skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: UNDERSTANDING SOLAR TORSIONAL OSCILLATIONS FROM GLOBAL DYNAMO MODELS

Abstract

The phenomenon of solar “torsional oscillations” (TO) represents migratory zonal flows associated with the solar cycle. These flows are observed on the solar surface and, according to helioseismology, extend through the convection zone. We study the origin of the TO using results from a global MHD simulation of the solar interior that reproduces several of the observed characteristics of the mean-flows and magnetic fields. Our results indicate that the magnetic tension (MT) in the tachocline region is a key factor for the periodic changes in the angular momentum transport that causes the TO. The torque induced by the MT at the base of the convection zone is positive at the poles and negative at the equator. A rising MT torque at higher latitudes causes the poles to speed up, whereas a declining negative MT torque at the lower latitudes causes the equator to slow-down. These changes in the zonal flows propagate through the convection zone up to the surface. Additionally, our results suggest that it is the magnetic field at the tachocline that modulates the amplitude of the surface meridional flow rather than the opposite as assumed by flux-transport dynamo models of the solar cycle.

Authors:
 [1];  [2];  [3];  [4];  [5]
  1. Physics Department, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, Belo Horizonte, MG, 31270-901 (Brazil)
  2. European Centre for Medium-Range Weather Forecasts, Reading RG2 9AX (United Kingdom)
  3. Astronomy Department, Universidade de São Paulo, IAG-USP, Rua do Matão, 1226, São Paulo, SP, 05508-090 (Brazil)
  4. New Jersey Institute of Technology, Newark, NJ 07103 (United States)
  5. NASA, Ames Research Center, Moffett Field, Mountain View, CA 94040 (United States)
Publication Date:
OSTI Identifier:
22654234
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 828; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMPLITUDES; ANGULAR MOMENTUM; CONVECTION; EQUATOR; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; OSCILLATIONS; PERIODICITY; ROTATION; SIMULATION; SOLAR CYCLE; SUN; SURFACES; TORQUE; VELOCITY

Citation Formats

Guerrero, G., Smolarkiewicz, P. K., Pino, E. M. de Gouveia Dal, Kosovichev, A. G., and Mansour, N. N., E-mail: guerrero@fisica.ufmg.br, E-mail: smolar@ecmwf.int, E-mail: dalpino@astro.iag.usp.br, E-mail: alexander.g.kosovichev@njit.edu, E-mail: Nagi.N.Mansour@nasa.gov. UNDERSTANDING SOLAR TORSIONAL OSCILLATIONS FROM GLOBAL DYNAMO MODELS. United States: N. p., 2016. Web. doi:10.3847/2041-8205/828/1/L3.
Guerrero, G., Smolarkiewicz, P. K., Pino, E. M. de Gouveia Dal, Kosovichev, A. G., & Mansour, N. N., E-mail: guerrero@fisica.ufmg.br, E-mail: smolar@ecmwf.int, E-mail: dalpino@astro.iag.usp.br, E-mail: alexander.g.kosovichev@njit.edu, E-mail: Nagi.N.Mansour@nasa.gov. UNDERSTANDING SOLAR TORSIONAL OSCILLATIONS FROM GLOBAL DYNAMO MODELS. United States. doi:10.3847/2041-8205/828/1/L3.
Guerrero, G., Smolarkiewicz, P. K., Pino, E. M. de Gouveia Dal, Kosovichev, A. G., and Mansour, N. N., E-mail: guerrero@fisica.ufmg.br, E-mail: smolar@ecmwf.int, E-mail: dalpino@astro.iag.usp.br, E-mail: alexander.g.kosovichev@njit.edu, E-mail: Nagi.N.Mansour@nasa.gov. Thu . "UNDERSTANDING SOLAR TORSIONAL OSCILLATIONS FROM GLOBAL DYNAMO MODELS". United States. doi:10.3847/2041-8205/828/1/L3.
@article{osti_22654234,
title = {UNDERSTANDING SOLAR TORSIONAL OSCILLATIONS FROM GLOBAL DYNAMO MODELS},
author = {Guerrero, G. and Smolarkiewicz, P. K. and Pino, E. M. de Gouveia Dal and Kosovichev, A. G. and Mansour, N. N., E-mail: guerrero@fisica.ufmg.br, E-mail: smolar@ecmwf.int, E-mail: dalpino@astro.iag.usp.br, E-mail: alexander.g.kosovichev@njit.edu, E-mail: Nagi.N.Mansour@nasa.gov},
abstractNote = {The phenomenon of solar “torsional oscillations” (TO) represents migratory zonal flows associated with the solar cycle. These flows are observed on the solar surface and, according to helioseismology, extend through the convection zone. We study the origin of the TO using results from a global MHD simulation of the solar interior that reproduces several of the observed characteristics of the mean-flows and magnetic fields. Our results indicate that the magnetic tension (MT) in the tachocline region is a key factor for the periodic changes in the angular momentum transport that causes the TO. The torque induced by the MT at the base of the convection zone is positive at the poles and negative at the equator. A rising MT torque at higher latitudes causes the poles to speed up, whereas a declining negative MT torque at the lower latitudes causes the equator to slow-down. These changes in the zonal flows propagate through the convection zone up to the surface. Additionally, our results suggest that it is the magnetic field at the tachocline that modulates the amplitude of the surface meridional flow rather than the opposite as assumed by flux-transport dynamo models of the solar cycle.},
doi = {10.3847/2041-8205/828/1/L3},
journal = {Astrophysical Journal Letters},
number = 1,
volume = 828,
place = {United States},
year = {Thu Sep 01 00:00:00 EDT 2016},
month = {Thu Sep 01 00:00:00 EDT 2016}
}