Mean Dynamic Topography Models Research Articles

Application of Geoid and Mean Dynamic Topography Models as an Alternative to the Mean Sea Level Approach in Determining Vertical Datum (Case Study: Java Island and Surrounding)

Abstract Indonesia’s archipelagic territory provides constraints for determining a seamless vertical datum throughout the region. The main constraint is how to connect the vertical datum between islands separated by sea. To define the physical height system of land areas, it usually refers to the Mean Sea Level (MSL), which has different values in each area, and the ideal MSL information is not yet available throughout regions with a minimum data duration of one cycle of 18.6 years. To overcome this constraint, in this research, another alternative method is used: applying a vertical datum that refers to a physical geoid reference surface, namely Mean Dynamic Topography (MDT) using Altimetry satellite data. The study area is Java Island and its surroundings, using vertical information from Geodetic Control Point stations, which also function as Tidal stations in the Indonesian Geospatial Reference System network. The range of MDT deviation values obtained from the Satellite Altimetry with Geodetic Ground Control data is ± 2 meters, which is a good value for coastal areas facing the open sea. This shows that the application of the geoid and MDT models can be used as an alternative, seamless MSL approach in the Java Island region and its surroundings.

Radial surface currents from space: An opportunity for mean dynamic topography estimation?

We analyze the feasibility of so-called radial surface currents as derived from Sentinel-1 Wave mode Doppler shift observations to support the geodetic estimation of the mean dynamic topography (MDT). Broadly defined as subtracting the geoid from the mean sea surface, this separation problem suffers from data inhomogeneities and usually requires strong prior assumptions about the MDT’s smoothness. Recent advancements in calibration and current retrieval methodology for Sentinel-1 data give reason to assess potential gains from this observation type, which can be linked to the gradient of the MDT under geostrophic approximation. Due to current lack of long time-series, we synthesize 10 years of observations from daily surface currents grids and include these in a parametric least-squares adjustment of the MDT. Our results utilizing the synthetic data in place of smoothness constraints are promising, showing 2 cm RMS agreement with a state-of-the-art MDT model.

Evaluating of the accuracy of the DTU22MDT mean dynamic topography model based on the tidal gauge data in Vietnam’s coastal areas

In this study, the accuracy of the latest mean dynamic topography model (MDT), DTU22MDT, is determined based on data collected from 14 tide gauge stations along the coast of Vietnam, from the North to the South. The process of assessing the accuracy of the DTU22MDT model is carried out carefully and precisely, involving determining the model’s height at tide gauge stations, quality checks of the data, and evaluation of the model’s accuracy. The research results indicate that, compared to the local sea surface in Vietnam, the DTU22MDT model has a higher height of approximately 0.7 meters. This model represents the global MDT with the highest accuracy in Vietnam, with a mean square error of about 9.0 cm. This information provides a basis for applying the model in scientific research and practical applications, such as constructing a national height system, planning the economic development of coastal areas, generating specialized maps, designing structures, and other activities in the maritime regions of Vietnam. The method used to evaluate the accuracy of the MDT in this study can be applied to other research areas and to different MDTs.

Reference the seabed topographic depth observations based on the national mean dynamic topography model

The mean sea surface in different regions is non-equipotential, rendering Vietnam's traditional approach, which relies on the Hon-Dau tide gauge station as a reference, not yet scientifically invalid. To overcome this, our study utilized the Vietnam national mean dynamic topography model (MDTVN22) for depth observations, particularly in the Gulf of Tonkin. Covering 3430 monitoring sites in Hai Phong and 813 sites in Quang Ninh, our experiments highlighted a 5 to 6 mm difference between the mean sea surface and MDTVN22 references.•Our research establishes a resilient methodology, integrating shore tide gauge station data and the MDTVN22 model, aimed at enhancing precision in depth observations.•Validation experiments in Hai Phong demonstrate a minimal discrepancy of ±0.006 m between measurements obtained from the traditional mean sea surface and the MDTVN22 model.•These findings underscore the significance of adopting the MDTVN22 model for improved accuracy in assessing Vietnam's seabed topography.

Utilization of Mean Dynamic Topography for GNSS-Leveling Applications (Case Study: Jakarta Area)

Conventionally, the determination of height that has physical meaning for a location or area can be determined geodetically by measuring the height difference relative to a reference point using the spirit-leveling method. This type of height, orthometric height, is essential to explain any physical phenomena, e.g., determining which direction fluid flows, which is used in many scientific and engineering applications. The coverage area is one limitation of conventional leveling, using waterpass precise leveling. The wider the coverage area, the more time and cost-consuming it will be. Another alternative to determine the height at a particular location is using the Global Navigation Satellite System – Leveling (GNSS-Leveling) method, which can be used to resolve the drawbacks of the previous method. GNSS-Leveling method is able to provide an efficient height determination solution if an accurate geoid undulation model and Mean Dynamic Topography (MDT) model are available over the area of interest. MDT is the height deviation between the geoid surface and the mean sea surface (MSS). Information related to geoid undulation and MDT is important to ensure any GNSS-Leveling measurement referring to the local Mean Sea Level (MSL) surface, which is widely needed in various applications. Applying the EGM2008 geoid model and altimetric-derived MDT solution to GNSS-Leveling measurements in the Jakarta area, the average orthometric height difference relative to the reference value is estimated to be about 5 cm. This shows that GNSS-Leveling is a promising solution when combined with geoid and MDT models.

Определение гравитационных аномалий в акватории Вьетнама и на прилегающей территории по данным спутниковой альтиметрии CryoSat-2

The purpose of this study is to determine marine gravity anomalies with high accuracy using the CryoSat-2 satellite altimetry data in the Middle Vietnamese Sea and the adjacent territory. For this, the mentioned data and the process of determining gravity anomalies from the CryoSat-2 data were analyzed. The record from 818 GNSS-leveling points in Vietnam were used to evaluate and select the best global gravity field model for use in the calculation process. The findings from 31 gauge tidal were also used to assess and select the best mean dynamic topography model for the study area. Marine gravity anomalies in the study area were calculated using data from the CryoSat-2 satellite altimeter at 72 483 measurement points. The calculated results are compared with the ship-derived gravity anomalies at 1025 measurement points for assessment. The research results show that of the Earth Geopotential Model EIGEN6C4 and the Mean Dynamic Topography Model DTU15MDT are the most suitable for the research area. The accuracy of satellite-derived gravity anomalies, calculated from the CryoSat-2 satellite altimetry data in the study area, reaches ±1,18 mGal. Compared to the available results in the study area, this accuracy is the highest.

Regional Mean Sea Surface and Mean Dynamic Topography Models Around Malaysian Seas Developed From 27 Years of Along-Track Multi-Mission Satellite Altimetry Data

Contemporary Universiti Teknologi Malaysia 2020 Mean Sea Surface (UTM20 MSS) and Mean Dynamic Topography (UTM20 MDT) models around Malaysian seas are introduced in this study. These regional models are computed via scrutinizing along-track sea surface height (SSH) points and specific interpolation methods. A 1.5-min resolution of UTM20 MSS is established by integrating 27 years of along-track multi-mission satellite altimetry covering 1993–2019 and considering the 19-year moving average technique. The Exact Repeat Mission (ERM) collinear analysis, reduction of sea level variability of geodetic mission (GM) data, crossover adjustment, and data gridding are presented as part of the MSS computation. The UTM20 MDT is derived using a pointwise approach from the differences between UTM20 MSS and the local gravimetric geoid. UTM20 MSS and MDT reliability are validated with the latest Technical University of Denmark (DTU) and Collecte Localisation Services (CLS) models along with coastal tide gauges. The findings presented that the UTM20, CLS15, and DTU18 MSS models exhibit good agreement. Besides, UTM20 MDT is also in good agreement with CLS18 and DTU15 MDT models with an accuracy of 5.1 and 5.5 cm, respectively. The results also indicate that UTM20 MDT statistically achieves better accuracy than global models compared to tide gauges. Meanwhile, the UTM20 MSS accuracy is within 7.5 cm. These outcomes prove that UTM20 MSS and MDT models yield significant improvement compared to the previous regional models developed by UTM, denoted as MSS1 and MSS2 in this study.

The parameterization of mean dynamic topography based on the Lagrange basis functions

The filtering procedure is usually mandatory for computing the mean dynamic topography (MDT) by combining the mean sea surface (MSS) and geoid due to the inconsistent spectral contents between them. Recently, a rigorous fusion method is proposed to solve this inconsistency problem through the least square method (Becker et al., 2012), where MDT is parameterized by the Lagrange basis functions (LBFs). In this study, the latest CNES-CLS18MDT with its associated error information is introduced for the parameterization experiments, where the LBFs consist of 4, 16, and 36 polynomial parameters (4P/16P/36P) are implemented and compared, respectively. The experiments are conducted in two research areas close to the Kuroshio and Gulf Stream. Besides, two oceanographic, two geodetic MDT models, and the average of the above models are introduced as the comparison data to assess their respective agreement with the recovered MDT based on LBFs. Results show that the standard deviation (SD) of the misfits from the results of 16P against the mean MDT is 2.6 cm (Kuroshio current) and 6.8 cm (Gulf stream), respectively. Compared with the 4P/36P, the 16P reduced the misfits in these two regions by 0.8–1.1 cm and 0.3–0.5 cm, respectively. The misfits between the results using 16P and the MDT models are ~5 cm lower than that using 4P/36P in regions with a strong variation of ocean current. In total, the 16P is more favorable in representing the characteristics of MDT and has a better versatility when parameterizing MDT under different ocean states.

Marine gravity anomaly mapping for the Gulf of Tonkin area (Vietnam) using Cryosat-2 and Saral/AltiKa satellite altimetry data

Marine gravity anomalies are essential data for determining coastal geoid, investigating tectonics and crustal structures, and offshore explorations. The objective of this study is to present a methodology for estimating marine gravity anomalies from CryoSat-2 and Saral/AltiKa satellite altimeter data for the Gulf of Tonkin of Vietnam with a high-resolution 2′ × 2′ grid. A total of 15,665 sea surface height (SSH) grid points, including derived from the Cryosat-2 (6842 grid points) and Saral/AltiKa (8823 grid points) satellite altimeter data were used. Then, the remove-restore technique and the crossover adjustment algorithm were used to remove the long-wavelength geoid height, the mean dynamic topography hMDT, and time-varying sea-surface topography ht. The residual geoid heights ΔN were used to determine the residual gravity anomalies δg using the Least-Squares Collocation method, whereas the Earth Geopotential Model was employed to restore the long-wavelength gravity anomalies ΔgEIGEN. GPS/leveling and tidal gauge of 31 tidal stations were used for assessing and choosing the best Earth Geopotential Model and Mean Dynamic Topography models for the study area (EIGEN6C4 and DTU15MDT models). The accuracy of the final marine gravity anomaly result was assessed using 56,978 marine gravity points, which were distributed in the study area. The result showed that the standard deviation between the satellite-derived gravity anomalies and checked points is ± 3.36 mGal, indicating good accuracy. After improving with ship-measured gravity anomalies, the accuracy of satellite-derived marine gravity anomaly improves to ± 2.63 mGal. The results of this research are useful for geodetic and geophysical applications in the region.

Mean sea surface and mean dynamic topography determination from Cryosat-2 data around Australia

In this study, we use seven years of Cryosat-2 data to improve Mean Sea Surface (MSS) and also to estimate Mean Dynamic Topography (MDT) around Australia. Sea Level Anomaly (SLA) map, obtained from Cryosat-2 data, shows substantial spatial striping effects in the areas where annual signal has considerable amplitudes. This signal causes shifts among the SLAs acquired from adjacent tracks since they have collected at different times of the year. In order to mitigate these effects, we used Topex/Poseidon and follow on missions to estimate the seasonal signals in the Cryosat-2 data points. MSSC2 is then estimated by (1) removing these signals from SLAs, (2) averaging in a 0.1° × 0.1° grid cells, and (3) finally adding them to the DTUMSS13. The resultant surface shows good agreement with the MSS estimated by Jason-1 and Jason-2 data in altimetry nominal points. MDTC2 is also estimated in the study area using the MSSC2 and the geoid. It is in good agreement with two widely used global MDT models although showing higher values due to the effect of sea-level rise. When compared to the estimated MDT in tide gauge stations using geodetic data, MDTC2 statistically performs better than the global models.

A new ocean mean dynamic topography model, derived from a combination of gravity, altimetry and drifter velocity data

Abstract We present a new mean dynamic ocean topography product based on the improved geoid model, derived in the Optimal Geoid for Modelling Ocean Circulation (OGMOC) project supported by the European Space Agency. This geoid model is based on the Gravity Recovery and Climate Experiment (GRACE) and the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite missions combined with the newer DTU15GRA altimetric surface gravity and it was optimized to eliminate artificial features common for other geoid models such as striations and orange skin. Subsequently, the model has been augmented using the EIGEN-6C4 coefficients to harmonic degree 2160. The new geodetic mean dynamic ocean topography model DTU17MDT has been derived using this geoid model and the DTU15MSS mean sea surface, with the quasi-gaussian filter optimized to best fit velocities of oceanographic drifting buoys. The new model improves the resolution of important details of the ocean circulation. Finally, the drifter data were integrated into the model to refine its spatial resolution. The new topography product DTU17cMDT, combining the wealth of information from satellite gravity and altimetry and drifters, is rich with more features of the ocean surface circulation. In particular, as shown in the case of the Gulf Stream off the east coast of Florida, DTU17cMDT improves description of the western boundary currents.

A global vertical datum defined by the conventional geoid potential and the Earth ellipsoid parameters

The geoid, according to the classical Gauss–Listing definition, is, among infinite equipotential surfaces of the Earth’s gravity field, the equipotential surface that in a least squares sense best fits the undisturbed mean sea level. This equipotential surface, except for its zero-degree harmonic, can be characterized using the Earth’s global gravity models (GGM). Although, nowadays, satellite altimetry technique provides the absolute geoid height over oceans that can be used to calibrate the unknown zero-degree harmonic of the gravimetric geoid models, this technique cannot be utilized to estimate the geometric parameters of the mean Earth ellipsoid (MEE). The main objective of this study is to perform a joint estimation of W0, which defines the zero datum of vertical coordinates, and the MEE parameters relying on a new approach and on the newest gravity field, mean sea surface and mean dynamic topography models. As our approach utilizes both satellite altimetry observations and a GGM model, we consider different aspects of the input data to evaluate the sensitivity of our estimations to the input data. Unlike previous studies, our results show that it is not sufficient to use only the satellite-component of a quasi-stationary GGM to estimate W0. In addition, our results confirm a high sensitivity of the applied approach to the altimetry-based geoid heights, i.e., mean sea surface and mean dynamic topography models. Moreover, as W0 should be considered a quasi-stationary parameter, we quantify the effect of time-dependent Earth’s gravity field changes as well as the time-dependent sea level changes on the estimation of W0. Our computations resulted in the geoid potential W0 = 62636848.102 ± 0.004 m2 s−2 and the semi-major and minor axes of the MEE, a = 6378137.678 ± 0.0003 m and b = 6356752.964 ± 0.0005 m, which are 0.678 and 0.650 m larger than those axes of GRS80 reference ellipsoid, respectively. Moreover, a new estimation for the geocentric gravitational constant was obtained as GM = (398600460.55 ± 0.03) × 106 m3 s−2.

The coastal mean dynamic topography in Norway observed by CryoSat‐2 and GOCE

AbstractNew‐generation synthetic aperture radar altimetry, as implemented on CryoSat‐2, observes sea surface heights in coastal areas that were previously not monitored by conventional altimetry. Therefore, CryoSat‐2 is expected to improve the coastal mean dynamic topography (MDT). However, the MDT remains highly reliant on the geoid. Using new regional geoid models as well as CryoSat‐2 data, we determine three geodetic coastal MDT models in Norway and validate them against independent tide‐gauge observations and the operational coastal ocean model NorKyst800. The CryoSat‐2 MDTs agree on the ∼3–5 cm level with both tide‐gauge geodetic and ocean MDTs along the Norwegian coast. In addition, we compute geostrophic surface currents to help identifying errors in the geoid models. We find that even though the regional geoid models are all based on the latest satellite gravity data as provided by GOCE, the resulting circulation patterns differ. We demonstrate that some of these differences are due to erroneous or lack of marine gravity data. This suggests that there is significant MDT signal at spatial scales beyond GOCE, and that the geodetic approach to MDT determination benefits from the additional terrestrial gravity information provided by a regional geoid model. We also find that the border of the geographical mode mask of CryoSat‐2 coincides with the Norwegian Coastal Current, making it challenging to distinguish between artifacts in the CryoSat‐2 observations during mode switch and ocean signal.

Using Models of the Ocean's Mean Dynamic Topography to Identify Errors in Coastal Geodetic Levelling

Identifying errors (blunders and systematic errors) in coastal geodetic levelling networks has often been problematic, primarily for two reasons. First, mean sea level (MSL) at tide gauges cannot be directly compared to height differences from levelling because the geoid/quasigeoid and MSL are not parallel, being separated by the ocean's mean dynamic topography (MDT). Second, there is a the lack of redundancy at the edge of the levelling network. This article sets out a methodology to independently identify blunders and/or systematic errors (over long distances) in geodetic levelling using MDT models to account for the separation between the geoid/quasigeoid and MSL at tide gauges. This method is then tested in a case study using an oceanographic MDT model, MSL observations, GNSS data, and a quasigeoid model. The results are significant because the errors found could not be detected by standard levelling misclosure checks alone, with supplementary data from an MDT model, with cross-validation from GNSS-quasigeoid allowing their detection. In addition, it appears that an oceanographic-only MDT is as effective as GNSS and a quasigeoid model for detecting levelling errors, which could be particularly useful for countries with coastal levelling errors in their levelling networks that cannot be identified by conventional levelling closure checks.

A Tailored Computation of the Mean Dynamic Topography for a Consistent Integration into Ocean Circulation Models

Geostrophic surface velocities can be derived from the gradients of the mean dynamic topography—the difference between the mean sea surface and the geoid. Therefore, independently observed mean dynamic topography data are valuable input parameters and constraints for ocean circulation models. For a successful fit to observational dynamic topography data, not only the mean dynamic topography on the particular ocean model grid is required, but also information about its inverse covariance matrix. The calculation of the mean dynamic topography from satellite-based gravity field models and altimetric sea surface height measurements, however, is not straightforward. For this purpose, we previously developed an integrated approach to combining these two different observation groups in a consistent way without using the common filter approaches (Becker et al. in J Geodyn 59(60):99–110, 2012; Becker in Konsistente Kombination von Schwerefeld, Altimetrie und hydrographischen Daten zur Modellierung der dynamischen Ozeantopographie 2012). Within this combination method, the full spectral range of the observations is considered. Further, it allows the direct determination of the normal equations (i.e., the inverse of the error covariance matrix) of the mean dynamic topography on arbitrary grids, which is one of the requirements for ocean data assimilation. In this paper, we report progress through selection and improved processing of altimetric data sets. We focus on the preprocessing steps of along-track altimetry data from Jason-1 and Envisat to obtain a mean sea surface profile. During this procedure, a rigorous variance propagation is accomplished, so that, for the first time, the full covariance matrix of the mean sea surface is available. The combination of the mean profile and a combined GRACE/GOCE gravity field model yields a mean dynamic topography model for the North Atlantic Ocean that is characterized by a defined set of assumptions. We show that including the geodetically derived mean dynamic topography with the full error structure in a 3D stationary inverse ocean model improves modeled oceanographic features over previous estimates.

Analysis of a relative offset between vertical datums at the North and South Islands of New Zealand

The leveling networks realized by 13 different local vertical datums were jointly readjusted at the South and North Islands of New Zealand. The relation between these two leveling networks and the Word Height System was then defined using GPS-leveling data and the EGM08 global geopotential model. In this study, we investigate the relative offset between these two vertical datum realizations. This is done based on comparison of the geometric geoid/quasigeoid heights (obtained from GPS and newly adjusted leveling data) with the regional gravimetric geoid/quasigeoid solutions. Moreover, oceanographic and geodetic models of mean dynamic topography (MDT) are used to assess the relative offset between these two vertical datum realizations through the analysis of regional spatial variations of mean sea level (MSL). The comparison of GPS-leveling data with regional gravimetric solutions re- veals large systematic distortions (exceeding several deci- meters across New Zealand) between the geometric and gravimetric geoid/quasigeoid heights attributed mainly to systematic errors within regional gravimetric solutions. The presence of a significant offset between the vertical datum realizations at the North and South Islands is not confirmed. The MSL difference between tide gauges in Wellington and Dunedin of ∼24 cm is estimated based on the analysis of MDT models.

Rigorous fusion of gravity field, altimetry and stationary ocean models

Many characteristics of the ocean circulation are reflected in the mean dynamic topography (MDT). Therefore observing the MDT provides valuable information for evaluating or improving ocean models. Using this information is complicated by the inconsistent representation of MDT in observations and ocean models. This problem is addressed by a consistent treatment of satellite altimetry and geoid height information on an ocean model grid. The altimetric sea surface is expressed as a sum of geoid heights represented by spherical harmonic functions and the mean dynamic topography parameterized by a finite element method. Within this framework the inversion and smoothing processes are avoided that are necessary in step-by-step approaches, such that the normal equations of the MDT can be accumulated in a straightforward way. Conveniently, these normal equations are the appropriate weight matrices for model-data misfits in least-squares ocean model inversions. Two prototypes of these rigorously combined MDT models, with an associated complete error description including the omission error, are developed for the North Atlantic Ocean and assimilated into a 3D-inverse ocean model. The ocean model solutions provide evidence that satellite observations and oceanographic data are consistent within prior errors.

Mean Sea Surface and ocean circulation in North Atlantic and the Arctic Sea

High resolution Mean Sea Surface (MSS) model and its error estimation over the study region (56°N<ϕ<82°N, 45°W<λ<33°E) have been determined to evaluate Mean Dynamic Topography (MDT) in the Fram Strait and adjacent seas. Multiple high-latitude observing satellite radar altimetry data were used to determine a new MSS model that, hereafter, is called NTNU MSS. Sea Surface Height (SSH) values of the NTNU MSS model vary between 15 to 70 m over the study region, and the internal consistency or the quality estimate for the model ranges from 1 to 5 cm. External comparisons have been performed to validate the NTNU model applying available MSS models such as KMS04, mean and Standard Deviations (SD) of the differences are 1.7 cm and 8.9 cm, respectively. To assess the compatibility of the NTNU MSS model, residual analysis has been carried out relative to geoid and Oceanographic MDT (OMDT) models. Utilizing OCTAS04 geoid and OCCAM MDT models, the SD and mean of the residuals are 13.1 cm and 10.1 cm, respectively. Finally, the surface geostrophic velocities have been computed and compared with the velocities extracted from the OCCAM and KMS04. Differences between the geostrophic velocities derived from the NTNU Synthetic MDT (SMDT) and the OCCAM OMDT are 4.97 and 2.94 cm/s for the mean and SD values.

Mean mesoscale global ocean currents from geodetic pre‐GOCE MDTs with a synthesis of the North Pacific circulation

A new milestone in satellite geodesy is about to be completed with the expected availability of the high‐resolution data from the already in‐orbit Global Ocean Circulation Explorer (GOCE) satellite. There are still some open questions related to capability of recovering mean mesoscale (50 km plus) geostrophic circulation (MGC) patterns from observational Gravity Recovery and Climate Experiment (GRACE)‐based geodetic Mean Dynamic Topography (MDTs), which we examine here in detail. A new set of global geodetic MDTs with high grid resolutions was computed (0.1° and 0.25°) based on the newest EGM08 and GRACE GGM02 geoid models. The high resolution coupled to good mesoscale feature discrimination was derived using efficient filtering procedure based on singular spectrum analysis. The new solutions were contrasted with five important MDTs, including the hybrid and the geodetic MDTs, through empirical orthogonal functions analysis, which permit the determination of the mutual correlation among the MDTs, and establishment of error bounds. The methodology made viable a detailed and robust analysis of the North Pacific Ocean circulation based on these MGCs including comparisons with known results from other studies. We prove the superiority of the geodetic EGM08 (as opposed to hybrid) MDT models by obtaining less noisy and more intense and slender western boundary currents and their recirculations, the bifurcations at the Shatsky Rise, and the known mean eddies in the low‐latitude shear region (NEC‐NECC).

DNSC08 mean sea surface and mean dynamic topography models

The Danish National Space Center data set DNSC08 mean sea surface (MSS) is a new enhanced mapping of the mean sea surface height of the worlds oceans, derived from a combination of 12 years of satellite altimetry from a total of eight different satellites covering the period 1993–2004. It is the first global MSS without a polar gap including all of the Arctic Ocean by including laser altimetry from the ICESat mission. The mean dynamic topography (MDT) is the quantity that bridges the geoid and the mean sea surface constraining large‐scale ocean circulation. Here we present a new high‐resolution 1 min global MDT called DNSC08 MDT derived from the slightly smoothed difference between the DNSC08 MSS and the EGM2008 geoid. The derivation and quality control of the new DNSC08 MSS and DNSC08 MDT is presented in this paper along with suggestions for time period standardization of the MSS and MDT models. This way a consistent modeling of the interannual sea level variability is carried out before different MSS and MDT models are compared. Altimetric derived physical MSS can be converted into an “inverse barometer corrected MSS” by correcting the altimeter range for the inverse barometer effect of the atmosphere on the sea surface height. It is demonstrated that it is important to choose the right version of the MSS when comparing with hydrodynamic models and GPS measured tide gauges.