The existing atmospheric PBL parameterization schemes used in global or regional forecast models can be grouped into five generic types: the Richardson-number-dependent K model, the K-profile model, single-point second-order closure approaches, mixed-layer models, and multi-stream exchange models.  In this workshop, I will

1) describe these five types of PBL schemes,
2) point out their pros and cons in representing the PBL turbulence,
3) discuss methods for improving these schemes,
4) address difficulties and problems in the development of PBL parameterizations, and
5) the effects of boundary-layer physics on chemical reactivity.