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Finalized PhD Projects

GNSS Reflectometry for Sea Ice Detection

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Yongchao Zhu (Successful finalization December 2018)

Faculty VI - Planning Building Environment, Technical University Berlin
School of Geodesy and Geomatics, Wuhan University
GFZ Potsdam


Global Navigation Satellite System (GNSS) has been widely used to provide positioning, navigation and timing services in civil and military domains since it became fully operational in 1993. In addition to these fundamental services and applications, GNSS could be also used for remote sensing of atmospheric parameters; for instance, by launching LEO satellites and observing refraction signals from GNSS satellites with negative elevation angles. This GNSS-based remote sensing technique termed GNSS radio occultation (GNSS-RO) could be used to estimate the tropospheric water vapor, temperature, pressure, and ionospheric total electron content (TEC) with a high resolution. Meanwhile, GNSS signal reflection over a specific surface, a source of positioning error, which cannot be easily neutralized, could be used to retrieve the surface geophysical parameters. This remote sensing technique is termed GNSS Reflectometry (GNSS-R). The ocean’s surface characteristics (ie. ocean surface height, roughness, wind speed and wind direction) could be estimated by GNSS-R. It could be also applied for land applications such as the retrieval of ground vegetation condition and soil moisture. This study focuses on sea ice detection using GNSS-R. more to: GNSS Reflectometry for Sea Ice Detection

GPS Reflectometry: Innovative Flood Monitoring at the Mekong Delta

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Jamila Beckheinrich (Successful finalization June 2016)

Faculty VI - Planning Building Environment, Technical University Berlin

Ground-based gauge instrumentation enables a high altimetric accuracy with high temporal resolution, but for a point location only. However, the number of gauge instruments is decreasing worldwide due to high maintenance costs. Global Positioning System-Reflectometry (GPS-R) reveals new perspectives for water level monitoring, since water surfaces show a high reflectivity for the GPS L-band signal. To test the possibility of using this innovative technique as a gauge instrument, two field campaigns were conducted in Vietnam, in February 2012 and March 2013 respectively, within the Water related Information system for the Sustainable Development Of the Mekong delta (WISDOM) project. more to: GPS Reflectometry: Innovative Flood Monitoring at the Mekong Delta

Analysis and Derivation of the Spatial and Temporal Distribution of Water Vapor from GNSS Observations

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Ming Shangguan (Successful finalization March 2014)

Faculty VI - Planning Building Environment, Technical University Berlin

Water vapor in the atmosphere plays an important role in meteorological applications. The Global Navigation Satellite System (GNSS) provides accurate all-weather observations. The application of the existing GNSS infrastructure for atmosphere sounding leads to rather inexpensive and reliable measurements of the atmospheric water vapor. Observations from GNSS networks contain information about the spatial and temporal distribution of the water vapor.

The main objective of this thesis is to improve the water vapor tomography and to provide atmospheric water vapor products with good quality. A new tomographic algorithm based on a Kalman filter is added in the GFZ tomography system. The output is a 3D humidity field with a temporal resolution of 2.5 min and the error covariance matrix of the reconstructed states. more to: Analysis and Derivation of the Spatial and Temporal Distribution of Water Vapor from GNSS Observations

GPS Meteorology with Single Frequency Receivers

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Zhiguo Deng (Erfolgreiche Fertigstellung Juni 2012)

GFZ Potsdam

In this thesis it is shown that the epoch-differenced ionospheric delay correction is sufficient for estimating the tropospheric delay, e.g., the Zenith Total Delay (ZTD), from SF GPS data. Based on this result, the Satellite-specific Epoch-differenced Ionospheric Delay model (SEID) was developed. In the SEID model the ionospheric corrections for SF data are generated from the observations of surrounding reference stations equipped with DF receivers. more to: GPS Meteorology with Single Frequency Receivers

A Global Survey of Sporadic E Layers based on GPS Radio Occultations by CHAMP, GRACE and FORMOSAT–3 / COSMIC

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Christina Arras (Successful finalization April 2010)

Faculty of Physics and Earth Sciences, University Leipzig

The ionosphere is a part of the upper atmosphere stretching from a height of about 60 km to more than 1 000 km. A certain fraction of the gas particles in that region is ionised by solar extreme ultra violet radiation. Since electromagnetic waves are influenced and significantly modified by ionospheric free charge carriers, the altitude range is of great scientific interest. more to: A Global Survey of Sporadic E Layers based on GPS Radio Occultations by CHAMP, GRACE and FORMOSAT–3 / COSMIC

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