Over arid regions in north-west China, the atmospheric boundary layer can be
extremely high during daytime in late spring and summer. For instance, the depth of the
observed convective boundary layer can exceed 3,000m or even be up to 4,000m at some
stations. In order to characterize the atmospheric boundary-layer (ABL) conditions and to
understand themechanisms that produce such an extreme boundary-layer height, an advanced
research version of the community weather research and forecasting numerical model (WRF)
is employed to simulate observed extreme boundary-layer heights in May 2000. The ability
of theWRF model in simulating the atmospheric boundary layer over arid areas is evaluated.
Several key parameters that contribute to the extremely deep boundary layer are identified
through sensitivity experiments, and it is found that theWRF model is able to capture characteristics
of the observed deep atmospheric boundary layer. Results demonstrate the influence
of soil moisture and surface albedo on the simulation of the extremely deep boundary layer.
In addition, the choice of land-surface model and forecast lead times also plays a role in the
accurate numerical simulation of the ABL height.