These proceedings contain 27 papers, which are the peer-reviewed versions of presentations made at the International Association of Geodesy (IAG) symposium “Gravity, Geoid and Height Systems 2016” (GGHS2016). GGHS2016 was the first Joint international symposium organized by IAG Commission 2 “Gravity Field”, the International Gravity Field Service (IGFS) and the GGOS Focus Area “Unified Height System”. It took place in Thessaloniki, Greece, in September 19-23, 2016 at the premises of the Aristotle University of Thessaloniki. The symposium was organized by the Department of Geodesy and Surveying of the Aristotle University of Thessaloniki, which presently hosts the IGFS Central Bureau. The focus of the Symposium was on methods for observing, estimating and interpreting the Earth gravity field as well as its applications. GGHS2016 continued the long and successful history of IAG’s Commission 2 Symposia.

These proceedings contain 23 papers, which are the peer-reviewed versions of presentations made at the Joint Scientific Assembly of the International Association of Geodesy (IAG) and the International Association of Seismology and Physics of the Earth’s Interior (IASPEI). The assembly was held from 30 July to 4 August 2017 in Kobe, Japan. The scientific assembly included seven symposia organized by IAG, and nine joint symposia, along with additional symposia organized by IASPEI. The IAG symposia were structured according to the four IAG Commissions and the three GGOS Focus Areas, and included reference frames, static and time-variable gravity field, Earth rotation and geodynamics, multi-signal positioning, geodetic remote sensing, and GGOS. The joint symposia included monitoring of the cryosphere, studies of earthquakes, earthquake source processes, and other types of fault slip, geohazard warning systems, deformation of the lithosphere, and seafloor geodesy. Together, the IAG and joint symposia spanned a broad range of work in geodesy and its applications.

This volume gathers the proceedings of the IX Hotine-Marussi Symposium on Mathematical Geodesy, which was held from 18 to 22 June 2018 at the Faculty of Civil and Industrial Engineering, Sapienza University of Rome, Italy. Since 2006, the Hotine-Marussi Symposia series has been produced under the auspices of the Inter-Commission Committee on Theory (ICCT) within the International Association of Geodesy (IAG). The ICCT has organized the last four Hotine-Marussi Symposia, held in Wuhan (2006) and Rome (2009, 2013 and 2018). The overall goal of the ICCT and Hotine-Marussi Symposia has always been to advance geodetic theory, as reflected in the 25 peer-reviewed research articles presented here. The IX Hotine-Marussi Symposium was divided into 10 topical sessions covering all aspects of geodetic theory including reference frames, gravity field modelling, adjustment theory, atmosphere, time series analysis and advanced numerical methods. In total 118 participants attended the Symposium and delivered 82 oral and 37 poster presentations. During a special session at the Accademia Nazionale deiLincei, the oldest scientific academy in the world, six invited speakers discussed interactions of geodesy with oceanography, glaciology, atmospheric research, mathematics, Earth science and seismology.

This open access volume contains the proceedings of the 5th Symposium on Terrestrial Gravimetry: Static and Mobile Measurements (TG-SMM2019) held in St. Petersburg, Russia, October 1 – 4, 2019. The symposium was hosted by the State Research Center of the Russian Federation Concern CSRI Elektropribor, JSC and was attended by 75 participants from 15 different countries. 32 oral and 20 poster contributions were presented in four different topical sessions: Terrestrial, shipboard and airborne gravimetry, Absolute gravimetry, Relative gravimetry, gravity networks and applications of gravimetry and Cold atom and superconducting gravimeters, gravitational experiments.

These proceedings include selected papers from the International Review Workshop on Satellite Altimetry Cal/Val Activities and Applications, held in Chania, Crete, Greece, on 23-26 April 2018. Organised in the context of the European Space Agency Project “Fiducial Reference Measurements for Altimetry” the workshop was cosponsored by the International Association of Geodesy (in particular by the IAG Commission 2, Gravity Field), the European Space Agency, the European Union (the Copernicus Programme), the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), Space Geomatica P.C., and the Municipality of Chania. The workshop presented the latest research in the field of satellite altimetry calibration and altimetry applications for monitoring ocean changes and improving Earth observation in an objective, continuous, homogeneous and reliable manner, free of errors and biases. Further, it supported long-term monitoring of climate change by providing a better understanding of environmental changes in the world's oceans, terrestrial surface waters, and Arctic and Antarctic Regions. The outcome was the creation of a scientific roadmap with procedures, protocols, guidelines, and best practices to help international groups working on satellite altimetry to establish SI (Système International d'Unités) traceability of their measurements, results and data products.