Using GLOBK and its Associated Programs GAMITGLOBK Tutorial

Using GLOBK and its Associated Programs GAMIT/GLOBK Tutorial 8

OVERVIEW • Basic types of analyses with globk – Velocity and repeatability runs • Programs in the GLOBK suite – htoglb – globk – glred – glist – glsave – hfupd – glbtosnx 10/31/2020 GAMIT/GLOBK Tutorial 8 2

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. , ITRF 94 to ITRF 2000) and globk can bring all early results into a consistent frame • Reason we write "loose" hfiles from gamit 10/31/2020 GAMIT/GLOBK Tutorial 8 3

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) 10/31/2020 GAMIT/GLOBK Tutorial 8 4

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 F F F – would fix velocity of iisc – Usually do not do this, but rather use glorg for generalized definition 10/31/2020 GAMIT/GLOBK Tutorial 8 5

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 • apr_neu iisc_gps 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 10/31/2020 GAMIT/GLOBK Tutorial 8 6

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 10/31/2020 GAMIT/GLOBK Tutorial 8 7

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 scales the diagonal (only used for poorly conditioned sinex files) 10/31/2020 GAMIT/GLOBK Tutorial 8 8

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 names so that groups of hfiles will be combined eg. • • . . /glbf/h 991001_gps 1. glx +. . /glbf/h 991002_gps 1. glx. . /glbf/h 000601_gps 1. glx +. . /glbf/h 000602_gps 1. glx • Would combine the first and second and third and fourth files. 10/31/2020 GAMIT/GLOBK Tutorial 8 9

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. 10/31/2020 GAMIT/GLOBK Tutorial 8 10

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 10/31/2020 GAMIT/GLOBK Tutorial 8 11

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 10/31/2020 GAMIT/GLOBK Tutorial 8 12

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 ' ' 10/31/2020 GAMIT/GLOBK Tutorial 8 13

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. 10/31/2020 GAMIT/GLOBK Tutorial 8 14

hfupd • • hfupd allow updates to be made to the binary hfiles 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 10/31/2020 GAMIT/GLOBK Tutorial 8 15

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 10/31/2020 GAMIT/GLOBK Tutorial 8 16

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 10/31/2020 GAMIT/GLOBK Tutorial 8 17

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 10/31/2020 GAMIT/GLOBK Tutorial 8 18

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 10/31/2020 GAMIT/GLOBK Tutorial 8 19

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 10/31/2020 GAMIT/GLOBK Tutorial 8 20

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 10/31/2020 GAMIT/GLOBK Tutorial 8 21

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 10/31/2020 GAMIT/GLOBK Tutorial 8 22