VieVS User Workshop 14 – 21 September, 2011 Vienna Reprocessing the complete history of VLBI observations with VieVS Sigrid Böhm

Why should one do that? There are new solution methods/strategies. There is a new software. You would like to create a database with the optimal parameterization for each session. You are interested in time series of special parameters (such as ERP) covering the longest time span available. VieVS User Workshop 20112

TS of special parameters - EOP Which sessions to choose for processing? Define exclusion/suitability criteria No local or regional networks No sessions with < 3 stations (except for dUT1 determination from Intensives) No sessions with < 250 observations VieVS User Workshop 20113

Create a process list Basic list to start: e.g. use mk_list to get a list of intensive sessions, add this int_list to exclude.txt and then use mk_list with the option ‘ALL’ except ‘exclude.txt’. Use preliminary list and process all sessions with a basic parameterization Then you can use the data in LEVEL3 to make an extended exclude list according to the previously defined criteria and find sessions which are not working properly VieVS User Workshop 20114

Interesting parameters for the criteria and for “not working properly“ DATA/LEVEL3/SUBDIR/opt_sessname.mat: opt_.total_obs = number of observations length(opt_.stat) = number of stations opt_.mo = error of unit weight a posteriori opt_.cond = condition number of N-matrix (a bit difficult to judge) In Matlab: you can use diary(‘thisrun.log’) to store the output from the command window, diary off to stop the function VieVS User Workshop 20115

e.g. log-file: search for “RCOND” VieVS User Workshop 20116

check “geometry“ Take the information from the files stored in DATA/LEVEL1 and plot the network 7 Regional network → exclude the session

Other log-file “messages“ Problems with tidal ocean loading at station VLBA85 3 Problems with tidal atmosphere loading at station VLBA85 3 Problems with non-tidal atmosphere loading at station VLBA85 3 Problems with thermal correction at station VLBA85 3 Problems with VMF1 at station VLBA85 3 VieVS User Workshop 20108

For the remaining sessions with high  0 There is no other way than …  going through all of them individually finding clock breaks, bad stations etc. creating hundreds of OPT files Most welcome alternative … write a module for the automatic detection of clock breaks and creation of OPT files VieVS User Workshop 20119

Update process list Add all sessions you have sorted out to the „exclude“-file and run mk_list again Create an outlier file for each session with some simple parameterization Decide about your final parameterization according to your needs VieVS User Workshop

Some rules for EOP estimation Basic approach for daily resolution: Estimate all five EOP xp,yp,dUT1,dX,dY with 1440 min interval Estimate station coordinates and apply NNR, NNT conditions Polar motion with subdaily resolution: Do not estimate but fix nutation!! Fix station coordinates VieVS User Workshop

R1 and R4 networks VieVS User Workshop

VieVS User Workshop Comment on correlation coefficients The Matlab function corrcoef works correctly but not for our purpose. It does not take a covariance matrix as input! (Refer to Matlab Help for further info) Correlation coefficient: Qxx = inv(atpa_.mat); varii = diag(Qxx); Rxy = Qxx./sqrt(varii*varii');

5 EOP 24 hours, NNR/NNT VieVS User Workshop

3 ERP 1h, nut 24 h, coord fix VieVS User Workshop

3 ERP 1h, nut fix, NNR/NNT VieVS User Workshop

3 ERP 1h, nut fix, coord fix VieVS User Workshop