We also assessed the relative contributions of surface-layer schemes to the typical features
of each PBL parametrization, noting that the surface-layer formulations differ according to
PBL schemes used. It was found that thermodynamic surface variables are more strongly
influenced by the surface-layer schemes than by the vertical mixing algorithms of PBL parametrizations,
in both convective and stable regimes. However, the near-surface momentum
depends on the vertical diffusion schemes in the unstable regime. Compared to the surface
variables, vertical profiles are less dependent on the surface-layer schemes. The surfacelayer
parametrizations only contribute to near-surface variability in both unstable and stable
regimes, whereas the shapes of the profiles are determined by the PBL mixing algorithms.
In the recent study of Nolan et al. (2009), it was shown that a modification in surface-layer
formulations that considers a more recently formulated ocean roughness length improves
their hurricane simulations with both the YSU and MYJ schemes. This implies that there
are possibly many error sources in the surface-layer schemes, and these errors can affect the
performance of PBL parametrizations.