Turbulent Mechanisms for the Deep Convective Boundary Layer in the Taklimakan Desert

The deep convective boundary layer (CBL) in the Taklimakan Desert plays an
important role in the climate system in East Asia. Based on the
observation experiment and large-eddy simulation, turbulent mechanisms for
its formation were revealed in this study. This explained why the daily
maximum CBL depth was independent of surface heating. In the late-morning,
there was a weak temperature inversion and a near-neutral residual layer
(RL) above the CBL.   With the development of the CBL,
stronger convection could penetrate the RL and even overshoot the top of
the RL. The distinctive boundary-layer process entrained free-tropospheric
air to warm the RL and then promoted the entrainment of the warmed air in
the RL into the CBL. This extra energy supply effectively contributed to
the growth of the CBL. With further positive feedback between the CBL and
RL depths, a deeper CBL would form in consecutive fair-weather conditions.