National Center for Physical Acoustics

University of Mississippi

News & Research Highlights

Tornado Detection

tornado-detection

The National Center for Physical Acoustics (NCPA) at the University of Mississippi is conducting research to detect and monitor severe storms under NOAA Specific Cooperative Agreement NA08NWS4680044. NCPA collected and analyzed infrasound data that points to a possible capability for advanced warning and accurate tracking of tornados.  Analysis of data collected during a tornado outbreak in central Oklahoma on May 24, 2011 indicates that two field-deployed infrasound arrays detected and tracked three tornadoes.  The infrasound signals were quite large and distinct, indicating that detections at significantly larger ranges would have been possible.  A network of infrasound arrays deployed through a region could provide the weather services with detections and tracks of tornadoes throughout the region. Given that it takes about 3 minutes for sound to travel from a tornado to an array 40 miles away, it is conceivable that warnings could be issues within tens of minutes.

Bearings from the infrasound arrays to the Stillwater (left) and Chickasha–Blanchard-Newcastle tornados as determined from the infrasound data. Generally good agreement with the known position and track of the tornado was obtained. Similar results were obtained for the Calumet-El Reno-Piedmont–Guthrie storm.

 

Hurricane Monitoring

hurricane-monitoring

The infrasound group at the National Center for Physical Acoustics (NCPA) at the University of Mississippi has been investigating the use of the microbarom signal to probe the interior of hurricanes.  Microbaroms are infrasonic signals produced by the collision of counter-propagating ocean waves of equal periods.  These signals are routinely detected thousands of kilometers from their source.  Hurricanes are known to be a large source of microbarom radiation. Researchers at the NCPA have shown that the source of microbaroms from hurricanes is the collision of waves produced by the storm with the background ocean swell. The region where these collisions occur tends to be hundreds of kilometers south of the eye of the storm.

NCPA deployed infrasound arrays along the eastern seaboard for the 2010, 2011, and 2012 hurricane seasons to test the idea that the microbarom signal can be severely refracted by the storm winds, providing a possible tool for the determination of these winds. It was demonstrated conclusively that such severe refraction occurs and is a robust effect. If the hurricane is observed from the south, the microbarom signal reaches the array without passing through the storm along a straight line from the source to the receiving array. In this case, the back azimuth determined at the array points directly towards the microbarom source region. If the hurricane is observed from the north, the microbarom signal passes through the storm before reaching the receiving array and undergoes severe refraction. In this case, the back azimuth determined at the array does not point towards the microbarom source region. NCPA proposes to use the refraction of the microbarom signal by the hurricane to monitor the interior of the hurricane and to determine intensity. Hurricane intensity would be determined continuously and remotely. The time required for the signal to propagate to the array and for the data to be processed can be expected to be less than one hour.

In the figures above, the array deployment, the track and back azimuth determinations for Hurricane Igor (2010) are shown for detections north of the storm and south of the storm.

 

Treaty Compliance Verification

NCPA has been performing infrasound research in support of the monitoring regime of the Comprehensive Nuclear Test Ban Treaty under Contract W9113M-06-C-0029.  Significant achievements for this effort include developing and licensing a next generation, low-cost infrasound sensor, developing of laboratory calibration facilities, development of a technique for in-situ calibration of infrasound array elements, conducting large-scale experiments for infrasound propagation studies in the Middle East in 2009 and 2011 and at the Utah Test and Training Range in 2009 and 2010, conducting fundamental wind noise studies leading to the development of new physical and signal processing wind noise reduction methods, and developing and improving infrasound propagation models at atmospheric specifications.

Newly funded awards (PI and Co-PI names, funding agency, award title, date awarded) (Note:  These date back to 2010)

  • Daniel E. Kleinert, Jr., Weston Geophysical Corporation (Air Force Research Laboratory), Humming Skunk Installations, Validation and Preliminary Data Analysis, February 2013.
  • Richard Raspet, Army Research Laboratory, Cooperative work on infrasonic wind noise and infrasound applications – University of Mississippi and Army Research Laboratory, May 2013.
  • Richard Raspet, Army Research Office, Measurement and prediction of infrasonic wind noise in forests, September 2012.
  • Roger Waxler, Quanterra, Inc. (Incorporated Research Institutions for Seismology (IRIS)), Infrasound Sensors for the USArray, July 2010.

 

solarpanelInfrasound sensor deployment in Francis Marion National Forest, SC for research in monitoring of hurricanes.

 

solarpanel2Infrasound sensor deployment in Idaho for infrasound propagation studies.

 

sensorInfrasound sensor calibration facility.

 

Events & workshops

  • Infrasound Calibration Working Group.  The University of Mississippi sponsored a meeting of the Infrasound Calibration Working Group at the National Center for Physical Acoustics on 15-16 January 2013.  The purpose of the group is to provide an unbiased forum for all interested parties (excluding vendors) to develop, approve, and recommend procedures and processes for the characterization and calibration of infrasound sensing systems.  The group will also evaluate sensor/digitizer calibration facilities.  The next meeting is scheduled to occur at Sandia National Laboratory in Summer 2013.

Former Graduate Students (MA/MS & PhD)

Student’s name:  Jelle D. Assink

Advisors:  Roger Waxler and Adnan Aydin

Degree: Doctor of Philosophy, Geology & Geological Engineering

Year degree completed: 2012

Title of dissertation:  Infrasound as upper atmospheric monitor

 

Student’s name:  Phillip S. Blom

Advisor:  Roger Waxler

Degree:  Doctor of Philosophy, Physics

Year degree completed:  2013

Title of dissertation:  Interaction of the Cyclonic Winds with the Infrasonic Signal Generated by a Large Maritime Storm

 

Student’s name:  Jericho E. Cain

Advisor:  Richard Raspet

Degree:  Doctor of Philosophy, Physics

Year degree completed:  2013

Title of dissertation:  Large Eddy Simulation of Surface Pressure Fluctuations Generated by Elevated Gusts

 

Student’s name:  JohnPaul Abbott

Advisor:  Richard Raspet

Degree:  Doctor of Philosophy, Physics

Year degree completed:  2013

Title of dissertation:  Optimization of Wind Fences for Infrasonic Wind Noise Reduction

 

Student’s name: Vijay Emani

Advisor:  Carrick L. Talmadge

Degree:  Master of Science

Year degree completed:  2004

Title of dissertation:  Highway Noise Prediction Model and Validation

 

Student’s name: Shantharam V. Dravida

Advisor:  Carrick L. Talmadge

Degree:  Doctor of Philosophy, Engineering

Year degree completed:  2007

Title of dissertation:  Development of a Self- Calibrating Infrasound Microphone and its Adaptability to Lower Audible Frequencies

 

Student’s name: Shantharam V. Dravida

Advisor:  Carrick L. Talmadge

Degree:  Master of Science, Mechanical Engineering

Year degree completed:  2003

Title of dissertation:  Experimental characterization of modified and thin film piezoceramic sensors

 

Student’s name: Venugopal R. Male

Advisor:  Carrick L. Talmadge

Degree:  Master of Science

Year degree completed:  2007

Title of dissertation:  Modeling of acoustic and E&M Wave Propagation for Remote Sensing Applications in Atmospheric Boundary Layer

 

Student’s name: Amy Chrestman

Advisor:  Richard Raspet

Degree:  Master of Science, Physics

Year degree completed:  1989

Title of dissertation:  Validity of the ray approximation applied to sound propagation in the atmosphere

 

Student’s name: Mark W. Sprague

Advisor:  Richard Raspet

Degree:  Master of Science, Physics

Year degree completed:  1991

Title of dissertation:  A comparison of techniques for the measurement of acoustic ground impedance at low frequency

 

Student’s name: Mark W. Sprague

Advisor:  Richard Raspet

Degree:  Doctor of Philosophy, Physics

Year degree completed:  1994

Title of dissertation:  The prediction of sound levels in the atmosphere using a two dimensional fast field program

 

Student’s name: Michael Scott Morgan

Advisor:  Richard Raspet

Degree:  Doctor of Philosophy, Physics

Year degree completed:  1993

Title of dissertation:  An investigation of the sources and attenuation of wind noise in measurement microphones

 

Student’s name: Michael Scott Morgan

Advisor:  Richard Raspet

Degree:  Master of Science, Physics

Year degree completed:  1989

Title of dissertation:  Digital-to-analog conversion of acoustic signals

 

Student’s name: Wei Wei

Advisor:  Richard Raspet

Degree:  Doctor of Philosophy, Physics

Year degree completed:  1994

Title of dissertation:  Underwater measurement of the sound-intensity vector: its use in locating sound sources, and in measuring the sound power of stationary and moving sources

 

Student’s name: Patrice Marc Boulanger

Advisor:  Richard Raspet

Degree:  Master of Science, Physics

Year degree completed:  1992

Title of dissertation:  Sound propagation from the advanced turboprop aircraft in a turbulent atmosphere

 

Student’s name: Patrice Marc Boulanger

Advisor:  Richard Raspet

Degree:  Doctor of Philosophy, Physics

Year degree completed:  1994

Title of dissertation:  Sonic boom propagation through a realistic turbulent atmosphere

 

Student’s name: David W. Craig

Advisor:  Richard Raspet

Degree:  Doctor of Philosophy, Physics

Year degree completed:  1995

Title of dissertation:  Acoustic propagation in fractal porous media

 

Student’s name: James R. Belcher

Advisor:  Richard Raspet

Degree:  Doctor of Philosophy, Physics

Year degree completed:  1996

Title of dissertation:  A study of element interactions in thermoacoustic engines

 

Student’s name: Jay A. Lightfoot

Advisor:  Richard Raspet

Degree:  Doctor of Philosophy, Physics

Year degree completed:  1997

Title of dissertation:  Thermoacoustic engines in alternate geometry resonators

 

Student’s name: Mark C. Kelly

Advisor:  Richard Raspet

Degree:  Master of Science, Physics

Year degree completed:  1997

Title of dissertation:  Scattering of sonic booms by anisotropic turbulence in the atmosphere

 

Student’s name: Wayne Prather

Advisor:  Richard Raspet

Degree:  Doctor of Philosophy, Physics

Year degree completed:  1999

Title of dissertation:  Parametric excitation of a resonant acoustic mode

 

Student’s name: Gordon Smith

Advisor:  Richard Raspet

Degree:  Doctor of Philosophy, Physics

Year degree completed:  2000

Title of dissertation:  Examination of streaming regions within a heat-driven thermoacoustic refrigerator

 

Student’s name: Michael L. Oelze

Advisor:  Richard Raspet

Degree:  Doctor of Philosophy, Physics

Year degree completed:  2000

Title of dissertation:  Roughness characterization of porous soil using acoustic backscatter

 

Student’s name: William V. Slaton

Advisor:  Richard Raspet

Degree:  Doctor of Philosophy, Physics

Year degree completed:  2001

Title of dissertation:  Inert gas: vapor mixtures in thermoacoustics

 

Student’s name: Timothy G. Simmons

Advisor:  Richard Raspet

Degree:  Doctor of Philosophy, Physics

Year degree completed:  2003

Title of dissertation:  Experimental determination of thermoacoustic stack properties

 

Student’s name: Pasquale Montanaro

Advisor:  Richard Raspet

Degree:  Master of Science, Physics

Year degree completed:  2004

Title of dissertation:  The acoustics of fluid motion in porous media

 

Student’s name: Kevin Dillion

Advisor:  Richard Raspet

Degree:  Master of Science, Physics

Year degree completed:  2005

Title of dissertation:  An investigation of wind noise over a flat plate

 

Student’s name: Jiao Yu

Advisor:  Richard Raspet

Degree:  Doctor of Philosophy, Physics

Year degree completed:  2009

Title of dissertation:  Calculation of wind noise measured at the surface under turbulent wind fields

 

Student’s name: Jiao Yu

Advisor:  Richard Raspet

Degree:  Master of Science, Physics

Year degree completed:  2007

Title of dissertation:  Infrasound wind noise predictions

 

Student’s name: Carl Jensen

Advisor:  Richard Raspet

Degree:  Doctor of Philosophy, Physics

Year degree completed:

Title of dissertation:  Computational thermoacoustics in fibrous stacks