getTimeseries: Retrieve seismic data from IRIS DMC

In IRISSeismic: Classes and Methods for Seismic Data Analysis

Retrieve seismic data from IRIS DMC

Description

The getTimeseries method makes a request of the IRIS DMC timeseries webservice and returns a Stream object in which individual Traces have been sorted by start time.

Usage

getTimeseries(obj, network, station, location, channel, 
              starttime, endtime,...)

Arguments

obj	IrisClient object
network	character string with the two letter seismic network code
station	character string with the station code
location	character string with the location code
channel	character string with the three letter channel code
starttime	POSIXct class specifying the starttime (GMT)
endtime	POSIXct class specifying the endtime (GMT)
...	optional arguments repository optional character string identifying whether to exclusively search primary archive or realtime collection buffers. Acceptable values are "primary" or "realtime". If not specified, IRIS webservices defaults to both repositories. processingoptional character string with processing commands inclusiveEnd optional logical determining whether the endtime is inclusive (default = TRUE) ignoreEpoch optional logical defining behavior when multiple epochs are encountered (default = FALSE)

Details

This is an alternative method for retreiving seismic data that accepts optional processing commands. Data requests are made through the timeseries webservice and returned data are parsed using the internal miniseed2Stream() function.

If the location argument contains an empty string to specify a 'blank' location code, a location code of "--" will be used in the dataselect request URL.

The processing parameter can be used to specify any type of processing supported by the timeseries webs service. This string must begin with an ampersand and be ready to be appended to the request url, e.g. processing="&demean=true&taper0.2,HANNING". This gives the user complete control over the number and order of processing commands. (See timeseries documentation.)

If inclusiveEnd=FALSE, then getDataselect will subtract 0.000001 seconds from the endtime before passing the value to the dataselect webservice. An endtime of, e.g., as.POSIXct("2016-01-03", tz="GMT") will be passed into dataselect as end=2016-01-02T23:59:59.999999. A data sample at time 2016-01-03T00:00:00 will not be returned unless inclusiveEnd=TRUE.

Sometimes the station webservice will return multiple records for the same SNCL, each with a different scale or starttime. These represent different epochs with potentially different metadata parameters for the SNCL and, by default, will cause a 'Multiple epochs' error message to be generated.

Handling all possible metadata differences so that the data may be merged is beyond the scope of this package. Instead, to avoid errors, users may specify ignoreEpoch=TRUE in which case the very first SNCL-epoch encountered will be used and all others will be discarded.

For access to restricted data, getDataselect will look for system environmental variable "IrisClient_netrc" which should point to a .netrc authentication file.

Error returns from the webservice will stop evaluation and generate an error message.

Value

A new Stream object is returned.

Author(s)

Jonathan Callahan [e-mail]

References

The IRIS DMC timeseries webservice:

https://service.iris.edu/irisws/timeseries/1/

See Also

getDataselect, getSNCL, IrisClient-class

Examples

## Not run: 
# Open a connection to IRIS DMC webservices (use debug=TRUE so we can see the URLs generated)
iris <- new("IrisClient",debug=TRUE)

starttime <- as.POSIXct("2013-06-01",tz="GMT")
endtime <- starttime + 24*3600

# Get raw data and processed data
st1 <- getDataselect(iris,"IU","ANMO","00","LHZ",starttime,endtime)
st2 <- getTimeseries(iris,"IU","ANMO","00","LHZ",starttime,endtime,"&demean=true&taper=0.2,HANNING")

layout(matrix(seq(2)))
plot(st1)
plot(st2)

## End(Not run)

IRISSeismic documentation built on Oct. 16, 2022, 1:09 a.m.