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Title: Magnetically Modulated Heat Transport in a Global Simulation of Solar Magneto-convection

Abstract

We present results from a global MHD simulation of solar convection in which the heat transported by convective flows varies in-phase with the total magnetic energy. The purely random initial magnetic field specified in this experiment develops into a well-organized large-scale antisymmetric component undergoing hemispherically synchronized polarity reversals on a 40 year period. A key feature of the simulation is the use of a Newtonian cooling term in the entropy equation to maintain a convectively unstable stratification and drive convection, as opposed to the specification of heating and cooling terms at the bottom and top boundaries. When taken together, the solar-like magnetic cycle and the convective heat flux signature suggest that a cyclic modulation of the large-scale heat-carrying convective flows could be operating inside the real Sun. We carry out an analysis of the entropy and momentum equations to uncover the physical mechanism responsible for the enhanced heat transport. The analysis suggests that the modulation is caused by a magnetic tension imbalance inside upflows and downflows, which perturbs their respective contributions to heat transport in such a way as to enhance the total convective heat flux at cycle maximum. Potential consequences of the heat transport modulation for solar irradiance variabilitymore » are briefly discussed.« less

Authors:
 [1];  [2];  [3];  [4]
  1. Laboratory for Atmospheric and Space Physics, Campus Box 600, University of Colorado, Boulder, CO 80303 (United States)
  2. Département de Physique, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, QC H3C 3J7 (Canada)
  3. European Centre for Medium-Range Weather Forecasts, Reading, RG2 9AX (United Kingdom)
  4. Department of Astrophysical and Planetary Sciences, Laboratory for Atmospheric and Space Physics, Campus Box 391, University of Colorado, Boulder, CO 80303 (United States)
Publication Date:
OSTI Identifier:
22663572
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 841; 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; CONVECTION; ENTROPY; EQUATIONS; HEAT FLUX; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; MODULATION; RADIANT FLUX DENSITY; RANDOMNESS; SIMULATION; SPECIFICATIONS; STRATIFICATION; SUN; TURBULENCE

Citation Formats

Cossette, Jean-Francois, Charbonneau, Paul, Smolarkiewicz, Piotr K., and Rast, Mark P., E-mail: Jean-Francois.Cossette@lasp.colorado.edu, E-mail: paulchar@astro.umontreal.ca, E-mail: smolar@ecmwf.int, E-mail: Mark.Rast@lasp.colorado.edu. Magnetically Modulated Heat Transport in a Global Simulation of Solar Magneto-convection. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA6D60.
Cossette, Jean-Francois, Charbonneau, Paul, Smolarkiewicz, Piotr K., & Rast, Mark P., E-mail: Jean-Francois.Cossette@lasp.colorado.edu, E-mail: paulchar@astro.umontreal.ca, E-mail: smolar@ecmwf.int, E-mail: Mark.Rast@lasp.colorado.edu. Magnetically Modulated Heat Transport in a Global Simulation of Solar Magneto-convection. United States. doi:10.3847/1538-4357/AA6D60.
Cossette, Jean-Francois, Charbonneau, Paul, Smolarkiewicz, Piotr K., and Rast, Mark P., E-mail: Jean-Francois.Cossette@lasp.colorado.edu, E-mail: paulchar@astro.umontreal.ca, E-mail: smolar@ecmwf.int, E-mail: Mark.Rast@lasp.colorado.edu. Sat . "Magnetically Modulated Heat Transport in a Global Simulation of Solar Magneto-convection". United States. doi:10.3847/1538-4357/AA6D60.
@article{osti_22663572,
title = {Magnetically Modulated Heat Transport in a Global Simulation of Solar Magneto-convection},
author = {Cossette, Jean-Francois and Charbonneau, Paul and Smolarkiewicz, Piotr K. and Rast, Mark P., E-mail: Jean-Francois.Cossette@lasp.colorado.edu, E-mail: paulchar@astro.umontreal.ca, E-mail: smolar@ecmwf.int, E-mail: Mark.Rast@lasp.colorado.edu},
abstractNote = {We present results from a global MHD simulation of solar convection in which the heat transported by convective flows varies in-phase with the total magnetic energy. The purely random initial magnetic field specified in this experiment develops into a well-organized large-scale antisymmetric component undergoing hemispherically synchronized polarity reversals on a 40 year period. A key feature of the simulation is the use of a Newtonian cooling term in the entropy equation to maintain a convectively unstable stratification and drive convection, as opposed to the specification of heating and cooling terms at the bottom and top boundaries. When taken together, the solar-like magnetic cycle and the convective heat flux signature suggest that a cyclic modulation of the large-scale heat-carrying convective flows could be operating inside the real Sun. We carry out an analysis of the entropy and momentum equations to uncover the physical mechanism responsible for the enhanced heat transport. The analysis suggests that the modulation is caused by a magnetic tension imbalance inside upflows and downflows, which perturbs their respective contributions to heat transport in such a way as to enhance the total convective heat flux at cycle maximum. Potential consequences of the heat transport modulation for solar irradiance variability are briefly discussed.},
doi = {10.3847/1538-4357/AA6D60},
journal = {Astrophysical Journal},
number = 1,
volume = 841,
place = {United States},
year = {Sat May 20 00:00:00 EDT 2017},
month = {Sat May 20 00:00:00 EDT 2017}
}