  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 time-distance helioseismology to
image flows in the solar interior. We downsample and synthesize 900 billion
wavefield observations to produce 3 billion cross-correlations, 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 spherical-harmonic degree $\ell$. Within the wavenumber band
$\ell<60$, Convective velocities are 20-100 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 $\ell<60$, with Rossby numbers
smaller than $\sim10^{-2}$ at $r/R_\odot=0.96$, suggesting that the Sun may be
a much faster rotator than previously thought, and that large-scale convection
may be quasi-geostrophic. The fact that iso-rotation contours in the Sun are
not co-aligned with the axis of rotation suggests the presence of a latitudinal
entropy gradient.
