Sound wave travel times in plage areas: The effect of abnormal granulation

K. Petrovay, R. Erdélyi, M. J. Thompson

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

We consider the effect that abnormal granulation observed in active regions should have on the propagation of acoustic waves. Any such effect is found to be limited to a shallow surface layer where sound waves propagate nearly vertically. The magnetically suppressed turbulence implies higher sound speeds, leading to shorter travel times. This time shift is independent of the travel distance, while it shows a characteristic dependence on the assumed plage field strength, plotted in Figure 2. As a consequence of the variation of the acoustic cutoff with height, the time shift is expected to be significantly higher for higher frequency waves within the observed regime of 3-5 mHz. The lower group velocity near the upper reflection point further leads to an increased envelope time shift, as compared to the phase shift. These characteristics of the time shifts are in accordance with observations. The calculated overall amplitude of the time shift is about ten seconds, comparable to, but still significantly less than suggested by measurements.

Original languageEnglish
Title of host publicationEuropean Space Agency, (Special Publication) ESA SP
Edition617
Publication statusPublished - Jul 2006
EventSOHO-17: 10 Years of SOHO and Beyond - Sicily, Italy
Duration: May 7 2006May 12 2006

Other

OtherSOHO-17: 10 Years of SOHO and Beyond
CountryItaly
CitySicily
Period5/7/065/12/06

Fingerprint

Granulation
Travel time
Acoustic waves
Phase shift
Turbulence
Acoustics

Keywords

  • Magnetohydrodynamics
  • MHD
  • Sun

ASJC Scopus subject areas

  • Aerospace Engineering

Cite this

Petrovay, K., Erdélyi, R., & Thompson, M. J. (2006). Sound wave travel times in plage areas: The effect of abnormal granulation. In European Space Agency, (Special Publication) ESA SP (617 ed.)

Sound wave travel times in plage areas : The effect of abnormal granulation. / Petrovay, K.; Erdélyi, R.; Thompson, M. J.

European Space Agency, (Special Publication) ESA SP. 617. ed. 2006.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Petrovay, K, Erdélyi, R & Thompson, MJ 2006, Sound wave travel times in plage areas: The effect of abnormal granulation. in European Space Agency, (Special Publication) ESA SP. 617 edn, SOHO-17: 10 Years of SOHO and Beyond, Sicily, Italy, 5/7/06.
Petrovay K, Erdélyi R, Thompson MJ. Sound wave travel times in plage areas: The effect of abnormal granulation. In European Space Agency, (Special Publication) ESA SP. 617 ed. 2006
Petrovay, K. ; Erdélyi, R. ; Thompson, M. J. / Sound wave travel times in plage areas : The effect of abnormal granulation. European Space Agency, (Special Publication) ESA SP. 617. ed. 2006.
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