Denise Dettmering

Technical University of Munich | TUM · Deutsches Geodätisches Forschungsinstitut

Sea level variations in the coastal zone can differ significantly from those in the open ocean and can be highly spatiotemporally coherent in the alongshore direction. Yet, where and how coastal sea levels exhibit variations that emerge as persistent and recurrent patterns along the world's coastlines remain poorly understood. Here, we use a Bayesi...

Plain Language Summary Estimating ocean tides in the coastal region has challenged tide modelers for decades. The recently launched SWOT satellite provides the opportunity to derive estimations of ocean tides at unprecedented spatial scales thanks to the innovative wide‐swath measurement principle, particularly in complex coastal regions. The missi...

While difficult accessibility leads to a lack of oceanographic in-situ measurements in the Arctic Ocean, and in particular in the Chukchi Sea, satellite altimetry provides precise information on the sea surface at different spatial and temporal scales and can be used for studies of current patterns. Here, we created a novel long-term altimetry-base...

Satellite radar altimetry has been providing sea surface heights on an almost global scale for the past 30 years. From this data, an average global mean sea level rise of 3-4 mm per year can be estimated. To determine these small changes with high accuracy, precise and stable measurements are required. Long-term data stability is particularly impor...

We have analyzed the relationship between wind variability and sea level anomalies (SLA) on the Southwestern Atlantic Continental Shelf, focusing on sub-annual temporal scales. For this, we tested the capability of gridded altimetry to represent wind-driven SLA and compared results using an oceanographic model and tide gauge data. The present study...

Studying ocean tides with satellite altimetry has traditionally been difficult in coastal regions. The 1-day repeat of the Cal/Val phase of SWOT provides a unique dataset that can be exploited for tidal analysis. In this work, KaRIn data from the SWOT Cal/Val phase are analysed in two coastal regions to present a first look at the possibilities for...

Vertical land movements can cause regional relative sea-level changes to differ substantially from climate-driven absolute sea-level changes. Whereas absolute sea level has been accurately monitored by satellite altimetry since 1992, there are limited observations of vertical land motion. Vertical land motion is generally modelled as a linear proce...

Tides in the Arctic Ocean affect ocean circulation and mixing, and sea ice dynamics and thermodynamics. However, there is a limited network of available in situ tidal coefficient data for understanding tidal variability in the Arctic Ocean; e.g., the global TICON-3 database contains only 111 sites above 60°N and 21 above 70°N. At the same time, the...

For more than three decades, satellite altimetry has provided valuable measurement data for the monitoring and analysis of ocean and inland water surfaces. Since 1992, there have always been at least two simultaneous missions providing continuous measurement data, starting with TOPEX/Poseidon and ERS‐1 in the early 1990s and continuing with about 1...

Coastal subsidence can significantly increase rates of relative sea level change over and above climate-related changes, and has been reported to be particularly large in densely populated regions. However, due to the small scale variability of vertical land motion (VLM) and the sparsity of VLM observations, there is currently still low confidence...

This study presents a comparative analysis of the coastal performances of Sentinel-6 and Jason-3 altimeters during their tandem phase, considering their different processing modes. We examine the measurements available in the standard geophysical data records (GDR) and also perform dedicated reprocessing using coastal retracking algorithms applied...

Tides in the Arctic Ocean affect ocean circulation and mixing, and sea ice dynamics and thermodynamics. However, there is a limited network of available in situ tidal coefficient data for understanding tidal variability in the Arctic Ocean; e.g., the global TICON-3 database contains only 111 sites above 60ºN and 21 above 70ºN. At the same time, the...

With the continued rise in global mean sea level, operational predictions of tidal height and total water levels have become crucial for accurate estimations and understanding of sea level processes. The Dutch Continental Shelf Model in Delft3D Flexible Mesh (DCSM-FM) is developed at Deltares to operationally estimate the total water levels to help...

The ionospheric information retrieved from the Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) system provides valuable and external data sources to examine the quality of existing Global Navigation Satellite System (GNSS) generated ionospheric models. The concept of DORIS differential Slant Total Electron Content (dSTEC)...

The global reach-scale “ICESat-2 River Surface Slope” (IRIS) dataset comprises average and extreme water surface slopes (WSS) derived from ICESat-2 observations between October 2018 and August 2022 as a supplement to 121,583 reaches from the “SWOT Mission River Database” (SWORD). To gain full advantage of ICESat-2’s unique measurement geometry with...

Estimating the three geophysical variables significant wave height (SWH), sea surface height, and wind speed from satellite altimetry continues to be challenging in the coastal zone because the received radar echoes exhibit significant interference from strongly reflective targets such as mud banks, sheltered bays, ships etc. Fully focused SAR (FF-...

Areas of thin sea ice in the polar regions not only are experiencing the highest rate of sea-ice production but also are, therefore, important hot spots for ocean ventilation as well as heat and moisture exchange between the ocean and the atmosphere. Through co-location of (1) an unsupervised waveform classification (UWC) approach applied to CryoSa...

Precise orbits of altimetry satellites are a prerequisite for the investigation of global, regional, and coastal sea levels together with their changes, since accurate satellite positions in the radial direction are required for the reliable determination of the water surface height (distance between the altimeter position in space and the water su...

Global ionospheric maps based on GNSS measurements are nowadays often used to correct satellite altimeter measurements when the instruments have only one frequency or measure over coasts and inland waters. If these corrections do not account for the free electron fraction over the altimeter satellites, this leads to systematic deviations in the ran...

The water surface slope (WSS) of rivers is essential for estimating flow velocity and discharge. It is also helpful as a correction applied to range measurements of satellite altimetry missions to derive water level time series at a virtual station. Using radar altimetry, WSS can only be roughly estimated and is limited to wide rivers because of it...

Precise orbits of altimetry satellites are a basis for sea surface height estimation, since they provide the reference for the measured distance from a satellite altimeter to a water surface. Various factors affect accuracy of orbits of these satellites, such as type and quality of observations used, proper corrections of measurements, proper model...

The TOPEX/Poseidon (T/P) altimetry mission with its main objectives to monitor variations of the global and regional sea level as well as ocean circulation is a milestone in Earth observation. The spacecraft was launched in 1992 and it is the predecessor mission of the Jason series and Sentinel-6A. For laser ranging measurements from the Earth to t...

One of the major sources of uncertainty affecting vertical land motion (VLM) estimations are discontinuities and trend changes. Trend changes are most commonly caused by seismic deformation, but can also stem from long-term (decadal to multidecadal) surface loading changes or from local origins. Although these issues have been extensively addressed...

The sea level retrievals from the latest generation of radar altimeters (the SAR altimeters) are still challenging in the coastal zone and areas covered by sea ice and require a dedicated fitting (retracking) strategy for the waveforms. In the framework of the European Space Agency’s Baltic + Sea Level (ESA Baltic SEAL) project, an empirical retrac...

Vertical land movements can cause regional relative sea level changes to differ substantially from climate-driven absolute (geocentric) sea level changes, on the order of mm to cm per year. While absolute sea level has been accurately monitored by satellite altimetry since 1992, vertical land motion is observed only point-wise or modelled following...

One of the major sources of uncertainty affecting vertical land motion (VLM) estimations are discontinuities and trend changes. Trend changes are most commonly caused by seismic deformation, but can also stem from long-term (decadal to multidecadal) surface loading changes or from local origins. Although these issues have been extensively addressed...

Areas of thin sea ice in the polar regions are not only experiencing the highest rate of sea-ice production but are, therefore, also important hot spots for ocean ventilation as well as heat and moisture exchange between the ocean and the atmosphere. Through co-location of (1) Moderate Resolution Imaging Spectroradiometer (MODIS) derived thin-ice t...

We employ the barotropic, data-unconstrained ocean tide model TiME to derive an atlas for degree-3 tidal constituents including monthly to terdiurnal tidal species. The model is optimized with respect to the tide gauge data set TICON-td that is extended to include the respective tidal constituents of diurnal and higher frequencies. The tide gauge v...

Atmospheric delay corrections for satellite altimetry measurements are essential for deriving highly accurate sea surface heights and reliable global mean sea level (GMSL) trend estimates. A commonly used method to correct for ionospheric path delays are the usage of GNSS‐based Global Ionospheric Maps (GIM). The different orbit heights of GNSS and...

Satellite altimetry is a radar remote sensing technology for the precise observation of the ocean surface and its changes over time. Its measurements allow the determination of geometric and physical parameters such as sea level, significant wave height or wind speed. This work presents a novel coastal retracking algorithm for SAR altimetry to esti...

Satellite altimetry observations have provided a significant contribution to the understanding of global sea surface processes, particularly allowing for advances in the accuracy of ocean tide estimations. Currently, almost three decades of satellite altimetry are available which can be used to improve the understanding of ocean tides by allowing f...

EOT20 is the latest in a series of empirical ocean tide (EOT) models derived using residual tidal analysis of multi-mission satellite altimetry at DGFI-TUM. The amplitudes and phases of 17 tidal constituents are provided on a global 0.125∘ grid based on empirical analysis of seven satellite altimetry missions and four extended missions. The EOT20 m...

Information on sea level and its temporal and spatial variability is of great importance for various scientific, societal, and economic issues. This article reports about a new sea level dataset for the North Sea (named North SEAL) of monthly sea level anomalies (SLAs), absolute sea level trends, and amplitudes of the mean annual sea level cycle ov...

This dataset contains gridded Sea Level Anomalies (SLA) for the North Sea, computed from multi-mission satellite altimetry at DGFI-TUM. SLA are provided in monthly temporal resolution between May-1995 and May-2019. The high-frequency cross-calibrated SLA observations are gridded by a least-squares approach on an unstructured triangular mesh with a...

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and mo...

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and mo...

Coastal studies of wave climate and evaluations of wave energy resources are mainly regional and based on the use of computationally very expensive models or a network of in-situ data. Considering the significant wave height, satellite radar altimetry provides an established global and relatively long-term source, whose coastal data are nevertheles...

The absolute sea level trend from May 1995 to May 2019 in the Baltic Sea is analyzed by means of a regional monthly gridded dataset based on a dedicated processing of satellite altimetry data. In addition, we evaluate the role of the North Atlantic Oscillation and the wind patterns in shaping differences in sea level trend and variability at a sub-...

Observations of changes in terrestrial water storage (TWS) obtained from the satellite mission GRACE (Gravity Recovery and Climate Experiment) have frequently been used for water cycle studies and for the improvement of hydrological models by means of calibration and data assimilation. However, due to a low spatial resolution of the gravity field m...

Precise orbits of altimetry satellites are a prerequisite for the investigation of global, regional, and coastal sea levels together with their changes, since accurate orbit information is required for the reliable determination of the water surface height (distance between the altimeter position in space and the water surface). Orbits of altimetry...

Information on sea level and its temporal and spatial variability is of great importance for various scientific, societal and economic issues. This article reports about a new sea level dataset for the North Sea (named NorthSEAL) of monthly sea level anomalies (SLA), absolute sea level trends and sea level mean annual amplitudes over the period 199...

EOT20 is the latest in a series of empirical ocean tide (EOT) models derived using residual tidal analysis of multi-mission satellite altimetry at DGFI-TUM. The amplitudes and phases of seventeen tidal constituents are provided on a global 0.125-degree grid based on empirical analysis of seven satellite altimetry missions and four extended missions...

Vertical land motion (VLM) at the coast is a substantial contributor to relative sea level change. In this work, we present a refined method for its determination, which is based on the combination of absolute satellite altimetry (SAT) sea level measurements and relative sea level changes recorded by tide gauges (TGs). These measurements complement...

Observations of changes in terrestrial water storage obtained from the satellite mission GRACE (Gravity Recovery and Climate Experiment) have frequently been used for water cycle studies and for the improvement of hydrological models by means of calibration and data assimilation. However, due to a low spatial resolution of the gravity field models...

Remote sensing data are essential for monitoring the Earth's surface waters, especially since the amount of publicly available in-situ data is declining. Satellite altimetry provides valuable information on the water levels and variations of lakes, reservoirs and rivers. In combination with satellite imagery, the derived time series allow the monit...

Despite increasing interest in monitoring the global water cycle, the availability of in situ gauging and discharge time series is decreasing. However, this lack of ground data can partly be compensated for by using remote sensing techniques to observe river stages and discharge. In this paper, a new approach for estimating discharge by combining w...

Abstract. Vertical land motion (VLM) at the coast is a substantial contributor to relative sea level change. In this work, we present a refined method for its determination, which is based on the combination of absolute satellite alimetry (SAT) sea level measurements and relative sea level changes recorded by tide gauges (TG). These measurements co...

In this study, a new approach for estimating volume variations of lakes and reservoirs using water levels from satellite altimetry and surface areas from optical imagery is presented. Both input data sets, namely water level time series and surface area time series, are provided by the Database of Hydrological Time Series of Inland Waters (DAHITI),...

For low Earth orbiting satellites, non-gravitational forces cause one of the largest perturbing accelerations. During a precise orbit determination (POD), the accurate modeling of the satellite-body attitude and solar panel orientation is important since the satellite’s effective cross-sectional area is directly related to the perturbing accelerati...

This special issue compiles studies from different disciplines presenting recent advances in the field of radar and laser altimetry including new and future altimetry missions and their applications. It comprises eight research papers as well as one review paper, and covers method development as well as applications, which target diverse Earth syst...

A deeper knowledge about geostrophic ocean surface currents in the northern Nordic Seas supports the understanding of ocean dynamics in an area affected by sea ice and rapidly changing environmental conditions. Monitoring these areas by satellite altimetry results in a fragmented and irregularly distributed data sampling and prevents the computatio...

The data set contains combined Dynamic Ocean Topography (DOT) and geostrophic velocity components for the northern Nordic Seas between 1995 and 2012. It was produced in the frame of the DFG project NEG-OCEAN: Variations in ocean currents, sea-ice concentration, and sea surface temperature along the North-East coast of Greenland. The data is provide...

For non-spherical satellites, the precise knowledge on satellite attitude is important for precise modeling of non-gravitational forces acting on a satellite. Moreover, the satellite attitude is necessary for the correct definition of the phase centers of the mounted SLR, DORIS and GPS measurement devices in space. The phase center corrections are...

The updated Empirical Ocean Tide model (EOT19p) currently available on limited regions is presented in this paper. Its implementation is focused on improving the accuracy of tidal estimation at the coast. EOT19p is derived using circa 27 years of coast-dedicated altimetric data and the FES2014 tide model, and it is based on a multi-mission, weighte...