Detection of zonal shear flows beneath the Sun's surface from f-mode frequency splitting

Research output: Contribution to journalArticle

72 Citations (Scopus)

Abstract

We report on the first successful measure of the zonal variations of the Sun's differential rotation (so-called torsional oscillations) by helioseismology. Using new helioseismic data from the Michelson Doppler Imager on board SOHO, we have detected zonal flow bands with velocity variation of 5 m s-1 at a depth of 2-9 Mm beneath the surface. The subsurface flow is inferred from rotational splitting of frequencies of the fundamental mode of solar oscillations in the range of angular degree l from 120 to 250, using a 144 day uninterrupted time series of the Sun's Doppler velocities. The structure of the subsurface shear flow resembles the pattern of the torsional oscillations observed on the surface. Comparing with previous surface measurements, we found evidence for migration of the flow bands towards the equator.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume482
Issue number2 PART II
StatePublished - Jan 1 1997

Fingerprint

zonal flow
shear flow
sun
oscillation
subsurface flow
solar oscillations
helioseismology
oscillations
daytime
equators
time series
detection

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Convection
  • Methods: data analysis
  • Sun: activity
  • Sun: interior
  • Sun: oscillations
  • Sun: rotation

Cite this

@article{b6205c2d33d34de48e3630300416e2ce,
title = "Detection of zonal shear flows beneath the Sun's surface from f-mode frequency splitting",
abstract = "We report on the first successful measure of the zonal variations of the Sun's differential rotation (so-called torsional oscillations) by helioseismology. Using new helioseismic data from the Michelson Doppler Imager on board SOHO, we have detected zonal flow bands with velocity variation of 5 m s-1 at a depth of 2-9 Mm beneath the surface. The subsurface flow is inferred from rotational splitting of frequencies of the fundamental mode of solar oscillations in the range of angular degree l from 120 to 250, using a 144 day uninterrupted time series of the Sun's Doppler velocities. The structure of the subsurface shear flow resembles the pattern of the torsional oscillations observed on the surface. Comparing with previous surface measurements, we found evidence for migration of the flow bands towards the equator.",
keywords = "Convection, Methods: data analysis, Sun: activity, Sun: interior, Sun: oscillations, Sun: rotation",
author = "Alexander Kosovichev and J. Schou",
year = "1997",
month = "1",
day = "1",
language = "English (US)",
volume = "482",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2 PART II",

}

Detection of zonal shear flows beneath the Sun's surface from f-mode frequency splitting. / Kosovichev, Alexander; Schou, J.

In: Astrophysical Journal, Vol. 482, No. 2 PART II, 01.01.1997.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Detection of zonal shear flows beneath the Sun's surface from f-mode frequency splitting

AU - Kosovichev, Alexander

AU - Schou, J.

PY - 1997/1/1

Y1 - 1997/1/1

N2 - We report on the first successful measure of the zonal variations of the Sun's differential rotation (so-called torsional oscillations) by helioseismology. Using new helioseismic data from the Michelson Doppler Imager on board SOHO, we have detected zonal flow bands with velocity variation of 5 m s-1 at a depth of 2-9 Mm beneath the surface. The subsurface flow is inferred from rotational splitting of frequencies of the fundamental mode of solar oscillations in the range of angular degree l from 120 to 250, using a 144 day uninterrupted time series of the Sun's Doppler velocities. The structure of the subsurface shear flow resembles the pattern of the torsional oscillations observed on the surface. Comparing with previous surface measurements, we found evidence for migration of the flow bands towards the equator.

AB - We report on the first successful measure of the zonal variations of the Sun's differential rotation (so-called torsional oscillations) by helioseismology. Using new helioseismic data from the Michelson Doppler Imager on board SOHO, we have detected zonal flow bands with velocity variation of 5 m s-1 at a depth of 2-9 Mm beneath the surface. The subsurface flow is inferred from rotational splitting of frequencies of the fundamental mode of solar oscillations in the range of angular degree l from 120 to 250, using a 144 day uninterrupted time series of the Sun's Doppler velocities. The structure of the subsurface shear flow resembles the pattern of the torsional oscillations observed on the surface. Comparing with previous surface measurements, we found evidence for migration of the flow bands towards the equator.

KW - Convection

KW - Methods: data analysis

KW - Sun: activity

KW - Sun: interior

KW - Sun: oscillations

KW - Sun: rotation

UR - http://www.scopus.com/inward/record.url?scp=0001121819&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0001121819&partnerID=8YFLogxK

M3 - Article

VL - 482

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2 PART II

ER -