Roger Bowman

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Infrasound Data Holdings of the SMDC Monitoring
Research Program

• Roger Bowman
• National Science Foundation Infrasound Workshop
• Waikololoa, Hawaii
• July 24-25, 2003

The views and conclusions contained in this
document are those of the author and should not
be interpreted as representing official policies,
either express or implied of the U.S. Army Space
and Missile Defense Command or the U.S.
Government.
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Outline

• Infrasound network
• Infrasound waveform data availability
• Infrasound station descriptions
• Infrasound research database

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(No Transcript)
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Overview of Holdings
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1-Year View of Holdings
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1-Month View of Holdings
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Station Information

• Station maps
• Station description
• Station channel information

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Station Maps
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Station Regional Topographic Maps
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Sample Station Description IS55

• Location Windless Bight, Antarctica
• Latitude -77.7400
• Longitude 167.590
• Elevation 0.041 km
• Layout 8-element, inner triangle, outer pentagon
  Sensor Type Model-5 Differential microbarometer
  Sensor
• Vendor Chaparral Physics
• Optimal Frequency Range 0.05 to 2.8 Hz
• Average Inner-sensor Spacing (inside) 0.175 km
• Average Inner-sensor Spacing (outside) 1.487 km
  Filters
• High frequency filters installed on each sensor
• Operated by University of Alaska
• Notes Significant microbarom activity Mt Erebus
  volcano situated very close to array Centered
  pentagon design has array response with little
  aliasing

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Infrasound Research Database

• Contents
• Waveforms for Soviet nuclear explosions compiled
  by Maxwell Technologies
• Waveform collection of University of Alaska/
  ENSCO
• Nuclear explosions, volcanoes, earthquakes,
  mountain associated waves, auroral waves, gravity
  waves, etc.
• Waveforms for other infrasound signals compiled
  by SAIC
• Chemical explosions, bolides, space shuttle
  re-entries, etc.
• Synthetic waveforms
• Metadata about the waveforms

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Infrasound Database Events
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Summary

• With support from SMDC, SAIC provides
• Current waveform data
• Research waveform databases
• Station descriptive data
• SAIC plans to provide these data to the
  infrasound community in future years

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Infrasonic USArray
Rolling array of 400 infrasound stations!
4-sensor arrays with hose filters
1-sensor w/ or w/out hose filters
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Infrasonic Bigfoot Concept

• Use data channel(s) on seismic Bigfoot data
  loggers
• Mixed deployment of 4-element arrays and single
  stations
• Arrays allow signal coherence and azimuth
  estimation, but
• Arrays require larger investment (hardware,
  station footprint, installation time, data
  volume)
• Single-sensor stations provide coverage for
  investigating the spatial variability of high SNR
  signals in more detail
• Possible mixture 1 array for every 10 stations
• Could be adjusted to meet budget constraints or
  research objectives

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Infrasonic Bigfoot Constraints

• Ensure that it remains a piggy back to solid
  earth program
• So that it doesnt crumble under its own weight
• Share data logger with seismic channels
• Avoid cost of separate data logger (may require
  more channels than planned for seismic Bigfoot,
  however)
• Avoid costs of separate time standard (GPS)
• Avoid costs of managing separate data stream
• Limit array aperture to 100-200 m
• Avoid large footprint requiring extensive site
  selection procedures
• Avoid cost and OM for radio telemetry from array
  elements
• Maintain modest sampling rate (20-40 Hz?)
• Avoid infrasonic data volumes that become
  significant relative to seismic data, but
• Dont throw the baby out with the bath water