

Anomalously Weak Solar Convection
Type:


Journal, Article

Title:


Anomalously Weak Solar Convection

Author(s):


Hanasoge, S.; Duvall Jr, T. L.; Sreenivasan, K. R.

Date:


2012/06/14

Abstract:


Convection in the solar interior is thought to comprise structures on a spectrum of scales. This conclusion emerges from phenomenological studies and numerical simulations, though neither covers the proper range of dynamical parameters of solar convection. Here, we analyze observations of the wavefield in the solar photosphere using techniques of timedistance helioseismology to image flows in the solar interior. We downsample and synthesize 900 billion wavefield observations to produce 3 billion crosscorrelations, which we average and fit, measuring 5 million wave travel times. Using these travel times, we deduce the underlying flow systems and study their statistics to bound convective velocity magnitudes in the solar interior, as a function of depth and sphericalharmonic degree ℓ. Within the wavenumber band ℓ < 60, Convective velocities are 20100 times weaker than current theoretical estimates. This suggests the prevalence of a different paradigm of turbulence from that predicted by existing models, prompting the question: what mechanism transports the heat flux of a solar luminosity outwards? Advection is dominated by Coriolis forces for wavenumbers ℓ < 60 , with Rossby numbers smaller than ~ 10^{2} at r/R⊙ = .96, suggesting that the Sun may be a much faster rotator than previously thought, and that largescale convection may be quasigeostrophic. The fact that isorotation contours in the Sun are not coaligned with the axis of rotation suggests the presence of a latitudinal entropy gradient.

Journal (full):


arxiv.org

Start Page:


1206.3173

Link:


http://arxiv.org/abs/1206.3173

Link (PDF):


http://arxiv.org/pdf/1206.3173

