Testing of Urban Canopy Wind Profile Parameterization for Atmospheric Emergency Response Modeling System

Simulation and forecasting of wind fields in the urban canopy layer (UCL) is important for developing and implementing measures for atmospheric emergency response. To reflect the impact of the UCL on wind fields and to fulfill rapid emergency response requirements, an urban canopy wind profile parameterization method (UCPM) proposed by MacDonald (2000) is coupled with the mesoscale model MM5. The performance of the UCPM is tested with observations from a 325-m meteorological tower in Beijing from 18 Jul to 6 Aug 2010. The results demonstrate that the UCPM accurately reproduces wind profiles in the UCL under neutral, stable, and unstable conditions with normalized mean bias of 78%, 12%, and 4%, respectively, and normalized mean error of 78%, 52%, and 21%, respectively. The UCPM shows excellent performances at heights of 8, 15, 32, and 47 m within the UCL with normalized mean bias of 2%, -26%, 25%, and 60%, respectively, and normalized mean error of 54%, 46%, 52%, and 73%, respectively. Comparison with the Monin-Obukhov similarity parameterization (MO) reveals that the UCPM significantly improves simulations of wind speeds in the UCL. Under neutral, stable, and unstable conditions, the normalized mean error of MO is 420%, 176%, and 184%, respectively, and UCPM is reduced to 78%, 52%, and 21%, respectively; at heights of 8, 15, 32, and 47 m within the UCL, the normalized mean error of MO is 283%, 184%, 227%, and 167%, respectively, and UCPM is reduced to 54%, 46%, 52%, and 73%, respectively.