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Station Metadata:What do I Need? Dr. Mary Templeton IRIS Data Management Center Data Management Workshop Bogotá, Colombia July 2014
Why is Metadata Important? • To use data, you need to know where and how it was recorded: • x,y,z,t • How do you translate the time series to ground motion? • Direction • Amplitude scaling • Phase shifting • The data format must be understood • Metadata is easiest to record before it’s forgotten
Steps for Building Metadata • Register your network and station names • Create a dataless SEED volume • Enter network information • Enter information for a single station • Add additional stations using the first as a “clone”
What do I Need? • Network information • FDSN network code • Network name • Operating institution
What do I Need? • Station information • Registered station code • Station long name • Location of the station and it’s sensors • Latitude (degrees from -90 to +90) • Longitude (degrees from -180 to +180) • Elevation (ground surface and sensor in m) • Depth (surface elevation – sensor elevation in m)
What do I Need? • Station information • Sensor channel orientations • Angle from geographic north to each horizontal channel (degrees from 0 to 360) • Sensor wiring convention • Normal: upward ground motion produces a positive Z amplitude (similar for N and E) • Reverse: upward ground motion produces a negative Z amplitude (industry geophones)
What do I Need? • Station information • Sample rates • Sensor long-period corner • Sensor gain
What do I Need? • Station information • Instrument response • Sensor • Sensitivity • Poles and zeros • A0 normalization factor • Datalogger • Preamplifier gain • Bit weight (A/D scale factor) • FIR coefficients for your field acquisition settings • other
What do I Need? • Station information • Optional • Text description of instrumentation • Instrument serial numbers • Comments documenting timing and other data problems
What do I Need? • And Finally…. • Time span (epoch) for which this information is valid • If any of this metadata changes, a new epoch need to be created with updated metadata • Epochs must not overlap in time
About Instrument Responses • The bad news • This is can be the most difficult part of gathering station metadata • The good news • We’ve created a response library to make this easier • More about this after the break!