GSN QC at the IRIS DMC

Mary TempletonGSN Coordination Meeting

Seattle, WANovember 16, 2011

GSN QC at the DMC

• Began July 1, 2011• Looking to optimize 1/2 FTE• Charges so far

– Do what you do for US-REF– Extra attention to metadata– In situ response monitoring

Routine QC and Reporting

• Draft weekly report– In the internal feedback stage– Reference Network approach– report current problems to

network operators

Report Content

• Current and recently resolved outages• Real-time telemetry issues• Excessive gap list• Archive status of non-real-time

stations• Timing issues• Instrumentation or site issues• Metadata issues

Attention to Metadata• Location• Orientation• Instrument type

– Response– Instrument comment

• Sample rate– Channel (B052)– MiniSEED fixed section– Response high fc – Response cascade final sample rate

Metadata Consistency Checking

• Response checking– Evalresp

• SEED conformance• Sensitivity (fnorm in passband)• Units• FIR delays

– Visual inspection

Metadata Consistency Checking

• Do changes that correspond to epoch changes agree for all appropriate SNCLs?– Epoch start/end times– Sensor or datalogger sensitivity– Pole/zero or FIR cascade

In Situ Response Monitoring

• The problem: find a way to see frequency-dependent STS-1 response changes reported by the Waveform Quality Center at the DMC.

• “In situ” - monitoring methods not requiring remote or local instrument control.

Ideal Method(s)

• assess single, as well as coincident sensors

• apply to vertical and horizontal channels

• measure amplitude and phase errors

• periods from 2t to at least 250s

Ideal Method(s)• separate response issues from other

amplitude issues (noise, model limitations, hardware performance)– strong correlation or coherence for

synthetic or coincident sensor comparisons

– “known” signal for single-sensor techniques

• redundant measurements at period(s) of interest

Techniques in Use

Technique Sensors Channels Amp/Phase Periods

Earth Tide synthetics single Z (all?) both 44712s

Event synthetics (WQC) single all amplitude 2t-400s

Event cross-spectra coincident all both common passband

Microseism cross-specra coincident all both ~7s

PSD/PDF tools (DMC) single all amplitude 2t-172

0S0 normal modes single Z (all?) both 1227.52s

Recommendations

• Prototype cross-spectra of coincident sensors

Mw=6.9 Sikkim, India (9/18/11)Cross-spectra

Mw=6.9 Sikkim, India (9/18/11)Cross-spectra

Recommendations

• Prototype cross-spectra of coincident sensors

• Evaluate what it would take to incorporate Princeton synthetics comparison

Recommendations

• Prototype cross-spectra of coincident sensors

• Evaluate what it would take to incorporate Princeton synthetics comparison

• Add ocean loading to existing tidal synthetics at the DMC

Recommendations

• Prototype cross-spectra of coincident sensors

• Evaluate what it would take to incorporate Princeton synthetics comparison

• Add ocean loading to existing tidal synthetics at the DMC

• Calculate PSDs over period range appropriate to sensor passband

Recommendations

• Prototype cross-spectra of coincident sensors

• Evaluate what it would take to incorporate Princeton synthetics comparison

• Add ocean loading to existing tidal synthetics at the DMC

• Calculate PSDs over T range appropriate to sensor passband

• Make calculated traces available to users

Mw=6.9 Sikkim, India (9/18/11)Cross-spectra (Davis)