Dramatic ice mass loss has been observed in West Antarctica using space gravimetry from the Gravity Recovery and Climate Experiment (GRACE) satellite mission, satellite altimeter data, and input-output methods (IOM). GRACE, satellite altimetry and IOM complement one another: GRACE provides a direct estimate of total mass change at fairly low resolution while the other two methods provide ice height variation or flux variation (IOM) at much higher spatial resolution. For satellite altimetry, an array of assumptions, with possible biases, may corrupt the conversion of ice height to mass change. Time-varying GRACE mass mapping is limited by the fact that it cannot provide the small-scale resolution that satellite altimetry provides, and it is difficult to isolate the exact location of a mass anomaly without introducing constraints. [more]
Climate studies require long data records extending the lifetime of a single remote sensing satellite mission. Precise satellite altimetry exploring global and regional evolution of the sea level has now completed a two decade data record. A consistent long-term data record can only be constructed from a sequence of different, partly overlapping altimeter systems by means of a careful cross-calibration.
At DGFI, satellite altimeter cross-calibrations are routinely performed with all available altimeter systems including mission phases from geodetic and drifting orbits. The methodology of this calibration is described in detail in a new Remote Sensing paper giving also selected results from the latest computation run.
The paper compiles – for the first time – a complete list of range biases between all relevant altimeter systems of the last 20 years, from ERS-1 to SARAL including less prominent missions such as GFO, ICESat, or HY-2A (cf. Table). Moreover, the computations provide time series of radial errors and allow to estimate empirical auto-covariance functions, systematic variations in the geo-centering of altimeter satellite orbits, as well as geographically correlated mean errors for all altimeter systems.
For more details see:
Bosch W., Dettmering D., Schwatke C.: Multi-Mission Cross-Calibration of Satellite Altimeters: Constructing a Long-Term Data Record for Global and Regional Sea Level Change Studies. Remote Sensing. 2014; 6(3):2255-2281 (available via open-access)
The Young Author Award 2012 of the International Association of Geodesy (IAG) was presented to DGFI scientist Dr. Manuela Seitz during the IAG Scientific Assembly 2013 in Potsdam for her paper “The 2008 DGFI Realization of the ITRS: DTRF2008” (DOI:10.1007/s00190-012-0567-2) that she published together with her colleagues from DGFI D. Angermann, M. Bloßfeld, H. Drewes and M. Gerstl.
With the Young Author Award IAG honors important publications of young authors in the Journal of Geodesy. The prize is granted at each IAG General or Scientific Assembly.
The award-winning paper deals with the realization of the International Terrestrial Reference System (ITRS) in the frame of DGFI's ITRS Combination Centre of the International Earth Rotation and Reference Systems Service (IERS). It explains in detail the computation strategy applied at DGFI and provides a comprehensive discussion of the results.