C. (Christian) Siemes
C. (Christian) Siemes
Profile
Biography
I studied geodesy at the University of Bonn in Germany, where I received in April 2004 my diploma in engineering (Dipl.-Ing.) and an award from the German Association of Surveying (DVW – Deutscher Verein für Vermessungswesen) for good and fast studies. I stayed at the University of Bonn to conduct research in satellite geodesy. After obtaining my doctorate in April 2008, I moved to TU Delft to continue my research in satellite geodesy as a postdoctoral researcher. In January 2010, I started working as a research fellow for the European Space Agency at ESTEC in Noordwijk, the Netherlands. In November 2011, my research fellowship was transformed into a contractor position at the RHEA Group, where I continued to support the European Space Agency on the GOCE and Swarm missions and contributed to the development of future gravity mission concepts. In September 2019, I took on a new challenge as an assistant professor at TU Delft.
Expertise
Since the beginning of my doctorate, my research focused on satellite missions dedicated to measuring the gravity field of our planet. Models of the gravity field find applications in geodesy and allow the derivation of geostrophic ocean currents when augmented with satellite altimetry, giving crucial information on the heat transport from the tropics to artics. The GRACE mission is so sensitive that it detects minuscule changes in the gravity field over time caused by melting ice sheets, groundwater depletion, sea level rise, and many other geophysical phenomena. Due to my long involvement in the GOCE and Swarm missions, I gained extensive expertise in operational data processing, covering the full range from processing raw instrument measurements to deriving higher-level data products. I also supported flight operations by preparing satellite maneuvers to calibrate the onboard instruments and conceived methods for designing orbit constellations for future gravity field missions. I have always worked at the interface between science and the space industry, e.g. by coordinating data quality working groups, in which scientists and instrument providers work together to improve the quality of the data products that the European Space Agency publishes. Over the years, I evolved into a specialist in space accelerometers that can also be used for inferring thermosphere density and wind speed, which has been my research focus since I started at Delft University of Technology. Supported by an excellent team, I maintain the world's most complete database of high-resolution thermosphere density observations derived from precise accelerometer data.
Expertise
Publications
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2024
GRACE-FO radiation pressure modelling for accurate density and crosswind retrieval
N. A. Hładczuk / J. van den IJssel / T. Kodikara / C. Siemes / P. Visser
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2024
Uncertainty of thermosphere mass density observations derived from accelerometer and GNSS tracking data
C. Siemes / J.A.A. van den IJssel / P.N.A.M. Visser
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2023
A Survey of Current Operations-Ready Thermospheric Density Models for Drag Modeling in LEO Operations
W. Kent Tobiska / Marcin Pilinski / Sean L. Bruinsma / Eric Sutton / Delores Knipp / Vishnuu Mallik / Bhavi Jagatia / Mike Siegers / C. Siemes / More Authors
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2023
Comparison of Empirical and Theoretical Models of the Thermospheric Density Enhancement During the 3–4 February 2022 Geomagnetic Storm
Jianhui He / Elvira Astafyeva / Xinan Yue / Nicholas M. Pedatella / Dong Lin / Timothy J. Fuller-Rowell / Mariangel Fedrizzi / Eelco Doornbos / Christian Siemes / More Authors
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2023
Daedalus MASE (mission assessment through simulation exercise)
A toolset for analysis of in situ missions and for processing global circulation model outputs in the lower thermosphere-ionosphere
Theodore E. Sarris / Stelios Tourgaidis / Panagiotis Pirnaris / Dimitris Baloukidis / Konstantinos Papadakis / Eelco Doornbos / Christian Siemes / Pieter Visser / Jose van den Ijssel / More Authors -