameters: the calibration factors, noise levels and drift behaviour. For determining the calibration factor of each instrument, we used three methods: First, we performed relative calibration using side-by-side measurements with an observatory gravity meter (iOSG023) at J9. Secondly, we performed absolute calibration by comparing iGrav data and absolute gravity measurements (FG5#206) at J9 and Þeistareykir. Thirdly, we also developed an alternative method, based on intercomparison between pairs of iGravs to check the stability of relative calibration before and after transport to Iceland. The results show that observed changes of the relative calibration factors by transport were less than or equal to 0.01 per cent. Instrumental noise levels were similar before and after transport, whereas periods of high environmental noise at the Icelandic site limited the stability of the absolute calibration measurements, with uncertainties above 0.64 per cent (6 nm s^–2 V^–1). The initial transient drift of the iGravs was monotonically decreasing and seemed to be unaffected by transport when the 4K operating temperatures were maintained. However, it turned out that this cold transport (at 4 K) or sensor preparation procedures before transport may cause a change in the long-term quasi-linear drift rates (e.g. iGrav015 and iGrav032) and they had to be determined again after transport by absolute gravity measurements.

中文翻译：

---

三台iGrav超导重力仪在运往远程监控站点之前和之后的性能

重力观测的高时空分辨率可以量化和了解火山，地热或其他复杂地球系统中的质量变化。为此，需要精确的重力计。但是，将重力仪运输到遥远的研究区域可能会影响仪器的性能。在这项工作中，我们分析了三个iGrav超导重力仪（iGrav006，iGrav015和iGrav032）在不同监测点之间运输前后的连续测量。在四个月的时间里，我们在重力观测站（斯特拉斯堡的J9，J9）中进行了对比测量，其中三个iGrav都经受了相同的环境条件。随后，我们将它们运到冰岛北部偏远的地热田istaeistareykir。我们检查了三个仪器参数的稳定性：校准因子，噪声水平和漂移行为。为了确定每种仪器的校准因子，我们使用了三种方法：首先，我们使用J9上的天文台重力仪（iOSG023）并排测量进行相对校准。其次，我们通过比较iGrav数据和J9和istaeistareykir的绝对重力测量值（FG5＃206）进行了绝对校准。第三，我们还开发了一种替代方法，该方法基于成对的iGravs之间的相互比较，以检查运输到冰岛之前和之后相对校准的稳定性。结果表明，通过运输观察到的相对校准因子的变化小于或等于0.01％。运输前后的仪器噪音水平相似，^–2 V ^–1）。当保持4K工作温度时，iGravs的初始瞬态漂移单调减小，并且似乎不受运输的影响。但是，事实证明，这种冷运输（在4 K下）或运输前的传感器准备程序可能会导致长期准线性漂移率（例如iGrav015和iGrav032）发生变化，必须在运输后再次确定。绝对重力测量。