Using GLOBK and its Associated Programs

1. Using GLOBK and its Associated Programs

2. OVERVIEW • Basic types of analyses with globk • Velocity and repeatability runs • Programs in the GLOBK suite • htoglb • globk • glred • glist • glsave • hfupd • glbtosnx GAMIT/GLOBK Tutorial 8

3. Basic types of globk analyses • Generally globk is used in two ways: • Combining many years of data to generate velocities solutions • Analyzing groups of individual experiments to assess position quality • For example: • After many years of processing, coordinate systems are likely to change (eg., ITRF94 to ITRF2000) and globk can bring all early results into a consistent frame • Reason we write "loose" hfiles from gamit GAMIT/GLOBK Tutorial 8

4. Create a .gdl file • A gdl file is created by making a list of binary-hfiles. If running from directory gsoln, then ls ../glbf/h*.glx > india.gdl • (.glr files are bias free solutions, .glx are bias fixed. Sinex files are .gls) GAMIT/GLOBK Tutorial 8

5. Globk velocity command file • If multiple years of data, then try velocity solution • globk command file must include • apr_neu all 10 10 10 1 1 1 • where the 1 1 1 is velocity uncertainties in m/yr • If velocity relative to specific site then add • apr_neu iisc_gps 0.01 0.01 0.01 F F F • would fix velocity of iisc • Usually do not do this, but rather use glorg for generalized definition GAMIT/GLOBK Tutorial 8

6. glred • To check the quality of the individual positions in the hfiles we could create gdl files with just single hfiles listed and run globk on each one using a command file with • apr_neu all 10 10 10 0 0 0 • apr_neu iisc_gps 0.01 0.01 0.01 0 0 0 • Again iisc is constrained and normal process • Running globk on a set of individual hfiles is tedious so we have a program that automatically does this: glred GAMIT/GLOBK Tutorial 8

7. glred • glred is run the same way as globk ie. • glred <crt> <prt> <log> <gdl file> <command file> • but rather than combining all the data in the gdl files, each file is processed separately by globk • glred is a convenient way of making multiple globk runs GAMIT/GLOBK Tutorial 8

8. General format of gdl files • General format of a gdl file is: • [binary hfile name] <scale> <diagonal scale> <+> • all except the file name are optional • scale is a multiplier applied to the covariance matrix • diagonal scale scales the diagonal (only used for poorly conditioned sinex files) GAMIT/GLOBK Tutorial 8

9. glred gdl file • There are some options in the gdl file that add flexibility to glred • a + can be added at the ends of hfile name names so that groups of hfiles will be combined eg. • ../glbf/h991001_gps1.glx + • ../glbf/h991002_gps1.glx • ../glbf/h000601_gps1.glx + • ../glbf/h000602_gps1.glx • Would combine the first and second and third and fourth files. GAMIT/GLOBK Tutorial 8

10. glist • To determine what is contained in a set of binary files use glist • glist <gdl file> <output_file> <sort_direction> [eq_file] [out gdl] [apr file] • Only first argument required • adding eq_file will apply earthquakes and renames • out_gdl is a time sorted gdl file which can be used in globk • apr_file is an optional apr_file which the apr positions in the binary hfiles will be compared to. Differences greater than 0.3 m are reported. GAMIT/GLOBK Tutorial 8

11. glist • During tutorial we will use this program to check contents of local hfiles • A grep 'P$' will extract a list of positions of the sites and the duration of their use GAMIT/GLOBK Tutorial 8

12. glist • Allows solutions generated by globk to be saved as binary hfiles • Normally invoked in globk command file with the • out_glb <name/structure> • where name/structure is either: • Expliciit name of file • wild card constructor: Forms • H@.GLX will use the gdl file name replacing the first letter and extent • H------_SIO.GLX will use the 2-7 characters from the gdl file name GAMIT/GLOBK Tutorial 8

13. glsave • if the com_file command was used in globk, then glsave can be run as separate program • glsave <com file> [out global name] [description] <sol_file name> • where com file is the name of the file given in com_file command in globk • out global name is name for output binary hfile • description is string description enclosed in ' ' GAMIT/GLOBK Tutorial 8

14. glsave sol_file • sol file name is an optional new solution file (not usually used) • Generated in glorg where the glorg solution file can be output • For example: with coordinate system definition applied and constraints on nearby sites • Advanced feature which should be carefully used. GAMIT/GLOBK Tutorial 8

15. hfupd • hfupd allow updates to be made to the binary hfile files • hfupd <options> <list of hfile names> • Options include: • -s <sinex file/station.info> name of new station.info or sinex header file that contains new information about sites (eg. correct antenna height) • -e <edit file> file containing edited and renamed sites GAMIT/GLOBK Tutorial 8

16. hfupd options • -r report contents of station.info/sinex file • -u update the hfiles (must given to actually update files, without this option program reports changes to be made but does change files) • -p <hf/pmu_file> applied pole tide correction if needed. uses either polar motion values in hfile or in pmu_file • other options are advanced features GAMIT/GLOBK Tutorial 8

17. hfupd edit file • Edit file contains lines of form • EDIT <NAME> <HF code> <Epoch range> • deletes site NAME in hfile containing <HF code> in name for period given by epoch range • RESTORE <NAME> <HF code> <Epoch range> • will restore a site provided not a combined binary file GAMIT/GLOBK Tutorial 8

18. hfupd edit file • RENAME <OLD NAME> <NEW NAME> <HF code> <Epoch range> • will rename a site from OLD to NEW • Epoch range in form start (yr, mth, day, hr, min) end (yr, mth, day, hr, min) • start must before start of data in hfile and end must after end of data in hfile GAMIT/GLOBK Tutorial 8

19. glbtosnx • SINEX (Solution independent exchange format) is international standard for exchanging solutions of the types contained in binary hfiles • glbtosnx <dir> [-h] <comments file> <input binary hfile> <output file name> • dir is directory for name • -h will write only headers and not full covariance matrix • comments files is file containing comments (see $HELP_DIR/head.snx • output file name controls structure of generated file name GAMIT/GLOBK Tutorial 8

20. General items • Using ' ' for an input will often use a default value • Called a place holder when specific input required • glist file.gdl file.glist '' '' out.gdl • will use default sort direction (+1) and no earthquake file GAMIT/GLOBK Tutorial 8

21. Creating apr_file • apr_files are supplied in gg/templates • They can be created from globk output with • grep '^Unc. ' <prt/org file> | awk '{print substr($0,5)}' >! new.apr • Satellite ephemerides can be obtained with grep '^Eph. ' • Programs plate and corcom can also be used to generate apr files GAMIT/GLOBK Tutorial 8

22. Summary • Examined basic types of globk runs • The external programs used with globk to • List the contents of h-files • Save combined h-files • Run separate globk analyses • Update hfiles with new information • Convert h-files to SINEX files GAMIT/GLOBK Tutorial 8