Summary
This metric reports the total length of time in seconds of all data gaps encountered within the entire requested time period, calculated at query time. It calculates gaps in data availability based on information stored in the rapidly-accessible IRIS SEED and PH5 archive database indexes (ts_index), as returned by the service.iris.edu/fdsnws/availability and service.iris.edu/ph5ws/availability web services.
The ts_gap_length_total metric is currently a prototype that will eventually become a standard MUSTANG metric.
Uses
Data gaps can indicate problems with data transmission configuration or performance, power cycling or other equipment down time, or data loss after transmission. The metric can also be used to cull data that is not continuous enough for certain research applications.
Data Analyzed
Traces – one N.S.L.C (Network.Station.Location.Channel) per measurement
Window – from start time to the end time of the request
Data Source – IRIS miniSEED archive database time series index (ts_index)
SEED Channel Types – All Time Series Channels
Algorithm
- Assemble availability web service trace extents for the time duration on each matching N.S.L.C.
- Sum the data gaps in seconds for this period of time.
total_duration = end_time - start_time; ts_gap_length_total = sum[0..k](start[k+1] - end[k] - (1 / sample_rate[k]));
Metric Values Returned
value – total gap length expressed in seconds
target – the trace analyzed, labeled as N.S.L.C.Q (Network.Station.Location.Channel.Quality)
start – beginning of the date requested (UTC)
end – end of the date requested (UTC)
lddate – UTC date/time the measurement was made
Notes
If the user specified end date does not include hour:min:sec, then it defaults to 00:00:00.
