GS 873 Advanced Satellite Geodesy. Laboratory No. 2. April 8, Problem: Quantification of Satellite Orbit Errors Due to Gravity

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1 GS 873 Advanced Satellite Geodesy Laboratory No. 2 April 8, 2004 Instructor: C.K. Shum, ckshum@osu.edu Instructor Assistant: Shengjie Ge, ge.18@osu.edu Problem: Quantication of Satellite Orbit Errors Due to Gravity Compute near-earth orbit errors due to gravity covariance matrix, as a function of geographical locations (program geoper), geopotential order (program orderms), inclination (program satrms). The gravity eld covariance matrices include JGM3, TEG4, EGM96, OSU (2 versions), GRIM5C1, to 50x50. You are required to use only one covariance matrix, e.g., EGM96, however, feel free to use different covariance matrices so you could compare results with other students in the class. Questions: 1. The Gravity Recovery and Climate Experiment (GRACE) satellite mission (a system of two satellites on following the other) was launched in March 2002, to conduct mapping of time variable gravity eld signals ( Compute the radial orbit errors for GRACE (500 km, 89 0 inclination) due to geopotential based on one choice of the geopotential variance/covariance matrices1. Run orderms and satrms and geoper programs. Interpret the results using graphical aids. 2. The NASA and CNES radar altimeter satellite JASON-1 ( was launched December 7, 2001 to observe large-scale ocean circulation and sea level changes. Compute the radial orbits of JASON (1354 km, 66 0 inclination) due to geopotential error based on a choice of the geopotential variance/covariance matrices 1. Run orderms and satrms and geoper programs. For geoper results, note and explain the predicted mean, variable, and crossover (orbit) errors. Interpret the results using graphical aids. 3. The European Space Agency General Ocean Circulation Experiment (GOCE) mission will carry a spaceborne gradiometer for static gravity mapping and is scheduled to be launch in 2006 ( with a near circular orbit, 250 km altitude and inclination. Select a covariance matrix 1 among the above which would presumably the best prelaunch gravity eld and Run ordrms. What can you conclude from the result of the run? State all the assumptions. Notes: 1 Covariance matrices (EGM-96, JGM-3, EGM96, TEG-4, GRIM5C1, etc) are located at the OSC Cray SV1: /oscb.osu.edu/home/osu2545/schan/cov/model)

2 2 PMAX (in days) is a parameter input for the program. Interpret the meaning of this parameter and use it appropriately. References: Rosborough, G., Satellite orbit perturbations due to the geopotential, CSR-86-1, Center for Space Research, University of Texas at Austin, January Shum, C., B. Zhang, B. Schutz, and B. Tapley, Atlimeter crossover methods for precision orbit determination and the mapping of geophysical parameters, Jl of Astron. Sci., 38(3), , July-September, Scharro, Remko, A decade of ERS satellite orbits and altimetry, PhD Dissertation, Technical University of Delft, The Netherlands, Appendix: Computer information: IP: oscb.osc.edu (Cray SV1, see Run batch jobs ONLY. Make sure that you do not allocate a lot of time to run the job (they cause resources or money). Do NOT copy programs or les again to your home directory. Brief Tutorial Super-computer CRAY SV1 at Ohio Super Computer (OSC) Account information for the class: Unix machine using Secure Shell (SSH) Address: oscb.osc.edu Userid: osu3530 Password: <ask instructor assistant> Setup a directory using your last name, e.g., mkdir yourlastname Working in your own directories. More information about Unix and how to use CRAY SV1 Tutorial at: Basic UNIX Intermediate UNIX Batch Processing on OSC Systems Features of the SV1 at OSC OSC web: File locations /home/osu2545/schan/cov/model rw osu2545 G Feb 10 15:45 CV3RSO.50.COV rw-r osu2545 G Jul EGM96.50.COV

3 0 -rw osu2545 G Oct GRIM5C1.50.COV 0 -rw-r osu2545 G Jul JGM3.50.COV 0 -rw-r osu2545 G Jul TEG3.50.COV 0 -rw-r--r-- 1 osu2545 G Aug TG4C COV.new Program source code and script should be on S.J. Ge s account: /home/osu2541/ Sample Job Decks: a) SATRMS QSUB -s /bin/sh -eo -ro QSUB -r satrms QSUB -lt lm 8Mw set -xs change to temporary directory change to temporary directory set the name of the log le ID=`echo $QSUB_REQID sed 's/\..*$//'` LOG="${QSUB_WORKDIR}/${QSUB_REQNAME}.o${ID}" start accounting ja jacct$$ access any les you may need satellite='cryosat' gravity='egm96' gravity='teg3' gravity='jgm3' run program, A0, AF, initial and nal altitudes A0 = , AF = , DELTA = 10., ; STARLETTE ALTITUDE A0 = , AF = , DELTA = 10., ; AJISAI ALTITUDE A0 = , AF = , DELTA = 10., : ERS-1 ALTITUDE (35-DAY REPEAT) A0 = , AF = , DELTA = 10., ; GEOSAT ALTITUDE A0 = , AF = , DELTA = 10., ; ERS-1 ALTITUDE (3-DAY REPEAT) A0 = , AF = , DELTA = 10., ; TOPEX ALTITUDE A0 = , AF = , DELTA = 10., ; CRYOSAT (720km) satrms COV > OUTPUT << A0 = , AF = , DELTA = 10., RI0 = 1., RIF = 179., DELTI = 1., LONG = F, COVSCL = 1., PMAX = 5., ORDMIN = 0, ORDMAX = 50, rm COV close accounting

4 ja -csflht jacct$$ append log le to end of output and save in desired directory; log le will remain on original submission directory if any error occurs in copying log or saving output; output will also be in fortran carriage control form for printing if cp OUTPUT /c/osu2128/run_pro/satrms/satrms.$satellite.$gravity b) ORDRMS QSUB -s /bin/sh -eo -ro QSUB -r ordrms QSUB -lt lm 8Mw set -xs change to temporary directory change to temporary directory set the name of the log le ID=`echo $QSUB_REQID sed 's/\..*$//'` LOG="${QSUB_WORKDIR}/${QSUB_REQNAME}.o${ID}" start accounting ja jacct$$ access any les you may need satellite='cryosat' gravity='egm96' gravity='teg3' gravity='jgm3' run program A= ,INC=109.8 ; LAGEOS A= , INC=49.8, ; STARLETTE A= , INC=108.0, ; SEASAT/GEOSAT A= , INC=50.0, ; AJISAI A= , INC=98.55, ; ERS-1 (35-DAY REPEAT) A= , INC=115.0, ; GEOS-3 A= , INC=98.52, ; ERS-1 (3-DAY REPEAT) A= , INC=65.1, ; TOPEX A= , INC=92.0, ; CRYOSAT ordrms COV > OUTPUT << A = , INC = 92., LONG = F, PMAX = 5., COVSCL = 1., rm COV close accounting ja -csflht jacct$$

5 append log le to end of output and save in desired directory; log le will remain on original submission directory if any error occurs in copying log or saving output; output will also be in fortran carriage control form for printing if cp OUTPUT /c/osu2128/run_pro/ordrms/ordrms.$satellite.$gravity c) GEOPER run program geoper COV > OUTPUT << RA = , E = , RINC = 92.0, XLATMN = -88.0, XLATMX = 88.0, PMAX = 5.0, LONG =.FALSE., LMIN = 0, LMAX = 50, MMIN = 0, MMAX = 50, DLON = 3.0, DLAT = 3.0, PRADA =.F., PRADD =.F., PRADM =.T., PRADV =.T., PRADC =.F., RESID =.F., XOVER=.T., GLBRMS =.T., ALTMTR=.T., RMSRES =.F., TJD1 = , TJD2 = , RESTRT =.F., MEAN RADIAL ORBIT ERROR FOR $satellite PREDICTED BY $gravity GRAVITY COVARIANCE save les (other than OUTPUT) cp RADM /c/osu2128/run_pro/cpr/geoper.$satellite.$gravity.mean cp RADA /c/osu2128/run_pro/cpr/geoper.$satellite.$gravity.asc cp RADD /c/osu2128/run_pro/cpr/geoper.$satellite.$gravity.des cp RADV /c/osu2128/run_pro/cpr/geoper.$satellite.$gravity.var close accounting ja -csflht jacct$$ append log le to end of output and save in desired directory; log le will remain on original submission directory if any error occurs in copying log or saving output; output will also be in fortran carriage control form for printing if cp OUTPUT /c/osu2128/run_pro/cpr/geoper.$satellite.$gravity.cpr