A corrective model for Jason-1 DORIS Doppler data in relation to the South Atlantic Anomaly

The DORIS Doppler measurements collected by Jason-1 are abnormally perturbed by the influence of the South Atlantic Anomaly (SAA). The DORIS ultra-stable oscillators on-board Jason-1 are not as stable as they should be; their frequency is sensitive both to the irradiation rate and to the total irradiation encountered in orbit. The consequence is that not only are the DORIS measurement residuals higher than they ought to be, but also large systematic positioning errors are introduced for stations located in the vicinity of the SAA. In this paper, we present a method that has been devised to obtain a continuous observation of Jason-1 frequency offsets. This method relies on the precise determination of the station frequency and troposphere parameters via the use of other DORIS satellites. More than 3 years of these observations have then been used to construct a model of response of the oscillators of Jason-1 to the SAA. The sensitivity of the Jason-1 oscillators to the SAA perturbations has evolved over time, multiplied by a factor of four between launch and mid-2004. The corrective performances of the model are discussed in terms of DORIS measurement residuals, precise orbit determination and station positioning. The average DORIS measurement residuals are decreased by more than 7 % using this model. In terms of precise orbit determination, the 3D DORIS-only orbit error decreases from 5 to 4.2 cm, but the DORIS+SLR orbit error is almost unaffected, due to the already good quality of this type of orbit. In terms of station positioning, the model brings down the average 3D mono-satellite monthly network solution discrepancy with the International Terrestrial Reference Frame ITRF2000 from 11.3 to 6.1 cm, and also decreases the scatter about that average from 11.3 to 3.7 cm. The conclusion is that, with this model, it is possible to re-incorporate Jason-1 in the multi-satellite geodetic solutions for the DORIS station network.

[1]  David J. Diner,et al.  Performance of the MISR instrument during its first 20 months in Earth orbit , 2002, IEEE Trans. Geosci. Remote. Sens..

[2]  Bernard Pinty,et al.  Multi-angle Imaging SpectroRadiometer (MISR) instrument description and experiment overview , 1998, IEEE Trans. Geosci. Remote. Sens..

[3]  Gilles Tavernier,et al.  The current evolutions of the DORIS system , 2003 .

[4]  V. Candelier,et al.  Space qualified 5 MHz ultra stable oscillators , 2003, IEEE International Frequency Control Symposium and PDA Exhibition Jointly with the 17th European Frequency and Time Forum, 2003. Proceedings of the 2003.

[5]  Dudley B. Chelton,et al.  The Accuracies of Smoothed Sea Surface Height Fields Constructed from Tandem Satellite Altimeter Datasets , 2003 .

[6]  S. L. Huston,et al.  Space Environment Effects: Low-Altitude Trapped Radiation Model , 1998 .

[7]  D. Heynderickx,et al.  Comparison between methods to compensate for the secular motion of the South Atlantic anomaly , 1996 .

[8]  Joseph Lemaire,et al.  Historical review of the different procedures used to compute the L-parameter , 1996 .

[9]  Jan Vondrák,et al.  Combined smoothing method and its use in combining Earth orientation parameters measured by space techniques , 2000 .

[10]  B. L. Colborn,et al.  Predictions of induced radioactivity for spacecraft in low Earth orbit , 1992 .

[11]  John C. Ries,et al.  The International Doris Service (IDS) , 2004 .

[12]  E. J. Christensen,et al.  TOPEX/POSEIDON mission overview , 1994 .

[13]  Ronald J. Muellerschoen,et al.  Topex/Jason combined GPS/DORIS orbit determination in the tandem phase , 2003 .

[14]  P. Willis,et al.  Defining a DORIS core network for Jason-1 precise orbit determination based on ITRF2000: methods and realization , 2005 .

[15]  Bruce J. Haines,et al.  The Jason-1 Mission Special Issue: Jason-1 Calibration/Validation , 2003 .

[16]  Antony C. Fraser-Smith,et al.  Centered and eccentric geomagnetic dipoles and their poles, 1600–1985 , 1987 .

[17]  Hervé Fagard,et al.  Twenty years of evolution for the DORIS permanent network: from its initial deployment to its renovation , 2006 .

[18]  G. Badhwar,et al.  Effects of trapped proton flux anisotropy on dose rates in low Earth orbit. , 1999, Radiation measurements.

[19]  James I. Vette,et al.  The NASA/National Space Science Data Center trapped radiation environment model program, 1964 - 1991 , 1991 .

[20]  John C. Ries,et al.  Jason-1 Precision Orbit Determination by Combining SLR and DORIS with GPS Tracking Data , 2004 .

[21]  Zuheir Altamimi,et al.  ITRF2000: A new release of the International Terrestrial Reference Frame for earth science applications , 2002 .

[22]  J. P. Berthias,et al.  Comportement de l'oscillateur DORIS/Jason au passage de l'anomalie sud-atlantique , 2004 .

[23]  P. Deschamps,et al.  DORIS (Doppler orbitography and radiopositioning integrated from space): System assessment results with DORIS on SPOT 2 , 1990 .

[24]  Pascal Willis,et al.  The International DORIS Service , 2005 .