About Me

Aspiring geophysicist and scientific computer. Runner. Coffee drinker.
Carolina alum. and March Madness fan.


Website build in progress.

Research

My primary research interests are:

  1. Numerical Wave Propagation
  2. Theoretical Acoustics and Seismology
  3. Applied Statistics, Array Processing, and Inverse Theory

I am also interested in open source software projects, and I am a co-developer/maintainer of the following packages on Github.

  1. lts_array : Least trimmed squres infrasound array processing.
  2. array_processing : General infrasound array processing tools.

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Peer-Reviewed Publications

  1. J.W. Bishop, D. Fee , R. Modrak, C. Tape, and K. Kim. (2022). Spectral element modeling of acoustic to seismic coupling over topography. Journal of Geophysical Research: Solid Earth, e2021JB023142. 127, https://doi.org/10.1029/2021JB023142.
  2. J.W. Bishop, D. Fee , C.A.L. Szuberla. Improved infrasound array processing with robust estimators , Geophysical Journal International, Volume 221, Issue 3, June 2020, Pages 2058–2074, https://doi.org/10.1093/gji/ggaa110
  3. J.W. Bishop, J.M. Lees, C.B. Biryol, T.D. Mikesell, L. Franco, 2018. Examining the interior of Llaima Volcano with receiver functions, JVGR, 352, 1-9 https://doi.org/10.1016/j.jvolgeores.2017.11.022

Selected Talks and Conference Presentations

  1. Bishop, J.W., Blom, P.S., Fee, D. (2021), Modeling Infrasound Propagation with Realistic Terrain and Atmospheres Using a Three-Dimensional Finite-Difference Time-Domain Method, American Geophysical Union Fall Meeting.
  2. Fee, D., Waxler, R., Matoza, R.M. and Bishop, J.W. (2020), Results and Recommendations of the Infrasound Propagation Working Group, American Geophysical Union Fall Meeting.
  3. Invited Talk Improved Infrasound Array Processing with Robust Estimators (2019) 177th Meeting of the Acoustical Society of America

      Full List Here

Research Projects

A short summary of my PhD projects.

Improved infrasound array processing with robust estimators

Here we introduce robust regression techniques into the infrasound array processing literature by comparing the performance of various algorithms on actual and synthetically flawed array data. Our results show that robust estimators provide more accurate plane wave parameter estimates than conventional least-squares processing when there are problems with the data, and perform similarly when no issues exist. In addition to improved estimates, evaluation of least trimmed squares weights identified data quality issues in both the synthetic and active array data examples.

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Spectral Element Modeling of Acoustic to Seismic Coupling Over Topography

Acoustic waves in the atmosphere are commonly recorded on seismometers as they couple into the ground. These signals, here called ground coupled airwaves, are not commonly considered in numerical modeling of infrasound propagation, which often assumes a rigid unmeshed boundary. Starting from an analytically-tractable spherical wave model, we analyze how the coupling of an acoustic wave into a planar elastic halfspace changes over a wide range of scenarios. We use energy admittance to quantify acoustic to seismic coupling over both a planar elastic halfspace and meshed topography. Our spectral element and analytic calculations have different maxima as a function of incidence angle, with very high admittance values for near-vertical incidence (maximum ≈78%). Energy admittance calculations at shallow incidence angles are much smaller (less than 1%). In simulations over the complex topography of Sakurajima Volcano, we attribute the variable spatial pattern of energy admittance to changes in earth parameters between each model. The observed pressure difference over the simulated 15 km region appears to be < 2% . While this value is relatively small, the cumulative addition over 100s of km and multiple acoustic bounce points may be significant. Acoustic to seismic coupling along the propagation path may bias long distance yield estimates, particularly when infrasound propagates over regions with steep topography or particularly slow seismic velocities, such as alluvial planes.

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