WET-CAG2021: An international comparison of absolute gravimeters for the realization of the International Gravity Reference System

<p>Geodetic observations on Earth accurate to better than a part per billion require a common reference for the same precision as described in the goals of the Global Geodetic Observing System. The International Gravity Reference System (IGRS) is proposed as a new reference for terrestrial gravity observations (Wziontek et al. 2021).</p><p>The International Gravity Reference Frame (IGRF) as the realization of IGRS is represented by absolute gravity measurements traceable to the SI. Due to the lack of a natural reference, absolute gravimeters need to be compared and the gravity reference is realized based on a set of measurements by a group of absolute gravimeters and the functional model for their processing.</p><p>We present the international comparison of absolute gravimeters WET-CAG2021 hosted at the Geodetic Observatory Wettzell in autumn 2021. This comparison is classified as an additional comparison following the strategy paper of the Consultative Committee for Mass and related quantities (CCM) and IAG. Seven FG5/X absolute gravimeters and two AQG quantum gravimeters have observed up to four individual piers over a period of twelve weeks. The individual observation epochs are connected by recordings of the continuously operating superconducting gravimeter GWR OSG 030 in the same laboratory.</p><p>We show the procedure of data analysis following P&#225;link&#225;&#353; et al. (2021) and discuss the results also with respect to the latest regional metrological EURAMET comparison 2018 at the same location.</p><p>&#160;</p><p>Marti, U., Richard, P., Germak, A., Vitushkin, L., P&#225;link&#225;&#353;, V., Wilmes, H.: CCM-IAG Strategy for Metrology in Absolute Gravimetry, 11 March 2014</p><p>P&#225;link&#225;&#353;, V., Wziontek, H., Va&#318;ko, M. et al.: Evaluation of comparisons of absolute gravimeters using correlated quantities: reprocessing and analyses of recent comparisons. <em>J Geod</em> 95,<strong> </strong>21 (2021). https://doi.org/10.1007/s00190-020-01435-y</p><p>Wziontek, H., Bonvalot, S., Falk, R. et al.: Status of the International Gravity Reference System and Frame. <em>J Geod</em> 95, 7 (2021). https://doi.org/10.1007/s00190-020-01438-9</p>