Final report of EURAMET.M.G-K3 regional comparison of absolute gravimeters

The regional key comparison of absolute gravimeters, EURAMET.M.G-K3 and the simultaneously organized additional comparison, was held in Germany at the Geodetic Observatory Wettzell of the German Federal Agency for Cartography and Geodesy in the spring of 2018.Here we present the list of the participants who actually performed measurements during the comparison, the data submitted by the operators as well as the results of the determination of the gravity as a function of height at the comparison sites. The measurement strategy is briefly discussed and the results of the data harmonization is documented. Finally, the results of the constrained least squares adjustment are presented including the degrees of equivalence of each gravimeter and the key comparison reference values.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).Export citation and abstract BibTeX RIS

The phylogenetic position of the subantarctic marine macroalga Desmarestia chordalis (Phaeophyceae) inferred from nuclear ribosomal ITS sequences

The phylogenetic position of the subantarctic brown macroalga Desmarestia chordalis was inferred from nuclear ribosomal DNA internal transcribed spacer sequences, which were compared with published homologous sequences of putative relatives. According to the molecular data, D. chordalis is closely related to the Antarctic species D. menziesii, and more distantly related to other taxa of similar morphology, i.e. Ant- arctic D. anceps and northern hemisphere D. aculeata

The use of GNSS/levelling and gravity data for the Spanish height system unification

From 2001 to 2008, the National Geographic Institute of Spain (IGN) carried out the REDNAP project to the establishment of a National High Precision Levelling Network in the whole Spanish territory. Within REDNAP, spirit levelling and gravity observations were complemented by GNSS data. The levelling network of the continental area and those of the main islands were referred to different tide gauges thus producing different height systems. In the paper, the GOCO-05S model from the GRACE and GOCE gravity missions is used to unify such systems. More precisely, it is used to estimate the normal heights of the mean sea level at the reference tide gauges, i.e. the height system biases. In the proposed solution such biases are determined through the least squares adjustment of the differences between height anomalies derived from GNSS/levelling and height anomalies derived from a proper combination of global gravity models. An accurate modelling of the observation error covariances is taken into account as well. The estimated accuracies of the resulting biases are in the order of few centimetres apart from that of continental Spain which is an order of magnitude better

Final report of EURAMET.M.G-K3 regional comparison of absolute gravimeters

The regional key comparison of absolute gravimeters, EURAMET.M.G-K3 and the simultaneously organized additional comparison, was held in Germany at the Geodetic Observatory Wettzell of the German Federal Agency for Cartography and Geodesy in the spring of 2018.Here we present the list of the participants who actually performed measurements during the comparison, the data submitted by the operators as well as the results of the determination of the gravity as a function of height at the comparison sites. The measurement strategy is briefly discussed and the results of the data harmonization is documented. Finally, the results of the constrained least squares adjustment are presented including the degrees of equivalence of each gravimeter and the key comparison reference values