Thread: New contributed MUSTANG metric: gsn_timing

Dear MUSTANG Users,

We would like to announce a new contributed metric, gsn_timing, courtesy of the Albuquerque Seismic Laboratory (ASL). The goal of this metric is to document a consistent timing quality measurement for stations in the Global Seismographic Network (GSN) across the variety of digitizers used throughout the history of the GSN. The algorithm is:

1. For Quanterra Q330HR digitizers (post-2009): return the minimum daily value of miniSEED Blockette 1001 Field 3 timing quality values.

2. For Quanterra Q680 digitizers: in most cases, return the minimum daily value of miniSEED Blockette 1001 Field 3 timing quality values. There are special cases where additional timing quality information is known and used to modify the metric values to match what would be expected output from a Q330HR.

3. For older IRIS/IDA dataloggers: these did not record Blockette 1001. The metric value is calculated using the time of last clock lock and the drift rate in a manner that closely matches the Q330HR.

These gsn_timing measurements return values of 0-100%. A value of 60% or greater indicates good timing quality. A value of less than 60% identifies data that may need additional scrutiny before use in tasks that require precise timing. We now have measurements spanning 1995-present available through MUSTANG for GSN stations. For additional information, see http://service.iris.edu/mustang/metrics/docs/1/desc/gsn_timing/

Best Regards,
Gillian Sharer
IRIS DMC