  The solar chromosphere contains thin, highly dynamic strands of plasma known
as spicules. Recently, it has been suggested that the smallest and fastest
(Type II) spicules are identical to intermittent jets observed by the Interface
Region Imaging Spectrograph. These jets appear to expand out along open
magnetic field lines rooted in unipolar network regions of coronal holes. In
this paper we revisit a thirty-year-old idea that spicules may be caused by
upward forces associated with Alfven waves. These forces involve the conversion
of transverse Alfven waves into compressive acoustic-like waves that steepen
into shocks. The repeated buffeting due to upward shock propagation causes
nonthermal expansion of the chromosphere and a transient levitation of the
transition region. Some older models of wave-driven spicules assumed sinusoidal
wave inputs, but the solar atmosphere is highly turbulent and stochastic. Thus,
we model this process using the output of a time-dependent simulation of
reduced magnetohydrodynamic turbulence. The resulting mode-converted
compressive waves are strongly variable in time, with a higher transition
region occurring when the amplitudes are large and a lower transition region
when the amplitudes are small. In this picture, the transition region bobs up
and down by several Mm on timescales less than a minute. These motions produce
narrow, intermittent extensions of the chromosphere that have similar
properties as the observed jets and Type II spicules.
