The Peninsular Malaysia Geodetic Vertical Datum 2000 (PMGVD2000) inherited several deficiencies due to offsets between local datums used, levelling error propagations, land subsidence, sea level rise, and sea level slopes along the southern half of the Malacca Strait on the west coast and the South China Sea in the east coast of the Peninsular relative to the Port Klang (PTK) datum point. To cater for a more reliable elevation-based assessment of both sea level rise and coastal flooding exposure, a new epoch-based height reference system PMGVD2022 has been developed. We have undertaken the processing of more than 30 years of sea level data from twelve tide gauge (TG) stations along the Peninsular Malaysia coast for the determination of the relative mean sea level (RMSL) at epoch 2022.0 with their respective trends and incorporates the quantification of the local vertical land motion (VLM) impact. PMGVD2022 is based on a new gravimetric geoid (PMGeoid2022) fitted to the RMSL at PTK. The orthometric height is realised through the GNSS levelling concept H = h^GNSS–N^fit_PTK–N_RMDT, where N_RMDT is a constant offset due to the relative mean dynamic ocean topography (RMDT) between the fitted geoid at PTK and the local MSL datums along the Peninsular Malaysia coast. PMGVD2022 will become a single height reference system with absolute accuracies of better than ±3 cm and ±10 cm across most of the land/coastal area and the continental shelf of Peninsular Malaysia, respectively.

A gravimetric quasi-geoid model, based on the latest FAMOS database release, has been computed for the Baltic Sea region, aiming for a best-possible model on the sea, while not focusing on the surrounding land. The geoid computation is based on the FFT remove-compute-restore method. XGM2019 is used as global reference field, with a Wong-Gore linear tapering from 180 to 200. No terrain corrections are included in the computation, since these are not expected to contribute to the accuracy of the model on the sea.The gravimetric quasi-geoid model is compared to a GNSS-levelled ITRF2008 zero-tide dataset, the altimetry based DTU21 Mean Sea Surface dataset, and to a few tide gauge stations distributed throughout the region. Some preliminary comparisons to the GNSS-levelling dataset indicates that the gravimetric geoid has an accuracy of ±25 mm in the region surrounding the Baltic Sea.

The International Association of Geodesy (IAG) introduced and defined, in 2015, the International Height Reference System (IHRS) as the conventional reference system for the global physical height determination. Following the conventions for the realisation of the IHRS, i.e. the determination of the International Height Reference Frame (IHRF), we utilize the existing GNSS reference stations in Denmark, The Faroe Islands, and Greenland to determine a local densification of the IHRF in these regions. The physical heights of these Danish, Faroese and Greenlandic GNSS reference stations have been transformed from the local Danish, Faroese, and Greenlandic height systems, DVR90, FVR09 and GVR16, respectively, to geopotential numbers and normal heights referring to the IHRF. The offset to the IHRF is found to be −44.0 ± 1.9 cm, −59.8 ± 5.1 cm and − 54.1 ± 11.3 cm for the DVR90, FVR09 and GVR16, respectively. This transformation relies on the existing precise local (quasi-)geoid models. This contribution describes the applied procedures in the IHRF densification and discusses the quality assessment of the results.

The shallow Baltic Sea is a vital waterway with dense shipping traffic, requiring accurate and reliable nautical charts for safe navigation. Until recently, different realisations of the mean sea level were used in the paper charts of each country, sometimes even between harbours. This created obstacles for the digitalisation of ship navigation, including electronic nautical charts combined with satellite-based positioning. To resolve this, the Baltic Sea Hydrographic Commission decided in 2013 to introduce the Baltic Sea Chart Datum 2000 (BSCD2000) as a common height/depth reference system for the maritime sector in the Baltic Sea. The new reference level for all depth and water level information is strictly the quasigeoid, which is practically identical to the geoid at sea. The BSCD2000 is defined in accordance with the European reference systems: the European Terrestrial Reference System 1989 (ETRS89) for ellipsoidal coordinates and the European Vertical Reference System (EVRS) for physical heights. This enables the practical implementation of the zero level through a seamless height transformation grid with standard uncertainties of approximately 1–2 cm, which is harmonised with national coordinates, heights, and height reference surfaces. To the authors’ knowledge, this level of harmonisation is unprecedented in the maritime sector and exemplifies the value of the unification of height systems in geodesy. The paper outlines the foundations of the BSCD2000 and the approach to construct the BSCD2000 height transformation grid. While the computation of the gravimetric marine quasigeoid model is based on well-established methods, special focus is placed on practical harmonisation across national borders and along the coastline. To this end, a novel fitting and blending scheme based on distance maps was developed. Finally, comparison of the new gravimetric marine quasigeoid solution with a preliminary geometric marine geoid model based on SWOT altimetry data and hydrodynamic modelling confirmed good agreement within a few centimetres in most areas of the Baltic Sea.