For the first time, DGFI realizes the International Terrestrial Reference System (ITRS) and the International Celestial Reference System (ICRS) together with the Earth Orientation Parameters, which allow for a transformation between both systems, consistently in one adjustment. So far, ITRS and ICRS are realized independently at different computation centres.

In our computation, we considered data of Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR) and Global Navigation Satellite Systems (GNSS). The parameter considered in the realization are station coordinates, quasar coordinates and the EOP, i.e. the coordinates of the terrestrial and the celestial pole (polar motion and nutation) and UT1-UTC and their derivation in time. Alltogether about 45,000 parameters are solved. The results are presented at different international conferences and first results are already published [more].

ESA's gravity mission GOCE measures the Earth's mean gravitational field with unprecedented accuracy with a spatial resolution of 100 km or better. Comparing GOCE gravity gradients with gradients from geophysical modelling for the North-East Atlantic (NEA) margin shows that the spatial patterns are similar, but that the amplitudes differs. This indicates that even in well-surveyed areas, such as the NEA, GOCE data may contribute to improved modelling of the Earth's interior. [more]

Combining the most recent GOCE gravity fields and multi-mission satellite altimetry allow for the first time to estimate meso-scale features of the dynamic ocean topography (DOT). The “profile method” of DGFI even generates DOT profiles on individual ground tracks of any altimeter satellite which can be subsequently  gridded  to construct  (e.g. with 10 day sampling) a DOT time series spanning the period 1993 up to now. The animation shows the geostrophic velocity field of this time series for the South Atlantic and the Agulhas Counter Current with intensive Eddy formation. [more…]

Multi-mission altimetry processing at DGFI has demonstrated the potential to provide a complete mapping of baroclinic tides (due to internal waves with density variations). With some 100-150 km the wavelength of baroclinic tides are much shorter than for barotropic tides. Moreover, the baroclinic surface signal remains small (~ 2-5 cm amplitude), although the internal waves may reach amplitudes of several tens of meters. The figure shows the amplitudes of the M2 baroclinic tide … [more]

The first data of Cryosat-2, an altimeter mission primarily dedicated to ice observations, has now been included in DGFI’s multi-mission crossover calibration (MMXO). The analysis reveals a good quality of Level 2 Low Resolution Mode (LRM) data, a global mean range bias of about -0.59 m and a timing error of app. 11 ms. With 2.6 cm RMS of the radial errors, the data quality is very promising but not yet comparable to Jason and Envisat missions. [more]

On October 28, 2010 a contract was signed for the establishment of the Centre for Geodetic Earth System Research (CGE) in Munich. DGFI, the division Geodesy of the BAdW Commission on Geodesy and Glaciology (KEG), the Institute for Astronomical and Physical Geodesy (IAPG) and the Research Establishment for Satellite Geodesy (FESG) of TUM integrate their research in one common CGE programme. The principal objectives are investigations on global change by measuring variations in the solid Earth, oceans, ice covers and atmosphere, and analysing those variations with respect to the generating physical processes. [More]

To estimate the impact of the Chile earthquake in the Reference Frame for the Americas (SIRGAS), the SIRGAS Analysis Centre at DGFI estimated daily station positions between February 21 and March 6, 2010, for selected continuously operating SIRGAS stations. Results show that the GPS station CONZ (Concepción, Chile) initially moved 2,9 m in the south-west direction (on 27-02-2010). In the week following the first earthquake, post-seismic movements of more than 10 cm were detected. Additional GPS stations located between latitudes 30°S to 40°S from the Pacific to the Atlantic coast also present larger displacements. [More]

The free oscillations of the Earth caused by the displacement from the position of rest will be excited by earthquakes with a magnitude larger than 6.5 on the momentum scale. After the huge Offshore Maule earthquake in Chile on Februar 27, 2010 with magnitude 8.8 on the momentum scale the free oscillations were excited.

The frequency domain of free oscillations is between 0.3 mHz, i.e. a period of 54 minutes and 20mHz i.e. a period of 50 seconds. [More]

DGFI as one of the ITRS Combination Centres of International Earth Rotation and Reference System Service (IERS) has completed the computation of the International Terrestrial Reference Frame 2008 (DTRF2008). DTRF2008 is an independent solution, based on the same input data as ITRF2008, which is computed by the IERS Combination Centre at IGN, Paris, and provided by the IERS Product Centre at IGN in May 2010. The difference between both solutions is the combination strategy: while a combination of solutions is performed at IGN, DGFI computation is based on the combination of normal equations.

The DTRF2008 is a global terrestrial reference frame containing the station coordinates of 559 GPS, 106 VLBI, 122 SLR and 132 DORIS stations. The reference epoch for station positions is 2005-01-01, 0:00 UTC. Earth orientation parameters (EOP), i.e., coordinates of the terrestrial and the celestial pole, UT1-UTC and length of day (LOD), are simultaneously solved with the station coordinates. The time series of EOP covers the period from 1983 until the end of 2008. The solution is available in different file formats at ftp.dgfi.badw.de/pub/DTRF2008. A short description of the solution is given in the local SINEX file.