Terrestrial Gravimetry

• Optical Clocks for Chronometric Levelling (CRC 1464, A04)

  We will realise the potential of chronometric levelling by demonstrating off-campus height measurements with the same or better resolution than geometric levelling and the Global Navigation Satellite System (GNSS)/geoid approach can presently achieve, in joint campaigns with project A05. This demonstration will be strengthened by the application of our measurement capabilities to geodetic problems of high relevance through cooperation with the TerraQ projects employing gravimetric and GNSS techniques to e.g. monitor water storage and other mass changes (projects Terrestrial Clock Networks: Fundamental Physics and Applications (C02), Modelling of Mass Variations Down to Small Scales by Quantum Sensor Fusion (C05), and Atmosphere-Ocean Background Modelling for Terrestrial Gravimetry (C06)).

  Led by: PD Dr. Christian Lisdat, Prof. Dr. Piet O. Schmidt, Dr.-Ing. Denker

  Team: Tim Lücke, Constantin Nauk

  Year: 2021

  Funding: DFG
• Validation of Quantum Gravimeter QG-1 for Hydrology (CRC 1464, C01)

  For the groundwater management in central Europe, ground-based gravimetry provides a unique potential to monitor temporal variations in the subsurface water content for local areas. The atomic Quantum Gravimeter-1 (QG-1) of Leibniz Universität Hannover (LUH) is in its final phase of development (A01) and will be ready for geodetic and gravimetric applications latest in 2021. The QG-1 capability will be demonstrated indoor and also in a field application as an advanced absolute gravimeter allowing effectively the surveying of gravity variations due to groundwater changes on the uncertainty level of 10 nm/s².

  Led by: Dr.-Ing. Heiner Denker, Dr.-Ing. Ludger Timmen

  Team: Dinesh Chebolu

  Year: 2021

  Funding: DFG
• Quantum Gravimetry (CRC 1464, A01)

  Within TerraQ we aim to establish atom-chip based Quantum Gravimetry with Bose-Einstein condensates (BECs) and explore its potential for mobile gravimetry. Deploying QG-1 (Quantum Gravimeter) with steadily increasing frequency and performance in measurement campaigns for C01, A05 and C05 will allow us to prove the in-field applicability of the associated methods and demonstrate an operation of QG-1 under varying, rough conditions.

  Led by: Dr. Waldemar Herr, Prof. Dr.-Ing. Jürgen Müller, Prof. Dr. Ernst Rasel

  Team: Nina Heine, Marat Musakaev

  Year: 2021

  Funding: DFG
• Atmosphere-Ocean Background Modelling for Terrestrial Gravimetry (CRC 1464, C06)

  We will focus on the development of global background models of atmosphere and ocean dynamics that are applicable to gravity records taken anywhere at the Earth’s surface. The background models will be split into deformation effects that also consider the laterally heterogeneous rheology of the Earth’s crust, regional-to-global attraction effects of both atmospheric and oceanic mass variability along the strategy outlined by, and the local effects from the direct vicinity of the sensor that are most sensible to the local topographic roughness and that might benefit most from a possible augmentation with barometric observations taken around the gravity sensor.

  Led by: Dr. Henryk Dobslaw, Dr.-Ing. Ludger Timmen

  Team: Dr. Kyriakos Balidakis

  Year: 2021

  Funding: DFG
• Gravimetric Tides and Gravity Currents in the North Sea

  The research group is investigating the gravity and deformation (tilt) effect caused by time variations of the mass distribution in the atmosphere and in the sea. It has to be distinguished between the direct Newtonian attraction effects and indirect loading effects. The latter part is accompanied by a vertical shift and a tilt of the sea floor as well as the land surface, especially along the coast or on islands, because of the elasticity of the solid Earth’s crust. Such a vertical ground displacement is associated with an absolute height change of the gravimeter w.r.t. the geocenter. The combined observation of gravity and tilt changes allows the separation of signals due to attraction and load deformation.

  Led by: Dr.-Ing. Ludger Timmen, Dr. Adelheid Weise

  Team: Dr.-Ing. Ludger Timmen, Dr. Adelheid Weise

  Year: 2018

  Funding: IfE, Germany’s Excellence Strategy – EXC-2123 “QuantumFrontiers”

  Duration: 2018-2021
• Gravimetry at Zugspitze and Wank Mountains (Bavarian Alps, Germany)

  The geodetic monitoring of variations caused by Alpine orogency and the diminishing permafrost are undertaken with gravimetric as well as geometric techniques. In addition to IfE (absolute and relative gravimetry, levelling), the Bavarian Academy of Sciences and Humanities (GNSS, levelling, relative gravimetry), the Institute of Astronomical and Physical Geodesy - Technical University of Munich (relative gravimetry) and the Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences (superconducting gravimetry, GNSS permanent geodynamic observatory on the Zugspitze) are involved in the cooperation.

  Led by: Dr.-Ing. Ludger Timmen

  Year: 2018

  Funding: IFE, Germany’s Excellence Strategy – EXC-2123 “QuantumFrontiers”, GFZ Potsdam, TU München, Bayerische Akademie der Wissenschaften
• Gravimetric reference network for a 10m atom interferometer

  The Very Long Baseline Atom Interferometer (VLBAI) at the Hannover Institute for Technology (HITec) is a physics instrument in which experiments on the interferometry of atoms can be carried out over a free-fall distance of about 10m. These experiments are mainly used for fundamental physics, but gravimetric measurements can also be performed. Due to the large fall distance and the resulting long fall time of the atoms, a future accuracy in the range of 1 nm/s² is anticipated. With classical transportable absolute gravimeters, however, some tens nm/s² are achieved. The VLBAI could therefore be a reference for classical gravimeters. For these experiments and for the evaluation of the error budget, however, knowledge of the local gravitational field is necessary. This will be determined in parallel to the installation of the large-scale instrument and further on by gravimetric measurements and forward modelling.

  Led by: Dr.-Ing. Manuel Schilling, Dr.-Ing. Ludger Timmen

  Team: Dr.-Ing. Manuel Schilling, Dr.-Ing. Ludger Timmen

  Year: 2017

  Funding: IfE, SFB-1128, EXC-2123 "QuantumFrontiers"

  Duration: 2017-2025

  © M. Schilling
• A mobile absolute gravimeter based on atom interferometry for highly accurate point observations

  Atom interferometers have demonstrated a high sensitivity to inertial forces. The Gravimetric Atom Interferometer (GAIN), developed at Humboldt-Universität zu Berlin, is a mobile atom interferometer based on interfering ensembles of laser-cooled Rb-87 atoms in an atomic fountain configuration. In the continued development state-of-the-art superconductiong gravimeters and laser-interferometer based absolute gravimeters are used for comparisons with and the characterization of GAIN.

  Led by: Prof. Dr.-Ing. Jürgen Müller

  Team: M. Sc. Manuel Schilling

  Year: 2012

  Funding: DFG

  © IFE / M. Schilling

Gravity Field and Geoid Modelling

• Modelling of Mass Variations Down to Small Scales by Quantum Sensor Fusion (CRC 1464, C05)

  Observing the temporal variations of the Earth gravity field by satellite gravimetry, terrestrial gravimetry or loading time series via GNSS gives insight into the temporal and spatial changes in the distribution of water on various scales. The overall aim of this project is to develop models of regional time-variable gravity (or, equivalently, of total water storage variations) at uttermost high spatial and temporal resolution by the consistent integration of the various geodetic sensors. The project thus tackles one of the currently most pressing challenges in geodesy and its dependent geophysical applications.

  Led by: Prof. Dr.-Ing. Annette Eicker, Prof. Dr. Andreas Günther, Dr. Matthias Weigelt

  Team: Marvin Reich

  Year: 2021

  Funding: DFG
• Quantum-based acceleration measurement on geodesy satellites (Q-BAGS)

  Collaboration between the Observatoire de Paris Department Systèmes de référence temps-espace (SYRTE) and the Institute of Geodesy (IfE) of Leibniz Universität Hannover (LUH) embedded in the QUANTA research cooperation between Germany and France.

  Led by: Prof. Dr.-Ing. habil. Jürgen Müller

  Team: Annike Knabe

  Year: 2021

  Funding: BMWK / DLR e.V. (50WM2181)

  Duration: 10/2021 - 09/2024
• COST-G: International Combination Service for Time-variable Gravity Field Solutions

  COST-G ist ein zukünftiges Produktzentrum des IGFS (International Gravity Field Service), welches das Ziel hat kombinierte monatliche Schwerefelder bereitzustellen. Hierbei werden die von den einzelnen Analysezentren berechneten Normalgleichungsmatrizen der Schwerefeldparameter aufbauend auf eigens für den Service definierten Qualitätsmerkmalen empirisch gewichtet, gelöst und validiert.

  Led by: Prof. Jakob Flury

  Team: M.Sc. Igor Koch

  Year: 2019
• Europäische Geoidberechnungen

  Led by: Dr.-Ing. Heiner Denker

  Team: Dr.-Ing. Heiner Denker

  Year: 2019

  Funding: verschiedene Landes- und Drittmittel; Unterstützung durch Internationale Assoziation für Geodäsie (IAG)

  Duration: seit 1990
• QuantumFrontiers (EXC2123) / Research Unit Relativistic Geodesy

  Led by: Prof. Dr. Karsten Danzmann (AEI), Prof. Dr. Claus Lämmerzahl (ZARM)

  Team: Dr.-Ing. Heiner Denker u. a.

  Year: 2019

  Funding: Deutsche Forschungsgemeinschaft (DFG)
• Gravity field recovery from satellite-to-satellite tracking data

  Das Institut für Erdmessung berechnet und publiziert globale monatliche Schwerefelder aus Sensordaten der Multisatellitenmission GRACE. Zentrale Aspekte der Schwerefeldbestimmung und Forschungsgegenstand dieses Projektes sind die Sensorfusion, die Modellierung von konservativen und nicht-konservativen Störkräften, die numerische Integration der Satellitenbewegung, die Anpassung von modellierten Satellitenbahnen an Beobachtungen durch iterative Schätzverfahren, sowie die Parametrisierung der Satellitenbewegung.

  Led by: Prof. Jakob Flury

  Team: M.Sc. Igor Koch

  Year: 2018

  © IfE / I. Koch
• German Combined Geoid 2016 (GCG2016)

  Led by: Dr.-Ing. Heiner Denker

  Team: Dr.-Ing. Heiner Denker

  Year: 2016
• High-resolution modeling of geoid-quasigeoid separation

  Led by: Prof. Dr.-Ing. Jakob Flury

  Year: 2013

Relativistic Geodesy

• Terrestrial Clock Networks: Fundamental Physics and Applications (CRC 1464, C02)

  The continuous developments of optical clocks and the long-distance links via fibers, especially within TerraQ, will give access to terrestrial clock networks in practice, which will enable the novel measurement concept of chronometric levelling. From a theoretical perspective, this project will elaborate the rigorous relativistic formalism for clock-based geodesy and assess the effects of approximations in different scenarios. Furthermore, this project will figure out the most promising applications for clock networks in geodesy and fundamental physics.

  Led by: Prof. Dr.-Ing. Jürgen Müller, Prof. Dr. Claus Lämmerzahl

  Team: Marion Cepok, Asha Vincent

  Year: 2021

  Funding: DFG
• Differential Lunar Laser Ranging

  Led by: Prof. Dr.-Ing. habil. Jürgen Müller

  Team: M. Sc. Mingyue Zhang

  Year: 2021

  Funding: Germany’s Excellence Strategy – EXC-2123 QuantumFrontiers (DFG), DLR-SI

  Duration: 2021 - 2022
• Improved modelling of the Earth-Moon system

  Led by: Prof. Dr.-Ing. Jürgen Müller

  Team: Vishwa Vijay Singh, M.Sc.

  Year: 2020

  Funding: DLR-SI

  Duration: 2019 - 2022
• Relativistic investigations with LLR data

  Led by: Prof. Dr.-Ing. habil. Jürgen Müller

  Team: Dr.-Ing. Liliane Biskupek

  Year: 2019

  Funding: Germany’s Excellence Strategy – EXC-2123 QuantumFrontiers (DFG)

  Duration: 2019 - 2025
• Chronometrisches Nivellement

  Led by: Dr.-Ing. Heiner Denker

  Team: Dr.-Ing. Heiner Denker und weitere Mitarbeiter

  Year: 2019

  Funding: verschiedene Landes- und Drittmittel sowie separate Projekte

  Duration: seit 2010
• High-performance clock networks and their application in geodesy

  The rapid development of optical clocks and frequency transfer techniques provides the opportunity to compare clocks’ frequencies at the uncertainty level of 10-18. This will enable relativistic geodesy with the aimed accuracy of cm in terms of height. Clock networks are thus highly relevant to various geodetic applications, such as the realization of a height reference system and the determination of regional/global gravity fields. In this project, we aim to investigate the potential of high-performance clock networks and quantify their contributions to specific applications through dedicated simulations.

  Led by: Prof. Dr.-Ing. Jürgen Müller

  Team: Dr.-Ing. Hu Wu

  Year: 2019

  Funding: Germany’s Excellence Strategy – EXC-2123 “QuantumFrontiers” (DFG)
• Relativistische Geodäsie in Netzen optischer Atomuhren

  Led by: Prof. Dr.-Ing. Jakob Flury

  Year: 2018

  Duration: seit 2018

Satellite Gravimetry

• New Measurement Concepts with Laser Interferometers (CRC 1464, B01)

  We will study a new type of optical accelerometer (ACC) and gradiometer, advance Laser Ranging Interferometry (LRI) technology conceptually to enable new satellite constellations, and investigate observations of the angular line-of-sight velocity for gravity field recovery with simulations.

  Led by: Prof. Dr.-Ing. Jürgen Müller, Dr. Vitali Müller

  Team: Alexey Kupriyanov, Arthur Reis

  Year: 2021

  Funding: DFG

  Duration: 2021-2024
• Hybridization of Classic and Quantum Accelerometers for Future Satellite Gravity Missions

  Using cold atom interferometry (CAI) accelerometers in the next generation of satellite gravimetry missions can provide long-term stability and precise measurements of the non-gravitational forces acting on the satellites. This allows for a reduction of systematic effects in current GRACE-FO gravity field solutions. In this project, we first aim to investigate the hybridization of quantum CAI-based and classical accelerometers for a GRACE-like mission and we discusse the performance improvement through dedicated simulations. Then we investigate different orbital configurations and mission concepts to find the optimal setting for future satellite gravimetry missions.

  Led by: Prof. Dr.-Ing. Müller

  Team: Dr. Alireza HosseiniArani

  Year: 2020
• 3D Earth – A Dynamic Living Planet

  The goal of 3D-Earth is to establish a global 3D reference model of the crust and upper mantle based on the analysis of satellite gravity e.g. GOCE and (electro-)magnetic missions e.g. Swarm in combination with seismological models and analyse the feedback between processes in Earth’s deep mantle and the lithosphere. Selected case examples will provide the possibility to test these approaches on a global and regional scale. This will result in a framework for consistent models that will be used to link the crust and upper mantle to the dynamic mantle.

  Led by: Prof. Dr.-Ing. Jakob Flury

  Team: Dr.-Ing. Akbar Shabanloui

  Year: 2017

  Funding: ESA

  Duration: 2017-2019
• Earth System Mass Transport Mission (e.motion)

  Led by: Jakob Flury

  Year: 2013

Antenna Calibration

• Gewinn eines grundlegenden Verständnisses der Mehrwege - Antennen - Empfänger - Interaktionen zur Standardisierung der Kalibrierung von Codephasenvariationen von GNSS-Empfangsantennen

  Led by: Prof. Dr.-Ing. Steffen Schön, Dr.-Ing. Tobias Kersten

  Team: Yannick Breva

  Year: 2022

  Funding: DFG, Project number: 470510446
• GPS Codephasen-Variationen für GNSS-Empfangsantennen

  Neben der sehr gut bekannten Existenz von Abweichungen des Empfangszentrums von GNSS-Antennen für Trägerphasen sind gleiche Effekte auch auf der Codephase (Code Phase Variations CPV) gefunden worden. Diese Abweichungen sind stark von der Beschaffenheit und Qualität der Empfangsantennen abhängig und nehmen gerade bei Massenmarktprodukten erhebliche Abweichungen an. Der Nachweis über die Charaktersitik der Codephasen-Variationen ist besonders für Navigationsanwendungen wichtig, da zum einen die Antennen notwendigen Spezifikationen entsprechen müssen und zum anderen die Präzision des Sensors durch Berücksichtigung dieser individuellen Kalibrierwerte deutlich verberssert werden können.

  Led by: Dr.-Ing. Tobias Kersten

  Team: Yannick Breva, Johannes Kröger

  Year: 2018
• Trägerphasenvariationen (PCC) für neue GNSS-Signale

  Trägerphasenvaritionen sind überaus notwendig für die präzise GNSS-Navigation und Positionierung. Derzeit werden nur GPS L1/L2 und GLONASS L1/L2 im Rahmen der operationellen roboterbasierten Kalibierung zur Verfügung gestellt. Die Weiterentwicklung der individuellen Satellitensysteme (GPS, GLONASS) und die Entwicklung von neuen Systemen (Galileo, Beidou) erfordern die Weiterentwicklung des Kalibrierverfahrens zur Bestimmung entsprechender Parameter neuer Systeme und Frequenzen. Ziel des Projektes ist die Bereitstellung und konsistente Verarbeitung von Kalibrierwerten für GPS L5 und Galileo E1/E5 Signalen auf Basis von Kugelfunktionsentwicklungen. Erhobene Phasenpattern werden mit Kalibrierwerten anderer Institutionen vergleichen und koordiniert ausgetauscht.

  Led by: Dr.-Ing. Tobias Kersten

  Team: Johannes Kröger, Yannick Breva

  Year: 2018

GNSS and Inertial Navigation

• Interferometric Fibre Links (CRC 1464, A05)

  The overarching goal, to establish chronometric levelling as a routine tool for geodesy, requires research and developments for high precision frequency transfer in the areas of Interferometric Fibre Links (IFLs) and Global Naviation Satellite System - Frequency Transfer (GNSS-FT). The development of fieldable IFLs equipment, ultraprecise GNSS-FT and their use for chronometric levelling, are new areas of research and development, which will open up many applications of geodetic interest. We aim to realise an island-mainland chronometric levelling campaign using IFL and GNSS-FT, and the transportable optical clocks developed in A04.

  Led by: Prof. Dr.-Ing. Steffen Schön, Dr. Gesine Grosche

  Team: Dr. Alexander Kuhl, Dr. Thomas Waterholter, Ahmed Elmaghraby

  Year: 2021

  Funding: DFG
• FIRST: Fingerprinting, Integrity Monitoring and Receiver Signal Processing Using Miniature Atomic Clock Technology

  In order to improve the performance of the determination of position, velocity and time by means of GNSS measurements, nowadays Chip Scale Atomic Clocks (CSACs) are frequently used, which provide a highly stable frequency signal to the GNSS receiver. However, until now, the improvement of the navigation solution has only been algorithmic. In this project, the influence of the receiver clock on the quality of signal processing in a software receiver will be investigated by adapting the internal processing steps to the high frequency stability of the CSAC signal. In addition, the feasibility of fingerprinting with highly stable atomic clocks under different dynamic conditions will be investigated and additional integrity measures for GNSS-based time transfer will be developed.

  Led by: Prof. Dr.-Ing. Steffen Schön

  Team: Dennis Kulemann, M. Sc., Qianwen Lin, M. Sc.

  Year: 2020

  Funding: Bundesministerium für Wirtschaft und Energie (BMWi)
• Correction of GNSS multipath effects for reliable autonomous localisation of highly automated vehicles in metropolitan areas (KOMET)

  The code range (code measurement) used in automotive applications often cannot provide the required resolution of the location due to the high measurement noise. The complex GNSS signal propagation (signal shading, multipath effects) in urban environments makes the determination of an accurate and robust positioning solution a particularly challenging task - e.g. for positioning in narrow street canyons. The research project aims to develop and implement innovative correction methods to reduce multipath effects in order to improve carrier phase-based GNSS positioning.

  Led by: Prof. Dr.-Ing. Steffen Schön, Dr.-Ing. Tobias Kersten

  Team: Dr.-Ing. Tobias Kersten, M.Sc. Fabian Ruwisch

  Year: 2020

  Funding: BMWi / TÜV Rheinland Consulting GmbH

  © Ch. Skupin (Bosch)
• Bounding and propagating observation uncertainty with interval mathematic (GRK 2159)

  Intervals (Jaulin et al 2001) can be seen as a natural way to bound observation uncertainty in navigation systems such as GPS, IMU or optical sensors like LIDAR, since they are in principle free of any assumption about probability distributions and can thus describe adequately remaining systematic effects (Schön 2016, Schön and Kutterer 2006). In this project, we intent to experimentally investigate in more details the actual size of observation intervals.

  Led by: Prof. Dr.-Ing. Steffen Schön

  Team: Jingyao Su, M.Sc.

  Year: 2020

  Funding: DFG
• Collaborative Navigation for Smart Cities (GRK 2159)

  Global Navigation Satellite Systems (GNSS) is the only navigation sensor that provides absolute positioning. However, urban areas form the most challenging environment for GNSS to achieve a reliable position. Because of the reduced satellite visibility and disturbed signal propagation like diffraction and multipath, the resulting position has a reduced accuracy and availability. The overall research objective of this project is to reduce these shortcomings through collaboration. Therefore, similarity of multipath at different locations within streets will be studied.

  Led by: Prof. Dr.-Ing. Steffen Schön

  Team: Lucy Icking, M.Sc.

  Year: 2019

  Funding: DFG
• QGyro: Quantum Optics Inertial Sensor Research

  The objective of this research programme is to develop and test high-precision quantum inertial sensors that support conventional inertial navigation sensors in order to expand these sensors to up to 6 degrees of freedom and use them for autonomous navigation in various further development stages.

  Led by: Prof. Dr.-Ing. Steffen Schön

  Team: M.Sc. Benjamin Tennstedt, Dr.-Ing. Tobias Kersten

  Year: 2019

  Funding: BMWi | German Aerospace Centre (DLR) - 50RK1957

  Duration: 2019 - 2022
• Integrity Monitoring for Network RTK Systems

  From the advent of the satellite positioning techniques, civil users have always been trying to find a way to have more accurate and precise coordinates of their position. Differential concepts, from early days of GPS, have been considered. Applying the RTCM format, made the transmission of corrections possible from reference stations to the users. At first stage the corrections were casted to the users from one single station, which is called single RTK (Real Time Kinematic). This method is limited in some ways; degrading by increasing distance from CORS (Continuously Operating Reference Station), needed same signals at reference and rover and remaining the reference station errors. For compensating these shortages, the Network RTK concept appeared. In NRTK the corrections are produced using a network (at least three) of reference stations. The concept of Precise Point Positioning (PPP) is currently associated with global networks. Precise orbit and clock solutions are used to enable absolute positioning of a single receiver. However, it is restricted in ambiguity resolution, in convergence time and in accuracy. Precise point positioning based on RTK networks (PPP-RTK) overcomes these limitations and gives centimeter-accuracy in a few seconds.

  Led by: Prof. Dr.-Ing. Steffen Schön

  Team: Ali Karimidoona, M. Sc.

  Year: 2018

  Funding: DAAD
• Entwicklung und Test einer für Quantensensoren adäquaten Berechnungsstrategie für die Inertialnavigation

  Durch neue Messprinzipien haben Quantensensoren signifikante Verbesserungen in Stabilität und Genauigkeit bei der Erfassung von inertialen Einflüssen erzielt. Anstelle mechanischer Federsysteme in Beschleunigungsmessern oder durch einen Faserkreisel oder Ringresonator umschlossene Flächen in Lasergyroskopen sind in Quantensensoren die Skalenfaktoren an atomare Übergänge gebunden und auf Frequenzmessungen zurückzuführen. Die alternativen Messverfahren und hohen Sensitivitäten der Quantensensoren erfordern eine adäquate Auswertestrategie, die sich von der klassischen Herangehensweise der Inertialnavigation unterscheidet. Ziel der Studie ist die Entwicklung und der Test einer entsprechenden Berechnungsstrategie, die gezielt die Anwendbarkeit der einzelnen Berechnungsschritte bei der Quanteninertialnavigation überprüft, und geeignete Alternativen, beispielsweise bei der Integrationsdynamik oder geschätzten Systemparametern, vorschlägt.

  Led by: Prof. Dr.-Ing. Steffen Schön

  Team: M.Sc. Benjamin Tennstedt

  Year: 2018

  Funding: DLR
• VeNaDU 2: Verbesserte Positionierung und Navigation durch Uhrmodellierung

  Dieses Folgeprojekt zum Vorhaben VeNaDU untersucht zum einen den Performance-Gewinn durch den Einsatz hochstabiler Atomuhren in kinematischem PPP. Zum anderen soll eine Hardware-technische Umsetzung einer miniaturisierten Atomuhr in einem Einfrequenz-Empfänger realisiert werden.

  Led by: Prof. Dr.-Ing. Steffen Schön

  Team: Dr.-Ing. Thomas Krawinkel, Dr. Ankit Jain

  Year: 2017
• Improved GPS data analysis for the Swarm constellation

  New concepts for GPS observation data quality assessment and positioning should be developed and evaluated taking advantage of variable geometries in the Swarm constellation.

  Led by: Prof. Dr.-Ing. Steffen Schön

  Team: Dipl.-Ing. Le Ren

  Year: 2015

  Funding: DFG

Lunar Laser Ranging (LLR)

• Differential Lunar Laser Ranging

  Led by: Prof. Dr.-Ing. habil. Jürgen Müller

  Team: M. Sc. Mingyue Zhang

  Year: 2021

  Funding: Germany’s Excellence Strategy – EXC-2123 QuantumFrontiers (DFG), DLR-SI

  Duration: 2021 - 2022
• Improved modelling of the Earth-Moon system

  Led by: Prof. Dr.-Ing. Jürgen Müller

  Team: Vishwa Vijay Singh, M.Sc.

  Year: 2020

  Funding: DLR-SI

  Duration: 2019 - 2022
• LLR contribution to reference frames and Earth orientation parameters

  Led by: Prof. Dr.-Ing. Jürgen Müller

  Team: Dr.-Ing. Liliane Biskupek

  Year: 2019

  Funding: Germany’s Excellence Strategy – EXC-2123 QuantumFrontiers (DFG), DLR-SI

  Duration: 2019 - 2025
• Relativistic investigations with LLR data

  Led by: Prof. Dr.-Ing. habil. Jürgen Müller

  Team: Dr.-Ing. Liliane Biskupek

  Year: 2019

  Funding: Germany’s Excellence Strategy – EXC-2123 QuantumFrontiers (DFG)

  Duration: 2019 - 2025

Space Sensor Technologies

• Modellierung mit Quantensensoren gestützter Satellitenmissionen

  Dieses Projekt beschreibt den den Einsatz von Beschleunigungsmessern auf Grundlage von Atominterferometern in Schwerefeldsatellitenmissionen. Es wird sowohl der Ersatz klassischer elektrostatischer Beschleunigungsmesser durch Quantensensoren als auch die Kombination beider Sensorarten in einem Hybridsystem untersucht.

  Led by: Prof. Dr.-Ing. Jürgen Müller

  Team: M.Sc. Annike Knabe, Dr.-Ing. Hu Wu, Dr.-Ing. Manuel Schilling

  Year: 2019

  Funding: DLR

  © Schilling
• Interactions of Low-orbiting Satellites with the Surrounding Ionosphere and Thermosphere Part II (INSIGHT II)

  At our Institute, we provide reduced and calibrated Swarm accelerometer data for the ESA Swarm data processing chain that are the basis for the determination of thermospheric density. This includes the accelerometer calibration by precise orbit determination of Swarm satellites.

  Led by: Prof. Dr.-Ing. Jakob Flury

  Team: Dr.-Ing. Akbar Shabanloui

  Year: 2018

  Funding: DFG

  Duration: 2018-2021
• Swarm ESL/DISC: Support to accelerometer data analysis and processing

  Led by: Prof. Dr.-Ing. Jakob Flury

  Team: Dr.-Ing. Sergiy Svitlov, Dr.-Ing. Akbar Shabanloui

  Year: 2016

  Funding: ESA (DTU Space)

  Duration: 2016-2020

EXC-2123 QuantumFrontiers

• Differential Lunar Laser Ranging

  Led by: Prof. Dr.-Ing. habil. Jürgen Müller

  Team: M. Sc. Mingyue Zhang

  Year: 2021

  Funding: Germany’s Excellence Strategy – EXC-2123 QuantumFrontiers (DFG), DLR-SI

  Duration: 2021 - 2022
• Relativistic investigations with LLR data

  Led by: Prof. Dr.-Ing. habil. Jürgen Müller

  Team: Dr.-Ing. Liliane Biskupek

  Year: 2019

  Funding: Germany’s Excellence Strategy – EXC-2123 QuantumFrontiers (DFG)

  Duration: 2019 - 2025

CRC 1464 (TerraQ)

• Terrestrial Clock Networks: Fundamental Physics and Applications (CRC 1464, C02)

  The continuous developments of optical clocks and the long-distance links via fibers, especially within TerraQ, will give access to terrestrial clock networks in practice, which will enable the novel measurement concept of chronometric levelling. From a theoretical perspective, this project will elaborate the rigorous relativistic formalism for clock-based geodesy and assess the effects of approximations in different scenarios. Furthermore, this project will figure out the most promising applications for clock networks in geodesy and fundamental physics.

  Led by: Prof. Dr.-Ing. Jürgen Müller, Prof. Dr. Claus Lämmerzahl

  Team: Marion Cepok, Asha Vincent

  Year: 2021

  Funding: DFG
• Interferometric Fibre Links (CRC 1464, A05)

  The overarching goal, to establish chronometric levelling as a routine tool for geodesy, requires research and developments for high precision frequency transfer in the areas of Interferometric Fibre Links (IFLs) and Global Naviation Satellite System - Frequency Transfer (GNSS-FT). The development of fieldable IFLs equipment, ultraprecise GNSS-FT and their use for chronometric levelling, are new areas of research and development, which will open up many applications of geodetic interest. We aim to realise an island-mainland chronometric levelling campaign using IFL and GNSS-FT, and the transportable optical clocks developed in A04.

  Led by: Prof. Dr.-Ing. Steffen Schön, Dr. Gesine Grosche

  Team: Dr. Alexander Kuhl, Dr. Thomas Waterholter, Ahmed Elmaghraby

  Year: 2021

  Funding: DFG
• Optical Clocks for Chronometric Levelling (CRC 1464, A04)

  We will realise the potential of chronometric levelling by demonstrating off-campus height measurements with the same or better resolution than geometric levelling and the Global Navigation Satellite System (GNSS)/geoid approach can presently achieve, in joint campaigns with project A05. This demonstration will be strengthened by the application of our measurement capabilities to geodetic problems of high relevance through cooperation with the TerraQ projects employing gravimetric and GNSS techniques to e.g. monitor water storage and other mass changes (projects Terrestrial Clock Networks: Fundamental Physics and Applications (C02), Modelling of Mass Variations Down to Small Scales by Quantum Sensor Fusion (C05), and Atmosphere-Ocean Background Modelling for Terrestrial Gravimetry (C06)).

  Led by: PD Dr. Christian Lisdat, Prof. Dr. Piet O. Schmidt, Dr.-Ing. Denker

  Team: Tim Lücke, Constantin Nauk

  Year: 2021

  Funding: DFG
• Validation of Quantum Gravimeter QG-1 for Hydrology (CRC 1464, C01)

  For the groundwater management in central Europe, ground-based gravimetry provides a unique potential to monitor temporal variations in the subsurface water content for local areas. The atomic Quantum Gravimeter-1 (QG-1) of Leibniz Universität Hannover (LUH) is in its final phase of development (A01) and will be ready for geodetic and gravimetric applications latest in 2021. The QG-1 capability will be demonstrated indoor and also in a field application as an advanced absolute gravimeter allowing effectively the surveying of gravity variations due to groundwater changes on the uncertainty level of 10 nm/s².

  Led by: Dr.-Ing. Heiner Denker, Dr.-Ing. Ludger Timmen

  Team: Dinesh Chebolu

  Year: 2021

  Funding: DFG
• Gravity Field Solution by Exploiting the Full Potential of GRACE Follow-On (SFB 1464, C04)

  The overall aim of this project is to take maximum advantage of the data of the GRACE and GRACE-FO missions and derive the best possible time-variable gravity field with monthly and daily solution. We anticipate an increased spatial resolution and a reduction of systematic errors due to improved background modelling and co-estimation of geophysical and instrumental parameters.

  Led by: Dr. Matthias Weigelt, Prof. Dr.-Ing. Torsten Mayer-Gürr

  Team: Sahar Ebadi

  Year: 2021

  Funding: DFG
• Quantum Gravimetry (CRC 1464, A01)

  Within TerraQ we aim to establish atom-chip based Quantum Gravimetry with Bose-Einstein condensates (BECs) and explore its potential for mobile gravimetry. Deploying QG-1 (Quantum Gravimeter) with steadily increasing frequency and performance in measurement campaigns for C01, A05 and C05 will allow us to prove the in-field applicability of the associated methods and demonstrate an operation of QG-1 under varying, rough conditions.

  Led by: Dr. Waldemar Herr, Prof. Dr.-Ing. Jürgen Müller, Prof. Dr. Ernst Rasel

  Team: Nina Heine, Marat Musakaev

  Year: 2021

  Funding: DFG
• Atmosphere-Ocean Background Modelling for Terrestrial Gravimetry (CRC 1464, C06)

  We will focus on the development of global background models of atmosphere and ocean dynamics that are applicable to gravity records taken anywhere at the Earth’s surface. The background models will be split into deformation effects that also consider the laterally heterogeneous rheology of the Earth’s crust, regional-to-global attraction effects of both atmospheric and oceanic mass variability along the strategy outlined by, and the local effects from the direct vicinity of the sensor that are most sensible to the local topographic roughness and that might benefit most from a possible augmentation with barometric observations taken around the gravity sensor.

  Led by: Dr. Henryk Dobslaw, Dr.-Ing. Ludger Timmen

  Team: Dr. Kyriakos Balidakis

  Year: 2021

  Funding: DFG
• Modelling of Mass Variations Down to Small Scales by Quantum Sensor Fusion (CRC 1464, C05)

  Observing the temporal variations of the Earth gravity field by satellite gravimetry, terrestrial gravimetry or loading time series via GNSS gives insight into the temporal and spatial changes in the distribution of water on various scales. The overall aim of this project is to develop models of regional time-variable gravity (or, equivalently, of total water storage variations) at uttermost high spatial and temporal resolution by the consistent integration of the various geodetic sensors. The project thus tackles one of the currently most pressing challenges in geodesy and its dependent geophysical applications.

  Led by: Prof. Dr.-Ing. Annette Eicker, Prof. Dr. Andreas Günther, Dr. Matthias Weigelt

  Team: Marvin Reich

  Year: 2021

  Funding: DFG
• New Measurement Concepts with Laser Interferometers (CRC 1464, B01)

  We will study a new type of optical accelerometer (ACC) and gradiometer, advance Laser Ranging Interferometry (LRI) technology conceptually to enable new satellite constellations, and investigate observations of the angular line-of-sight velocity for gravity field recovery with simulations.

  Led by: Prof. Dr.-Ing. Jürgen Müller, Dr. Vitali Müller

  Team: Alexey Kupriyanov, Arthur Reis

  Year: 2021

  Funding: DFG

  Duration: 2021-2024