Driving Solar Giant Cells through the Self-Organization of Near-Surface Plumes

Abstract

Global 3D simulations of solar giant-cell convection have provided significant insight into the processes which yield the Sun's observed differential rotation and cyclic dynamo action. However, as we move to higher resolution simulations a variety of codes have encountered what has been termed the convection conundrum. As these simulations increase in resolution and hence the level of turbulence achieved, they tend to produce weak or even anti-solar differential rotation patterns associated with a weak rotational influence (high Rossby number) due to large convective velocities. One potential culprit for this convection conundrum is the upper boundary condition applied in most simulations which is generally impenetrable. Here we present an alternative stochastic plume boundary condition which imposes small-scale convective plumes designed to mimic near-surface convective downflows, thus allowing convection to carry the majority of the outward solar energy flux up to and through our simulated upper boundary. The use of a plume boundary condition leads to significant changes in the convective driving realized in the simulated domain and thus to the convective energy transport, the dominant scale of the convective enthalpy flux, and the relative strength of the strongest downflows, the downflow network, and the convective upflows. These changes are present even far from the upper boundary layer. Additionally, we demonstrate that in spite of significant changes, giant cell morphology in the convective patterns is still achieved with self-organization of the imposed boundary plumes into downflow lanes, cellular patterns, and even rotationally-aligned banana cells in equatorial regions. This plume boundary presents an alternative pathway for 3D global convection simulations where driving is non-local and may provide a new approach towards addressing the convection conundrum.

arXiv commentAccepted for publication in ApJ; 21 pages w/ 14 figures

References in corpus (49)

• Large scale dynamics in turbulent Rayleigh-Benard convection
• Global-Scale Turbulent Convection and Magnetic Dynamo Action in the Solar Envelope
• Radiative MHD simulation of sunspot structure
• Solar Interior Rotation and its Variation
• Simulation of the Formation of a Solar Active Region
• Turbulent Convection Under the Influence of Rotation: Sustaining a Strong Differential Rotation
• Persistent Magnetic Wreaths in a Rapidly Rotating Sun
• Solar differential rotation and meridional flow: The role of a subadiabatic tachocline for the Taylor-Proudman balance
• Structure and Evolution of Giant Cells in Global Models of Solar Convection
• Dynamo Action in the Solar Convection Zone and Tachocline: Pumping and Organization of Toroidal Fields
• From solar-like to anti-solar differential rotation in cool stars
• Anomalously Weak Solar Convection
• Magnetic Wreaths and Cycles in Convective Dynamos
• Meridional Circulation in Solar and Stellar Convection Zones
• A simulation of convective dynamo in the solar convective envelope: maintenance of the solar-like differential rotation and emerging flux
• The Sun's Supergranulation
• Giant Convection Cells Found on the Sun
• Dipolar versus multipolar dynamos: the influence of the background density stratification
• Seismic Sounding of Convection in the Sun
• Magnetically controlled stellar differential rotation near the transition from solar to anti-solar profiles
• High-resolution calculation of the solar global convection with the reduced speed of sound technique: II. Near surface shear layer with the rotation
• Gyroscopic Pumping in the Solar Near-Surface Shear Layer
• The Mass Mixing Length in Convective Stellar Envelopes
• The Spectral Amplitude of Stellar Convection and its Scaling in the High-Rayleigh-Number Regime
• Helioseismic Imaging of Fast Convective Flows Throughout the Near-Surface Shear Layer
• The Emergence of Solar Supergranulation as a Natural Consequence of Rotationally-Constrained Interior Convection
• High-resolution calculations of the solar global convection with the reduced speed of sound technique: I. The structure of the convection and the magnetic field without the rotation
• Supergranules as Probes of the Sun's Meridional Circulation
• Stellar mixing length theory with entropy rain
• Extended subadiabatic layer in simulations of overshooting convection
• On the Amplitude of Convective Velocities in the Deep Solar Interior
• Magnetic cycles in a dynamo simulation of fully convective M-star Proxima Centauri
• The Role of Subsurface Flows in Solar Surface Convection: Modeling the Spectrum of Supergranular and Larger Scale Flows
• Velocity Amplitudes in Global Convection Simulations: The Role of the Prandtl Number and Near-Surface Driving
• The Sun's Photospheric Convection Spectrum
• Solar overshoot region and small-scale dynamo with realistic energy flux
• Influence of a coronal envelope as a free boundary to global convective dynamo simulations
• Supergranulation as the largest buoyantly driven convective scale of the Sun
• Seismic Constraints on Interior Solar Convection
• Supergranulation and multiscale flows in the solar photosphere: Global observations vs. a theory of anisotropic turbulent convection
• Dynamo action and magnetic buoyancy in convection simulations with vertical shear
• Identifying Potential Markers of the Sun's Giant Convective Scale
• Differential Rotation in Magnetized and Non-magnetized Stars
• Convective velocity suppression via the enhancement of subadiabatic layer: Role of the effective Prandtl number
• Meridional circulation dynamics from 3D MHD global simulations of solar convection
• Weakly non-Boussinesq convection in a gaseous spherical shell
• Modeling the Near-Surface Shear Layer: Diffusion Schemes Studied With CSS
• Generating buoyant magnetic flux ropes in solar-like convective dynamos
• Differential Rotation in Solar Convective Dynamo Simulations

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• Overshooting in simulations of compressible convection
• Hydrodynamic Properties of the Sun's Giant Cellular Flows
• The Role of Downflows in Establishing Solar Near-Surface Shear
• Effects of a subadiabatic layer on convection and dynamos in spherical wedge simulations
• Sensitivity to luminosity, centrifugal force, and boundary conditions in spherical shell convection
• Theory of solar oscillations in the inertial frequency range: Amplitudes of equatorial modes from a nonlinear rotating convection simulation
• Revisiting the Sun's Strong Differential Rotation along Radial Lines
• Prandtl number dependence of compressible convection: Flow statistics and convective energy transport
• Photospheric downflows observed with SDO/HMI, HINODE, and an MHD simulation
• Three-dimensional non-kinematic simulation of post-emergence evolution of bipolar magnetic regions and Babcock-Leighton dynamo of the Sun
• Overstable Convective Modes in a Polytropic Stellar Atmosphere
• Simulations of entropy rain-driven convection
• Link between trees of fragmenting granules and deep downflows in MHD simulation
• Comparison of time-distance inversion methods applied to SDO/HMI Dopplergrams
• Simulating the outer layers of rapidly rotating stars
• Radial Trapping of Thermal Rossby Waves within the Convection Zones of Low-Mass Stars
• Granulation and Convectional Driving on Stellar Surfaces