Inst. Geodäsie und Geoinformationstechnik

77 Items

Recent Submissions
Remote sensing ionospheric variations due to total solar eclipse, using GNSS observations

Alizadeh, Mohamad Mahdi ; Schuh, Harald ; Zare, Saeed ; Sobhkhiz-Miandehi, Sahar ; Tsai, Lung-Chih (2019-10-01)

For years great interest has been taken in the effects of physical phenomena on ionosphere structure. A total solar eclipse was visible in North America on August 21st, 2017. This event offered a great opportunity for remote sensing the ionospheric behavior under the eclipse condition. In this study we investigated the effects of total solar eclipse on variations of Total Electron Content (TEC)...

Temperatures near the lunar poles and their correlation with hydrogen predicted by LEND

Gläser, Philipp (2020)

We modeled temperatures for eight selected regions at the lunar poles for a total of 30 layers, from the surface down to two meters depth. For each region and depth layer we determined where water ice could be stable, i.e. where temperature is below 110 K. The areas of potential water ice were then compared to hydrogen maps derived from data of the Lunar Exploration Neutron Detector (LEND). The...

Variance Reduction of Sequential Monte Carlo Approach for GNSS Phase Bias Estimation

Tian, Yumiao ; Ge, Maorong ; Neitzel, Frank (2020-04-03)

Global navigation satellite systems (GNSS) are an important tool for positioning, navigation, and timing (PNT) services. The fast and high-precision GNSS data processing relies on reliable integer ambiguity fixing, whose performance depends on phase bias estimation. However, the mathematic model of GNSS phase bias estimation encounters the rank-deficiency problem, making bias estimation a diffi...

Automatic Calibration of Process Noise Matrix and Measurement Noise Covariance for Multi-GNSS Precise Point Positioning

Zhang, Xinggang ; Li, Pan ; Tu, Rui ; Lu, Xiaochun ; Ge, Maorong ; Schuh, Harald (2020-04-02)

The Expectation-Maximization algorithm is adapted to the extended Kalman filter to multiple GNSS Precise Point Positioning (PPP), named EM-PPP. EM-PPP considers better the compatibility of multiple GNSS data processing and characteristics of receiver motion, targeting to calibrate the process noise matrix Qt and observation matrix Rt, having influence on PPP convergence time and precision, with...

Evaluation of E Layer Dominated Ionosphere Events Using COSMIC/FORMOSAT-3 and CHAMP Ionospheric Radio Occultation Data

Kamal, Sumon ; Jakowski, Norbert ; Hoque, Mohammed M. ; Wickert, Jens (2020-01-20)

At certain geographic locations, especially in the polar regions, the ionization of the ionospheric E layer can dominate over that of the F2 layer. The associated electron density profiles show their ionization maximum at E layer heights between 80 and 150 km above the Earth’s surface. This phenomenon is called the “E layer dominated ionosphere” (ELDI). In this paper we systematically investiga...

Drift of the Earth’s Principal Axes of Inertia from GRACE and Satellite Laser Ranging Data

Ferrándiz, José M. ; Modiri, Sadegh ; Belda, Santiago ; Barkin, Mikhail ; Bloßfeld, Mathis ; Heinkelmann, Robert ; Schuh, Harald (2020-01-18)

The location of the Earth’s principal axes of inertia is a foundation for all the theories and solutions of its rotation, and thus has a broad effect on many fields, including astronomy, geodesy, and satellite-based positioning and navigation systems. That location is determined by the second-degree Stokes coefficients of the geopotential. Accurate solutions for those coefficients were limited ...

On the eve of the 100th anniversary of IAU Commission 19/A2 “Rotation of the Earth”

Malkin, Zinovy ; Gross, Richard ; McCarthy, Dennis ; Brzeziński, Aleksander ; Capitaine, Nicole ; Dehant, Véronique ; Huang, Chengli ; Schuh, Harald ; Vondrák, Jan ; Yatskiv, Yaroslav (2018-12)

IAU Commission 19 began in 1919 with the birth of the IAU at the Brussels Conference, where Standing Committee 19 on Latitude Variations was established as one of 32 standing committees. At the first IAU General Assembly in 1922, Standing Committee 19 became Commission 19 “Variation of Latitude”. In the beginning, the main topic of the Commission was the investigation of polar motion. Later, it...

First evidence of mesoscale ocean eddies signature in GNSS reflectometry measurements

Hoseini, Mostafa ; Asgarimehr, Milad ; Zavorotny, Valery ; Nahavandchi, Hossein ; Ruf, Chris ; Wickert, Jens (2020-02-06)

Feasibility of sensing mesoscale ocean eddies using spaceborne Global Navigation Satellite Systems-Reflectometry (GNSS-R) measurements is demonstrated for the first time. Measurements of Cyclone GNSS (CYGNSS) satellite missions over the eddies, documented in the Aviso eddy trajectory atlas, are studied. The investigation reports on the evidence of normalized bistatic radar cross section ( σ0 ) ...

New nonlinear adjustment approaches for applications in geodesy and related fields

Malissiovas, Georgios (2019)

This dissertation deals with a class of nonlinear adjustment problems that has a direct least squares solution for certain weighting cases. In the literature of mathematical statistics these problems are expressed in a nonlinear model called Errors-In-Variables (EIV) and their solution became popular as total least squares (TLS). The TLS solution is direct and involves the use of singular value...

Multi-GNSS precise position, velocity, and acceleration determination for airborne gravimetry over Antarctica

Min, Li (2020)

The precise knowledge of aircraft position, velocity, and acceleration is a mandatory prerequisite for airborne gravimetry. For the determination of these quantities the Global Navigation Satellite System (GNSS) plays an important role. However, kinematic positioning over Antarctica is a challenging task which is different from positioning in low-latitude regions. The main reason is the sparse ...

Retrieving Precipitable Water Vapor From Shipborne Multi‐GNSS Observations

Wang, Jungang ; Wu, Zhilu ; Semmling, Maximilian ; Zus, Florian ; Gerland, Sebastian ; Ramatschi, Markus ; Ge, Maorong ; Wickert, Jens ; Schuh, Harald (2019-05-15)

Precipitable water vapor (PWV) is an important parameter for climate research and a crucial factor to achieve high accuracy in satellite geodesy and satellite altimetry. Currently Global Navigation Satellite System (GNSS) PWV retrieval using static Precise Point Positioning is limited to ground stations. We demonstrated the PWV retrieval using kinematic Precise Point Positioning method with shi...

Coordinates and maps of the Apollo 17 landing site

Haase, Isabel ; Wählisch, Marita ; Gläser, Philipp ; Oberst, Jürgen ; Robinson, Mark S. (2018-12-07)

We carried out an extensive cartographic analysis of the Apollo 17 landing site and determined and mapped positions of the astronauts, their equipment, and lunar landmarks with accuracies of better than ±1 m in most cases. To determine coordinates in a lunar body‐fixed coordinate frame, we applied least squares (2‐D) network adjustments to angular measurements made in astronaut imagery (Hasselb...

Can GNSS reflectometry detect precipitation over oceans?

Asgarimehr, Milad ; Zavorotny, Valery ; Wickert, Jens ; Reich, Sebastian (2018-11-06)

For the first time, a rain signature in Global Navigation Satellite System Reflectometry (GNSS‐R) observations is demonstrated. Based on the argument that the forward quasi‐specular scattering relies upon surface gravity waves with lengths larger than several wavelengths of the reflected signal, a commonly made conclusion is that the scatterometric GNSS‐R measurements are not sensitive to the s...

Estimating integrated water vapor trends from VLBI, GPS,and numerical weather models: sensitivity totropospheric parameterization

Balidakis, Kyriakos ; Nilsson, Tobias ; Zus, Florian ; Glaser, Susanne ; Heinkelmann, Robert ; Deng, Zhiguo ; Schuh, Harald (2018-06-20)

In this study, we estimate integrated water vapor (IWV) trends from very long baseline interferometry (VLBI) and global navigation satellite systems (GNSS) data analysis, as well as from numerical weather models (NWMs). We study the impact of modeling and parameterization of the tropospheric delay from VLBI on IWV trends. We address the impact of the meteorological data source utilized to model...

A Decentralized Processing Schema for Efficient and Robust Real-time Multi-GNSS Satellite Clock Estimation

Jiang, Xinyuan ; Gu, Shengfeng ; Li, Pan ; Ge, Maorong ; Schuh, Harald (2019-11-05)

Real-time multi-GNSS precise point positioning (PPP) requires the support of high-rate satellite clock corrections. Due to the large number of ambiguity parameters, it is difficult to update clocks at high frequency in real-time for a large reference network. With the increasing number of satellites of multi-GNSS constellations and the number of stations, real-time high-rate clock estimation be...

The GFZ GRACE RL06 Monthly Gravity Field Time Series: Processing Details and Quality Assessment

Dahle, Christoph ; Murböck, Michael ; Flechtner, Frank ; Dobslaw, Henryk ; Michalak, Grzegorz ; Neumayer, Karl Hans ; Abrykosov, Oleh ; Reinhold, Anton ; König, Rolf ; Sulzbach, Roman ; Förste, Christoph (2019-09-11)

Time-variable gravity field models derived from observations of the Gravity Recovery and Climate Experiment (GRACE) mission, whose science operations phase ended in June 2017 after more than 15 years, enabled a multitude of studies of Earth’s surface mass transport processes and climate change. The German Research Centre for Geosciences (GFZ), routinely processing such monthly gravity fields as...

Mitigation of Unmodeled Error to Improve the Accuracy of Multi-GNSS PPP for Crustal Deformation Monitoring

Zheng, Kai ; Zhang, Xiaohong ; Li, Xingxing ; Li, Pan ; Chang, Xiao ; Sang, Jizhang ; Ge, Maorong ; Schuh, Harald (2019-09-25)

High-rate multi-constellation global navigation satellite system (GNSS) precise point positioning (PPP) has been recognized as an efficient and reliable technique for large earthquake monitoring. However, the displacements derived from PPP are often overwhelmed by the centimeter-level noise, therefore they are usually unable to detect slight deformations which could provide new findings for geo...

On the development and impact of propagation delay and geophysical loading on space geodetic technique data analysis

Balidakis, Kyriakos (2019)

This study contributes to the effort of space geodesy to reach the 1 mm accuracy level on a global scale. This stringent requirement is vital to realize a global reference system upon which phenomena such as sea-level rise can be reliably monitored. The study deals with two interrelated challenges: modeling geophysical loads imposed on the crust of the Earth and quantifying the atmospheric prop...

Observations of meteors in the Earth’s atmosphere: Reducing data from dedicated double-station wide-angle cameras

Margonis, Anastasios ; Christou, Apostolos ; Oberst, Jürgen (2018-10-17)

Meteoroids entering the Earth’s atmosphere can be observed as meteors, thereby providing useful information on their formation and hence on their parent bodies. We developed a data reduction software package for double station meteor data from the SPOSH camera, which includes event detection, image geometric and radiometric calibration, radiant and speed estimates, trajectory and orbit determin...

Characterisation of the Perseid meteoroid stream through SPOSH observations between 2010–2016

Margonis, Anastasios ; Christou, Apostolos ; Oberst, Jürgen (2019-06-07)

We have characterised the Perseid meteoroid stream from data acquired in a series of observing campaigns between 2010 and 2016. The data presented in this work were obtained by the Smart Panoramic Optical Sensor Head (SPOSH), an all-sky camera system designed to image faint transient noctilucent phenomena on dark planetary hemispheres. For the data reduction, a sophisticated software package wa...