Articles | Volume 37, issue 4
https://doi.org/10.5194/angeo-37-699-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/angeo-37-699-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
High-resolution vertical total electron content maps based on multi-scale B-spline representations
Deutsches Geodätisches Forschungsinstitut der Technischen Universität München, Arcisstraße 21, 80333 Munich, Germany
Michael Schmidt
Deutsches Geodätisches Forschungsinstitut der Technischen Universität München, Arcisstraße 21, 80333 Munich, Germany
Eren Erdogan
Deutsches Geodätisches Forschungsinstitut der Technischen Universität München, Arcisstraße 21, 80333 Munich, Germany
Barbara Görres
Bundeswehr GeoInformation Centre (BGIC), Euskirchen, Germany
Florian Seitz
Deutsches Geodätisches Forschungsinstitut der Technischen Universität München, Arcisstraße 21, 80333 Munich, Germany
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Michael G. Hart-Davis, Gaia Piccioni, Denise Dettmering, Christian Schwatke, Marcello Passaro, and Florian Seitz
Earth Syst. Sci. Data, 13, 3869–3884, https://doi.org/10.5194/essd-13-3869-2021, https://doi.org/10.5194/essd-13-3869-2021, 2021
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Ocean tides are an extremely important process for a variety of oceanographic applications, particularly in understanding coastal sea-level rise. Tidal signals influence satellite altimetry estimations of the sea surface, which has resulted in the development of ocean tide models to account for such signals. The EOT20 ocean tide model has been developed at DGFI-TUM using residual analysis of satellite altimetry, with the focus on improving the estimation of ocean tides in the coastal region.
Denise Dettmering, Felix L. Müller, Julius Oelsmann, Marcello Passaro, Christian Schwatke, Marco Restano, Jérôme Benveniste, and Florian Seitz
Earth Syst. Sci. Data, 13, 3733–3753, https://doi.org/10.5194/essd-13-3733-2021, https://doi.org/10.5194/essd-13-3733-2021, 2021
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In this study, a new gridded altimetry-based regional sea level dataset for the North Sea is presented, named North SEAL. It is based on long-term multi-mission cross-calibrated altimetry data consistently preprocessed with coastal dedicated algorithms. On a 6–8 km wide triangular mesh, North SEAL provides time series of monthly sea level anomalies as well as sea level trends and amplitudes of the mean annual sea level cycle for the period 1995–2019 for various applications.
Julius Oelsmann, Marcello Passaro, Denise Dettmering, Christian Schwatke, Laura Sánchez, and Florian Seitz
Ocean Sci., 17, 35–57, https://doi.org/10.5194/os-17-35-2021, https://doi.org/10.5194/os-17-35-2021, 2021
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Vertical land motion (VLM) significantly contributes to relative sea level change. Here, we improve the accuracy and precision of VLM estimates, which are based on the difference of altimetry tide gauge observations. Advanced coastal altimetry and an improved coupling procedure of along-track altimetry data and high-frequency tide gauge observations are key factors for a greater comparability of altimetry and tide gauges in the coastal zone and thus for more reliable VLM estimates.
Tatjana Gerzen, David Minkwitz, Michael Schmidt, and Eren Erdogan
Ann. Geophys., 38, 1171–1189, https://doi.org/10.5194/angeo-38-1171-2020, https://doi.org/10.5194/angeo-38-1171-2020, 2020
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We focus on reconstructing the topside ionosphere and plasmasphere and assimilating the space-based Global Navigation Satellite System slant total electron content (STEC) measurements with an ensemble Kalman filter (EnKF). We present methods for realizing the propagation step without a physical model. We investigate the capability of our estimations to reconstruct independent STEC and electron density measurements. We compare the EnKF approach with SMART+ and the 3D ionosphere model NeQuick.
Felix L. Müller, Denise Dettmering, Claudia Wekerle, Christian Schwatke, Marcello Passaro, Wolfgang Bosch, and Florian Seitz
Earth Syst. Sci. Data, 11, 1765–1781, https://doi.org/10.5194/essd-11-1765-2019, https://doi.org/10.5194/essd-11-1765-2019, 2019
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Polar regions by satellite-altimetry-derived geostrophic currents (GCs) suffer from irregular and sparse data coverage. Therefore, a new dataset is presented, combining along-track derived dynamic ocean topography (DOT) heights with simulated differential water heights. For this purpose, a combination method, based on principal component analysis, is used. The results are combined with spatio-temporally consistent DOT and derived GC representations on unstructured, triangular formulated grids.
Alexander Kehm, Mathis Bloßfeld, Peter König, and Florian Seitz
Adv. Geosci., 50, 17–25, https://doi.org/10.5194/adgeo-50-17-2019, https://doi.org/10.5194/adgeo-50-17-2019, 2019
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Satellite Laser Ranging is one of the four fundamental geodetic space techniques for the accurate determination of geodetic key parameters related to the Earth’s geometry, rotation and gravity field. As the current global SLR station distribution is quite inhomogeneous, a simulation study has been performed in order to determine locations on Earth where additional SLR sites will be most valuable for an improvement of the results, the Antarctic region having been identified as a first priority.
Qing Liu, Michael Schmidt, Roland Pail, and Martin Willberg
Solid Earth Discuss., https://doi.org/10.5194/se-2019-60, https://doi.org/10.5194/se-2019-60, 2019
Preprint withdrawn
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Regularization is indispensable in regional gravity field modelling. In this paper, we propose two new approaches for the regularization parameter determination, which combine the L-curve method and variance component estimation (VCE). The performance of each method is studied for combining heterogeneous observations using spherical radial basis functions. The results show that our newly proposed methods are decent and stable for regularization parameter determination.
Felix L. Müller, Claudia Wekerle, Denise Dettmering, Marcello Passaro, Wolfgang Bosch, and Florian Seitz
The Cryosphere, 13, 611–626, https://doi.org/10.5194/tc-13-611-2019, https://doi.org/10.5194/tc-13-611-2019, 2019
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Knowledge of the dynamic ocean topography (DOT) enables studying changes of ocean surface currents. The DOT can be derived by satellite altimetry measurements or by models. However, in polar regions, altimetry-derived sea surface heights are affected by sea ice. Model representations are consistent but impacted by the underlying functional backgrounds and forcing models. The present study compares results from both data sources in order to investigate the potential for a combination of the two.
Laura Sánchez, Christof Völksen, Alexandr Sokolov, Herbert Arenz, and Florian Seitz
Earth Syst. Sci. Data, 10, 1503–1526, https://doi.org/10.5194/essd-10-1503-2018, https://doi.org/10.5194/essd-10-1503-2018, 2018
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We provide a surface-kinematics model for the Alpine region based on high-level data analysis of 300 geodetic stations continuously operating over 12.4 years. This model includes a deformation model, a continuous velocity field, and a strain field consistently assessed for the entire Alpine mountain belt. Horizontal and vertical motion patterns are clearly identified and supported by uncertainties better than ±0.2 mm a−1 and ±0.3 mm a−1 in the horizontal and vertical components, respectively.
Chao Xiong, Hermann Lühr, Michael Schmidt, Mathis Bloßfeld, and Sergei Rudenko
Ann. Geophys., 36, 1141–1152, https://doi.org/10.5194/angeo-36-1141-2018, https://doi.org/10.5194/angeo-36-1141-2018, 2018
Eva Boergens, Karina Nielsen, Ole B. Andersen, Denise Dettmering, and Florian Seitz
Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2017-217, https://doi.org/10.5194/hess-2017-217, 2017
Revised manuscript not accepted
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The water levels of the Mekong River are observed with the SAR altimeter measurements of CryoSat-2. Even small rivers in the river system with a width of 50 m can be observed due to the higher resolution of the SAR measurements. To identify the rivers regardless of a land-water-mask we employ an unsupervised classification on features derived from the SAR measurements. The river water levels are validated and compared to gauge and Envisat data which shows the good performance of the SAR data.
Eren Erdogan, Michael Schmidt, Florian Seitz, and Murat Durmaz
Ann. Geophys., 35, 263–277, https://doi.org/10.5194/angeo-35-263-2017, https://doi.org/10.5194/angeo-35-263-2017, 2017
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Although the number of terrestrial GNSS receivers is rapidly growing, the rather unevenly distributed observations do not allow the generation of high-resolution global ionosphere products. With the regionally enormous increase in GNSS data, the demands on near real-time products are growing very fast. Thus, a procedure for estimating the vertical total electron content based on B-spline representations and Kalman filtering was developed and validated by self-consistency check and altimetry.
C. Schwatke, D. Dettmering, W. Bosch, and F. Seitz
Hydrol. Earth Syst. Sci., 19, 4345–4364, https://doi.org/10.5194/hess-19-4345-2015, https://doi.org/10.5194/hess-19-4345-2015, 2015
M. Limberger, W. Liang, M. Schmidt, D. Dettmering, M. Hernández-Pajares, and U. Hugentobler
Ann. Geophys., 32, 1533–1545, https://doi.org/10.5194/angeo-32-1533-2014, https://doi.org/10.5194/angeo-32-1533-2014, 2014
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The determination of ionospheric key quantities such as the maximum electron density of the F2 layer, the corresponding F2 peak height and the F2 scale height are of high relevance in 4-D ionosphere modeling to provide information on the vertical structure of the electron density distribution. This paper discusses mathematical correlations between these parameters as derived from FORMOSAT-3/COSMIC radio occultations and regionally parameterized by means of polynomial B-splines.
M. Limberger, W. Liang, M. Schmidt, D. Dettmering, and U. Hugentobler
Ann. Geophys., 31, 2215–2227, https://doi.org/10.5194/angeo-31-2215-2013, https://doi.org/10.5194/angeo-31-2215-2013, 2013
Related subject area
Subject: Earth's ionosphere & aeronomy | Keywords: Modelling and forecasting
Modeling total electron content derived from radio occultation measurements by COSMIC satellites over the African region
Analysis of different propagation models for the estimation of the topside ionosphere and plasmasphere with an ensemble Kalman filter
The very low-frequency transmitter radio wave anomalies related to the 2010 Ms 7.1 Yushu earthquake observed by the DEMETER satellite and the possible mechanism
Comparison of quiet-time ionospheric total electron content from the IRI-2016 model and from gridded and station-level GPS observations
Performance of the IRI-2016 over Santa Maria, a Brazilian low-latitude station located in the central region of the South American Magnetic Anomaly (SAMA)
Validation and application of optimal ionospheric shell height model for single-site estimation of total electron content
Extending the coverage area of regional ionosphere maps using a support vector machine algorithm
Patrick Mungufeni, Sripathi Samireddipalle, Yenca Migoya-Orué, and Yong Ha Kim
Ann. Geophys., 38, 1203–1215, https://doi.org/10.5194/angeo-38-1203-2020, https://doi.org/10.5194/angeo-38-1203-2020, 2020
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This study developed a model of total electron content (TEC) over the African region. The TEC data were derived from radio occultation measurements done by the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites. Data during geomagnetically quiet time for the years 2008–2011 and 2013–2017 were binned according to local time, seasons, solar flux level, geographic longitude, and dip latitude. Cubic B splines were used to fit the data for the model.
Tatjana Gerzen, David Minkwitz, Michael Schmidt, and Eren Erdogan
Ann. Geophys., 38, 1171–1189, https://doi.org/10.5194/angeo-38-1171-2020, https://doi.org/10.5194/angeo-38-1171-2020, 2020
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We focus on reconstructing the topside ionosphere and plasmasphere and assimilating the space-based Global Navigation Satellite System slant total electron content (STEC) measurements with an ensemble Kalman filter (EnKF). We present methods for realizing the propagation step without a physical model. We investigate the capability of our estimations to reconstruct independent STEC and electron density measurements. We compare the EnKF approach with SMART+ and the 3D ionosphere model NeQuick.
Shufan Zhao, XuHui Shen, Zeren Zhima, and Chen Zhou
Ann. Geophys., 38, 969–981, https://doi.org/10.5194/angeo-38-969-2020, https://doi.org/10.5194/angeo-38-969-2020, 2020
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We use satellite data to analyze precursory anomalies of the western China Ms 7.1 Yushu earthquake by analyzing the signal-to-noise ratio (SNR) and using the full-wave model to illustrate a possible mechanism for how the anomalies occurred. The results show that very low-frequency (VLF) radio wave SNR in the ionosphere decreased before the Yushu earthquake. The full-wave simulation results confirm that electron density variation in the lower ionosphere will affect VLF radio signal SNR.
Gizaw Mengistu Tsidu and Mulugeta Melaku Zegeye
Ann. Geophys., 38, 725–748, https://doi.org/10.5194/angeo-38-725-2020, https://doi.org/10.5194/angeo-38-725-2020, 2020
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The performance of the IRI-2016 model in simulating GPS-TEC is assessed based on various statistical tools during two distinct solar activity periods. In particular, the categorical metrics used in the study to assess the performance of the empirical and climatological IRI-2016 model at the margins of the TEC distribution reveal remarkable model skill in simulating the observed tails of the TEC distribution, which is much better than accurately simulating the observed climatology as designed.
Juliano Moro, Jiyao Xu, Clezio Marcos Denardini, Laysa Cristina Araújo Resende, Régia Pereira Silva, Sony Su Chen, Giorgio Arlan da Silva Picanço, Liu Zhengkuan, Hui Li, Chunxiao Yan, Chi Wang, and Nelson Jorge Schuch
Ann. Geophys., 38, 457–466, https://doi.org/10.5194/angeo-38-457-2020, https://doi.org/10.5194/angeo-38-457-2020, 2020
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The monthly averages of the F2 critical frequency (foF2), its peak height (hmF2), and the E-region critical frequency (foE) acquired by the DPS4-D installed in Santa Maria, Brazil, is compared to the International Reference Ionosphere (IRI-2016) model predictions. It is important to test the performance of the IRI over Santa Maria because it is located in the SAMA, which is a region particularly important for high-frequency (HF) ground-to-satellite navigation signals.
Jiaqi Zhao and Chen Zhou
Ann. Geophys., 37, 263–271, https://doi.org/10.5194/angeo-37-263-2019, https://doi.org/10.5194/angeo-37-263-2019, 2019
Mingyu Kim and Jeongrae Kim
Ann. Geophys., 37, 77–87, https://doi.org/10.5194/angeo-37-77-2019, https://doi.org/10.5194/angeo-37-77-2019, 2019
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Spatial extrapolation of an ionosphere TEC map was carried out using a SVM learning algorithm. There has been much research on the temporal extrapolation or prediction of TEC time series, but the spatial extrapolation has rarely been attempted. Some researchers have performed simultaneous extrapolation both in time and in spatial domains, but this research covers the spatial extrapolation only by using an inner TEC map. This spatial TEC extrapolation can be useful for small countries.
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Short summary
This paper describes an approach to model VTEC solely from NRT GNSS observations by generating a multi-scale representation (MSR) based on B-splines. The unknown model parameters are estimated by means of a Kalman filter. A number of products are created which differ both in their spectral and temporal resolution. The validation studies show that the product with the highest resolution, based on NRT input data, is of higher accuracy than others used within the selected investigation time span.
This paper describes an approach to model VTEC solely from NRT GNSS observations by generating a...