Summary
This metric cross-correlates a barometer and vertical seismic channel from the same station and reports the zero-lag correlation coefficient.
Uses
For stations with a zero-lag correlation coefficient near one, data quality may be improved by correcting the seismic traces for atmospheric pressure changes (Beauduin, et al., 1996).
Measurements for this metric only exist if a station has both LH and LDO channels, so using this metric as a constraint in an rrds request would only make sense if you wanted to eliminate stations without these two channels.
Beauduin et al (1996), The Effects of the Atmospheric Pressure Changes on Seismic Signals or How to Improve the Quality of a Station; BSSA v. 86, no. 6, pp 1760-1769.
Data Analyzed
Traces – two N.S.L.C (Network.Station.Location.Channel) per measurement where the two Channels are LDO and LH? from the same Station
Window – 24 hours starting at 00:00:00 UTC
Data Source – IRIS miniSEED archive or IRIS PH5 archive
SEED Channel Types – LDO:LH? | Pressure:High Gain
Algorithm
- Request 24 hours of available LDO and LH? time series
- For each station having both LDO and LH? channels,
- Cross-correlate the channel pair time series,
- Report the value of the correlation function at zero lag:
Rxy = (1/N) * sum( x(n)*y(n) ) where N = # of samples and n = 1…N
Metric Values Returned
value – correlation coefficient (cross-correlation function value at zero lag)
target – the two traces analyzed, labeled as N.S.L.LDO:LH?.Q (Network.Station.Location.Channel.Quality)
start – beginning of the data day requested (00:00:00 UTC)
end – end of the data day requested (truncated as 23:59:59 UTC)
lddate – date/time the measurement was made and loaded into the MUSTANG database (UTC)
