Research and Forecast (WRF) Version 3 and tested with two planetary

boundary layer (PBL) schemes, the Bougeault-Lacarre (1989) and the

Mellor-Yamada -Janjic (MYJ) scheme. The multi-layer urban scheme

solves the energy balance for roofs, roads and buildings at several

vertical levels within the urban canopy and provides source terms for

the prognostic equations for T, q, u, v and turbulent kinetic energy

(TKE) that are solved in the respective PBL schemes. Varying vertical

building density is considered in the model and this UCm is coupled

to the Noah land surface model, which calculates surface fluxes from

natural surfaces in urban areas.

The Bougeault-Lacarrere(1989) scheme calculates the TKE

prognostically and uses length scales (estimated from the vertical

profile of potential temperature and TKE) to calculate the

dissipation and the turbulent coefficients. The MYJ scheme

calculates changes in TKE due to shear, buoyancy and dissipation and

subsequently diffuses TKE vertically.

Results of the simulated wind and temperature fields as well the

structure of the planetary boundary layer for an idealized 2-d case

will be presented for both PBL schemes as well as with alternative

urban land cover parameterizations (the urbanized Noah LSM, and a

single-layer UCM). Also will be discussed are preliminary results

from applying this WRF/UCM to a case study during the TexAQS-2000

field experiment over the Greater Houston region.