Radio occultation at GFZ Potsdam: Current status and future prospects

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1 Radio occultation at GFZ Potsdam: Current status and future prospects J. Wickert, T. Schmidt, G. Beyerle, S. Heise, R. Stosius GFZ German Research Centre for Geosciences, Potsdam, Germany The CHAMP, GRACE, TerraSAR X team

2 Overview Status of current RO missions at GFZ Potsdam: CHAMP, GRACE and TerraSAR X Upcoming missions: Tandem X Future prospects: MicroGEM, ACES, HALO Summary

3 GPS radio occultation experiments CHAMP since 2006 since 2006 COSMIC/FORMOSAT 3 GRACE since 2008 MetOp since 2006 TerraSAR X

4 Current missions i at GFZ

5 Post processing at GFZ Post processing CHAMP: GRACE: DDIFF Version 5 reactivation? ZDIFF Version 6 TerraSAR X: SDIFF experimental Reprocessing project started

6 NRT processing at GFZ NRT processing Experimental start with CHAMP in 2006 Operational since mid 2007 with CHAMP and GRACE Bufr feeding to GTS via German Weather Service TerraSAR X raw data available, test data set for NWP centers provided

7 Data receiving for NRT processing 2 GFZ antennas in Ny Alesund, Spitsbergen

8 Impact of RO data: CHAMP vs. ECMWF DJF MAM JJA SON (a) (b) (c) (d) 2005 (e) (f) (g) (h) 2006 (i) (j) (k) (l) 2007 (from Schmidt et al., Ann. Geophysicae, 2008)

9 TerraSAR X technical data Technical data launch date 15 June 2007 launch site Baikonur, Kasakhstan orbit altitude 514 km orbit inclination 97.4 o dimension so 4.9 m x 2.4 m (diam.) mass 1230 kg design life time 5 years Instrumentation X band synthetic aperture radar (SAR) laser communication terminal TOR (retroreflector array and GPS receiver IGOR )

10 TerraSAR X technical data 48 channel GPS receiver IGOR GPS receiver IGOR 4 element antenna array 2 occultation antennas (forward and aft looking), tilted by 20 o towards horizon Improvements over CHAMP / GRACE : antenna array (4 elements) firmware modifications open loop tracking

11 TerraSAR X data processing and statistics (I) Experimental processing system (POCS X) precise GPS and TerraSAR X orbits from GFZ corrections: antenna phase center offsets, relativity, carrier phase wind up, clock biases demodulation of navigation data using independent observations extracted from NavBit data base bending angle initialization above 35 km using MSIS climatology wave optics (Full Spectrum Inversion / Canonical Transform) Statistics (24 July 17 November 2008) (rising occultations forward looking antenna not yet activated) number of events 26, % missing NavBit data % gaps in 0.1 Hz data % range incomplete ( 10 to +60 km SLTA) % ref. GPS below 10 o elevation % other % processed events 18,647 70%

12 TerraSAR X data processing and statistics (II) TerraSAR SAR(POCS X) single differencing, setting occultations, open loop tracking below 6 7 km 50% altitude: 980 m CHAMP (POCS) double differencing, setting occultations, fly wheeling tracking 50% altitude: 3.4 km Doubling of the data a rate aein the lower troposphere e GRACE A (POCS) zero differencing, setting occultations, fly wheeling tracking 50% altitude: 3.3 km

13 Upcoming mission i

14 TanDEM X Occ. antenna Start in December 2009 IGOR

15 TerraSAR X and TanDEM X Two identical German radar satellites, stereo view of the Earth Source: DLR and EADS

16 Future prospects

17 MicroGEM: Microsatellite for GNSS Earth Monitoring Phase A feasibility study: Minisatellite for Galileo POD: GNSS POD: SLR POD: VLBI Topside Ionosphere Tomography Reflectometry Ocean/Ice with Galileo/GPS Occultation Atmosphere/Ionosphere

18 MicroGEM: Microsatellite for GNSS Earth Monitoring 18 Sep 2009: Final presentation of Phase A study with Technical University Berlin, GFZ and regional industry.

19 Precise orbit determination GPS/Galileo, VLBI, SLR MicroGEM: Scientific goals Atmosphere/ionosphere sounding radio occultation and tomography Coherent reflectometry over water and ice proof of concept, initial demonstration Focus on initial application of Galileo signals for space based GNSS remote sensing Near polar orbit (~700 km altitude), piggy back pggy launch ~2012/13 planned Cost effective mission realisation

20 MicroGEM: Scientific payload GPS/Galileo SLR (Pyxis) (Satellite Laser Ranging) g) 3 geodetic POD methods on one satellite VLBI (Very Long Baseline Interferometry) transmitter

21 ACES: Atomic Clock Ensemble in Space Proposalto ESA: GALILEO on board theiss by Volume: 1172x867x1246 mm 3 Total mass: 227 kg Power: 450 W D. Svehla D, M. Rothacher, C. Salomon, G. Beyerle, J. Wickert, A. Helm, M. Ziebart, J. Dow, L. Cacciapuoti, T. Börner, A. Rius, E. Cardellach, O. Montenbruck, R. Rivas,T. Gruber, C. K. Shum Scientific Objectives - Geodesy Precise orbit determination for the ISS GPS/GALILEO time and frequency transfer combined with ACES MW link First demonstration of relativistic geodesy GPS/GALILEO coherent reflectometry/radio occultation (GNSS R/RO) GPS/GALILEO incoherent reflectometry/scatterometry (GNSS R) First demonstration of a tsunami early warning concept from the LEO orbit First demonstration of digital beamforming for wide swath GNSS R from the LEO orbit Combination of GNSS altimetry and conventional nadir altimetry

22 HALO The High Altitude and LOng Range Research Aircraft Reflectometry/Scatterometry Occultations Planned for 2011, GEOHALO (+ airborne gravimetry) For further questions contact Georg Beyerle:

23 Summary Status information: CHAMP (reactivation of ROs?), GRACE (NRT and PP), TerraSAR X, Tandem X (start very soon) Reprocessing of all CHAMP/GRACE data from Level 0 Future missions: MicroGEM (Jens Wickert, wickert@gfz potsdam.de) de) ACES (ESA proposal: GALILEO on board the ISS ) HALO (Georg Beyerle,,gbeyerle@gfz potsdam.de)