Denise Dettmering

Denise Dettmering
Technische Universität München | TUM · Deutsches Geodätisches Forschungsinstitut

Dr.-Ing.

About

139
Publications
30,473
Reads
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1,589
Citations
Additional affiliations
July 2007 - March 2015
Deutsches Geodätisches Forschungsinstitut (DGFI)
Position
  • Research Associate

Publications

Publications (139)
Preprint
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...
Article
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...
Article
Full-text available
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...
Article
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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-...
Article
Full-text available
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...
Preprint
Full-text available
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...
Preprint
Full-text available
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...
Article
Full-text available
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...
Preprint
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Preprint
Full-text available
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...
Article
Full-text available
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),...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Conference Paper
Full-text available
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...
Article
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...
Article
Full-text available
The TICON (TIdal CONstants) dataset contains harmonic constants of 40 tidal constituents computed for 1,145 tide gauges distributed globally. The tidal estimations are based on publicly available sea level records of the second version of the Global Extreme Sea Level Analysis (GESLA) project and were derived through a least squares‐based harmonic a...
Article
Full-text available
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...
Article
Full-text available
In this study, a new approach for the automated extraction of high-resolution time-variable water surfaces is presented. For that purpose, optical images from Landsat and Sentinel-2 are used between January 1984 and June 2018. The first part of this new approach is the extraction of land-water masks by combining five water indexes and using an auto...
Article
Full-text available
Single-mission altimetric water level observations of rivers are spatially and temporally limited, and thus they are often unable to quantify the full extent of extreme flood events. Moreover, only missions with a short-repeat orbit, such as Envisat, Jason-2, or SARAL, could provide meaningful time series of water level variations directly. However...
Article
Full-text available
The dynamic ocean topography (DOT) of the polar seas can be described by satellite altimetry sea surface height observations combined with geoid information as well as by ocean models. The altimetry observations are characterized by an irregular sampling and seasonal sea ice coverage complicating reliable DOT estimations. Models display various spa...
Article
Full-text available
A terrestrial reference frame (TRF) is a basis for precise orbit determination of Earth-orbiting satellites, since it defines positions and velocities of stations, the tracking data of which are used to derive satellite positions. In this paper, we investigate the impact of the International Terrestrial Reference Frame realization ITRF2014, as comp...
Chapter
The inter-mission cross-calibration is a basic prerequisite for long-term sea level change studies on all spatial scales. Especially, for climate studies the consistent combination of successive missions is essential. This study uses a global multi-mission crossover analysis in order to investigate the performance of the Copernicus Sentinel-3A alti...
Article
Full-text available
The dynamic ocean topography (DOT) in the polar seas can be described by satellite altimetry sea surface height observations combined with geoid information and by ocean models. The altimetry observations are characterized by an irregular sampling and seasonal sea-ice coverage complicating reliable DOT estimations. Models display various spatio-tem...
Conference Paper
Full-text available
Starting with ERS-1 and TOPEX/Poseidon in 1992 the altimeter record has reached already 25 years. Since orbits of altimeter satellites are a prerequisite for sea level investigations and since any radial error directly maps in sea level derived in satellite altimetry, long-term stability of orbits of altimeter satellites is very important, especial...
Article
Full-text available
In polar regions, sea-ice hinders the precise observation of Sea Surface Heights (SSH) by satellite altimetry. In order to derive reliable heights for the openings within the ice, two steps have to be fulfilled: (1) the correct identification of water (e.g., in leads or polynias), a process known as lead classification; and (2) dedicated retracking...
Article
Full-text available
A terrestrial reference frame (TRF) is a basis for precise orbit determination of Earth orbiting satellites, since it defines positions and velocities of stations tracking data of which is used to derive satellite positions. In this paper, we investigate the impact of the International Terrestrial Reference Frame realization ITRF2014, as compared t...
Conference Paper
Full-text available
An International Terrestrial Reference System realization is a basis for precise monitoring global change phenomena, such as tectonic motion and deformations, postglacial rebound, global and regional sea level change, Earth’s rotation, precise positioning applications on and near the Earth’s surface, precise orbit determination (POD) and other appl...
Conference Paper
Full-text available
The advantages of reprocessing the data from pulse-limited altimetry with the Adaptive Leading Edge Subwaveform Retracking (ALES) algorithm have been already demonstrated at the coast. We demonstrate in this talk that the same strategy improves the precision of satellite altimetry in the global ocean, presenting the new global ALES dataset, which i...
Preprint
Single-mission altimetric water level observations of rivers are spatially and temporally limited, and thus they are often unable to quantify the full extent of extreme flood events. Moreover, only missions with a short-repeat orbit, such as Envisat, Jason-2, or SARAL, could observe time series of water level variations directly. However, long or n...
Article
Full-text available
Since the launch of the first altimetry satellites, ocean tide models have been improved dramatically for deep and shallow waters. However, issues are still found for areas of great interest for climate change investigations: the coastal regions. The purpose of this study is to analyze the influence of the ALES coastal retracker on tide modeling in...
Presentation
Full-text available
The research conducted within the International Association of Geodesy (IAG) Real Time Ionosphere Monitoring Working Group (RTIM-WG), which is part of IAG’s Sub-Commission 4.3 “Atmosphere Remote Sensing”, will be presented. In particular, we will focus on the comparison and validation of real-time and near real-time VTEC Global Ionopheric Maps (GIM...
Article
Full-text available
Water level from sea ice-covered oceans is particularly challenging to retrieve with satellite radar altimeters due to the different shapes assumed by the returned signal compared with the standard open ocean waveforms. Valid measurements are scarce in large areas of the Arctic and Antarctic Oceans, because sea level can only be estimated in the op...
Article
In 2016, three new realizations of the International Terrestrial Reference System (ITRS), namely, DTRF2014, ITRF2014, and JTRF2014, have been released. In this paper, we evaluate these ITRS realizations for precise orbit determination of ten high and low Earth orbiting geodetic satellites using satellite laser ranging (SLR) observations. We show th...
Article
Full-text available
In this study we use CryoSat-2 SAR (delay-Doppler synthetic-aperture radar) data in the Mekong River Basin to estimate water levels. Compared to classical pulse limited radar altimetry, medium- and small-sized inland waters can be observed with CryoSat-2 SAR data with a higher accuracy due to the smaller along track footprint. However, even with th...
Conference Paper
Full-text available
A high accuracy, consistent and long-term stable realization of the International Terrestrial Reference System (ITRS) is a basis for the investigations of the global and regional mean sea level changes, dynamics of the points on the Earth's surface, solid Earth deformations, tectonic motion, Earth's rotation, post-glacial rebound, precise orbit det...
Article
In the Arctic and Antarctic Ocean, where part of the sea surface is seasonally or continuously covered by sea ice, the sea level monitoring from satellite altimetry relies on the localisation of open water areas, especially on the detection of leads: long and narrow fractures in the sea ice, which dominate the radar echoes even if hundreds of meter...
Article
Full-text available
In this study we use CryoSat-2 SAR (Delay-Doppler Synthetic Aperture Radar) data over the Mekong River Basin to estimate water levels. Smaller inland waters can be observed with CryoSat-2 data with a higher accuracy compared to the classical radar altimeters due to the increased along track resolution of SAR and the smaller footprint. However, even...
Article
Full-text available
Open water areas surrounded by sea ice significantly influence the ocean-ice-atmosphere interaction and contribute to Arctic climate change. Satellite altimetry can detect these ice openings and enables one to estimate sea surface heights and further altimetry data derived products. This study introduces an innovative, unsupervised classification a...
Conference Paper
Full-text available
Recently, three new realizations of the International Terrestrial Reference System (ITRS) have been released. They are DTRF2014 developed by the International Earth Rotation and Reference Systems Service (IERS) ITRS Combination Centre at Deutsches Geodätisches Forschungsinstitut of the Technische Universität München, ITRF2014 elaborated at the IERS...
Article
New, precise, consistent orbits (VER11) of altimetry satellites ERS-1, ERS-2, TOPEX/Poseidon, Envisat, Jason-1, and Jason-2 have been recently derived at the GFZ German Research Centre for Geosciences in the extended ITRF2008 terrestrial reference frame using improved models and covering the time span 1991-2015. These orbits show improved quality,...
Data
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