Ch. Reigber

Bio: Ch. Reigber is an academic researcher from Deutsches Geodätisches Forschungsinstitut. The author has contributed to research in topics: Radio occultation & Radiosonde. The author has an hindex of 10, co-authored 20 publications receiving 1509 citations.

First champ mission results for gravity, magnetic and atmospheric studies

Abstract: I Orbit and Earth Gravity Field.- CHAMP Orbit and Gravity Instrument Status.- On Board Evaluation of the STAR Accelerometer.- Determination of CHAMP Accelerometer Calibration Parameters.- CHAMP Accelerometer and Star Sensor Data Combination.- CHAMP Clock Error Characterization.- Determination of the CHAMP GPS Antenna with Respect to Satellite's Mass Center.- Spaceborne GPS for POD and Earth Science.- The CHAMP Orbit Comparison Campaign.- CHAMP Orbit Determination with GPS Phase-Connected, Precise Point Positioning.- Kinematic and Dynamic Determination of Trajectories for Low Earth Satellites Using GPS.- CHAMP Double-Difference Kinematic POD with Ambiguity Resolution.- Approaches to CHAMP Precise Orbit Determination.- STAR Accelerometer Contribution to Dynamic Orbit and Gravity Field Model Adjustment.- Impact of Different Data Combinations on the CHAMP Orbit Determination.- CHAMP Rapid Science Orbit Determination - Status and Future Prospects.- Orbit Predictions for CHAMP - Development and Status.- Thermospheric Events in CHAMP Precise Orbit Determination.- New Global Gravity Field Models from Selected CHAMP Data Sets.- First Insight into Temporal Gravity Variablility from CHAMP.- CHAMP Gravity Field Recovery with the Energy Balance Approach.- Preliminary Analysis of CHAMP State Vector and Accelerometer Data for the Recovery of the Gravity Potential.- CHAMP Precise Orbit Determination and Gravity Field Recovery.- Gravitational Field Modelling from CHAMP-Ephemerides by Harmonic Splines and Fast Multipole Techniques.- Evaluation of Geoid Models with GPS/Levelling Points in Sweden and Finland.- Geophysical Impact of Field Variations.- CHAMP, Mass Displacements and the Earth's Rotation.- CHAMP Gravity Anomalies over Antarctica.- Assimilation of Altimeter and Geoid Data into a Global Ocean Model.- Total Density Retrieval with STAR.- II Earth Magnetic Field.- CHAMP ME Data Processing and Open Issues.- Ion Drift-Meter Status and Calibration.- CO2 - A CHAMP Magnetic Field Model.- Decadal and Subdecadal Secular Variation of Main Geomagnetic Field.- Modelling the Earth's Magnetic Field: Wavelet Based and Standard Methods.- Improved Parameterization of External Magnetic Fields from CHAMP Measurements.- Monitoring Magnetospheric Contributions using Ground-Based and Satellite Magnetic Data.- Unraveling the Magnetic Mystery of the Earth's Lithosphere: The Background and the Role of the CHAMP Mission.- A Comparison of Global Lithospheric Field Models Derived from Satellite Magnetic Data.- Mapping the Lithospheric Magnetic Field from CHAMP Scalar and Vector Magnetic Data.- Improving the Definition of Cratonic Boundaries Utilizing the Lithospheric Magnetic Field derived from CHAMP Observations.- Crustal Magnetisation Distribution Deduced from CHAMP Data.- Multiscale Downward Continuation of CHAMP FGM-Data for Crustal Field Modelling.- CHAMP Enhances Utility of Satellite Magnetic Observations to Augment Near-Surface Magnetic Survey Coverage.- Comparing Magsat, Orsted and CHAMP Crustal Magnetic Anomaly Data over the Kursk Magnetic Anomaly, Russia.- CHAMP, Orsted and Magsat Magnetic Anomalies of the Antarctic Lithosphere.- Separation of External Magnetic Signal for Induction Studies.- Two-Dimensional Spatiotemporal Modelling of Satellite Electromagnetic Induction Signals.- Night-Time Ionospheric Currents.- Multiscale Determination of Radial Current Distribution from CHAMP FGM-Data.- Ionospheric Currents from CHAMP Magnetic Field Data - Comparison with Ground Based Measurements.- Mapping of Field-Aligned Current Patterns during Northward IMF.- Field-Aligned Currents Inferred from Low-Altitude Earth-Orbiting Satellites and Ionospheric Currents Inferred from Ground-Based Magnetometers - Do They Render Consistent Results?.- III Neutral Atmosphere and Ionosphere.- GPS Radio Occultation with CHAMP.- Validation and Data Quality of CHAMP Radio Occultation Data.- Global Climate Monitoring based on CHAMP/GPS Radio Occultation Data.- Initial Results on Ionosphere/Plasmasphere Sounding based on GPS Data Obtained On Board CHAMP.- Backpropagation Processing of GPS Radio Occultation Data.- Combination of NOAA16/ATOVS Brightness Temperatures and the CHAMP Data to get Temperature and Humidity Profiles.- An Improvement of Retrieval Techniques for Ionospheric Radio Occultations.- Validation of Water Vapour Profiles from GPS Radio Occultations in the Arctic.- Comparison of DMI-Retrieval of CHAMP Occultation Data with ECMWF.- The Assimilation of Radio Occultation Measurements.- Status of Ionospheric Radio Occultation CHAMP Data Analysis and Validation of Higher Level Data Products.- NWP Model Specific Humidities Compared with CHAMP/GPS and TERRA/MODIS Data.- Analysis of Gravity Waves from Radio Occultation Measurements.- GPS Atmosphere and Ionosphere Methods used on Orsted Data and Initial Application on CHAMP Data.- Combining Radio Occultation Measurements with Other Instruments to Map the Ionospheric Electron Concentration.- Vertical Gradients of Refractivity in the Mesosphere and Atmosphere Retrieved from GPS/MET and CHAMP Radio Occultation Data.- Observation of Reflected Signals in MIR/GEO and GPS/MET Radio Occultation Missions.- Assimilation Experiments of One-dimensional Variational Analyses with GPS/MET Refractivity.- Monitoring the 3 Dimensional Ionospheric Electron Distribution based on GPS Measurements.- Comparison of Three Different Meteorological Datasets (ECMWF, Met Office and NCEP).- Radio Occultation Data Processing at the COSMIC Data Analysis and Archival Center (CDAAC).- Verification of CHAMP Radio-Occultation Observations in the Ionosphere Using MIDAS.- Approach to the Cross-Validation of MIPAS and CHAMP Temperature and Water Vapour Profiles.- Author Index.- Keyword Index.

The CHAMP geopotential mission

Abstract: CHAMP is a German small satellite mission aiming at the simultaneous precise observation of both the gravity and magnetic field from a low altitude orbit. Thanks to the dedicated orbit design, an unprecedented low altitude in a near polar orbit, its continuous undisturbed observation of the magnetic field vector through scalar and vector magnetometers and its continuous GPS satellite-to-satellite tracking capability together with a direct on-board measurement of the non-gravitational orbit perturbations, a dramatic improvement in the global modeling of the magnetic field and also an order of magnitude improvement for the broad to mesoscale structures of the gravity field can be expected. In addition, due to the designed 5 years mission duration, temporal changes in both fields will be detectable with a higher signal/noise ratio and at increased spatial resolution as it is possible now. CHAMP was successfully launched on 15 July 2000.

GPS radio occultation with CHAMP and SAC-C: global monitoring of thermal tropopause parameters

Abstract: . In this study the global lapse-rate tropopause (LRT) pressure, temperature, potential temperature, and sharpness are discussed based on Global Positioning System (GPS) radio occultations (RO) from the German CHAMP (CHAllenging Minisatellite Payload) and the U.S.-Argentinian SAC-C (Satelite de Aplicaciones Cientificas-C) satellite missions. Results with respect to seasonal variations are compared with operational radiosonde data and ECMWF (European Centre for Medium-Range Weather Forecast) operational analyses. Results on the tropical quasi-biennial oscillation (QBO) are updated from an earlier study. CHAMP RO data are available continuously since May 2001 with on average 150 high resolution temperature profiles per day. SAC-C data are available for several periods in 2001 and 2002. In this study temperature data from CHAMP for the period May 2001-December 2004 and SAC-C data from August 2001-October 2001 and March 2002-November 2002 were used, respectively. The bias between GPS RO temperature profiles and radiosonde data was found to be less than 1.5K between 300 and 10hPa with a standard deviation of 2-3K. Between 200-20hPa the bias is even less than 0.5K (2K standard deviation). The mean deviations based on 167699 comparisons between CHAMP/SAC-C and ECMWF LRT parameters are (-2.1±37.1)hPa for pressure and (0.1±4.2)K for temperature. Comparisons of LRT pressure and temperature between CHAMP and nearby radiosondes (13230) resulted in (5.8±19.8)hPa and (-0.1±3.3)K, respectively. The comparisons between CHAMP/SAC-C and ECMWF show on average the largest differences in the vicinity of the jet streams with up to 700m in LRT altitude and 3K in LRT temperature, respectively. The CHAMP mission generates the first long-term RO data set. Other satellite missions will follow (GRACE, COSMIC, MetOp, TerraSAR-X, EQUARS) generating together some thousand temperature profiles daily.

The gravity recovery and climate experiment: Mission overview and early results

Abstract: [1] The GRACE mission is designed to track changes in the Earth's gravity field for a period of five years. Launched in March 2002, the two GRACE satellites have collected nearly two years of data. A span of data available during the Commissioning Phase was used to obtain initial gravity models. The gravity models developed with this data are more than an order of magnitude better at the long and mid wavelengths than previous models. The error estimates indicate a 2-cm accuracy uniformly over the land and ocean regions, a consequence of the highly accurate, global and homogenous nature of the GRACE data. These early results are a strong affirmation of the GRACE mission concept.

International Geomagnetic Reference Field: the 12th generation

Abstract: The 12th generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014 by the Working Group V-MOD appointed by the International Association of Geomagnetism and Aeronomy (IAGA). It updates the previous IGRF generation with a definitive main field model for epoch 2010.0, a main field model for epoch 2015.0, and a linear annual predictive secular variation model for 2015.0-2020.0. Here, we present the equations defining the IGRF model, provide the spherical harmonic coefficients, and provide maps of the magnetic declination, inclination, and total intensity for epoch 2015.0 and their predicted rates of change for 2015.0-2020.0. We also update the magnetic pole positions and discuss briefly the latest changes and possible future trends of the Earth’s magnetic field.

International Geomagnetic Reference Field: the eleventh generation

Abstract: The eleventh generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2009 by the International Association of Geomagnetism and Aeronomy Working Group V-MOD. It updates the previous IGRF generation with a definitive main field model for epoch 2005.0, a main field model for epoch 2010.0, and a linear predictive secular variation model for 2010.0–2015.0. In this note the equations defining the IGRF model are provided along with the spherical harmonic coefficients for the eleventh generation. Maps of the magnetic declination, inclination and total intensity for epoch 2010.0 and their predicted rates of change for 2010.0–2015.0 are presented. The recent evolution of the South Atlantic Anomaly and magnetic pole positions are also examined.

Tropical tropopause layer

Abstract: [1] Observations of temperature, winds, and atmospheric trace gases suggest that the transition from troposphere to stratosphere occurs in a layer, rather than at a sharp “tropopause.” In the tropics, this layer is often called the “tropical tropopause layer” (TTL). We present an overview of observations in the TTL and discuss the radiative, dynamical, and chemical processes that lead to its time-varying, three-dimensional structure. We present a synthesis definition with a bottom at 150 hPa, 355 K, 14 km (pressure, potential temperature, and altitude) and a top at 70 hPa, 425 K, 18.5 km. Laterally, the TTL is bounded by the position of the subtropical jets. We highlight recent progress in understanding of the TTL but emphasize that a number of processes, notably deep, possibly overshooting convection, remain not well understood. The TTL acts in many ways as a “gate” to the stratosphere, and understanding all relevant processes is of great importance for reliable predictions of future stratospheric ozone and climate.

Resolution of GPS carrier-phase ambiguities in Precise Point Positioning (PPP) with daily observations

Abstract: Precise Point Positioning (PPP) has been demonstrated to be a powerful tool in geodetic and geodynamic applications. Although its accuracy is almost comparable with network solutions, the east component of the PPP results is still to be improved by integer ambiguity fixing, which is, up to now, prevented by the presence of the uncalibrated phase delays (UPD) originating in the receivers and satellites. In this paper, it is shown that UPDs are rather stable in time and space, and can be estimated with high accuracy and reliability through a statistical analysis of the ambiguities estimated from a reference network. An approach is implemented to estimate the fractional parts of the single-difference (SD) UPDs between satellites in wide- and narrow-lane from a global reference network. By applying the obtained SD-UPDs as corrections to the SD-ambiguities at a single station, the corrected SD-ambiguities have a naturally integer feature and can therefore be fixed to integer values as usually done for the double-difference ones in the network mode. With data collected at 450 stations of the International GNSS Service (IGS) through days 106 to 119 in 2006, the efficiency of the presented ambiguity-fixing strategy is validated using IGS Final products. On average, more than 80% of the independent ambiguities could be fixed reliably, which leads to an improvement of about 27% in the repeatability and 30% in the agreement with the IGS weekly solutions for the east component of station coordinates, compared with the real-valued solutions.