Mesoscale atmospheric circulations play an important role in the transport of air pollution and local air quality issues. The planetary boundary layer (PBL), the thermo-dynamical structure and the flow field play an important role in air pollution dispersion. Hence, the PBL parameters over Nagpur, India are simulated using the ARW v. 3.6.1 mesoscale model. High-resolution simulations are conducted with triple nested domains having a horizontal resolution of 27, 9 and 3 km, as well as 27 vertical levels by using the 1 . 1º NCEP Final Analysis meteorological fields for initial and boundary conditions. Eight fair-weather days in winter and summer (January and April 2009) with no significant synoptic activity were chosen for the study. Sensitivity experiments of the ARW model were conducted with two non-local (Yonsei University [YSU], and Asymmetric Convective Model v. 2 [ACM2]) and three local turbulence kinetic energy (TKE) closure (Mellor-Yamada Nakanishi and Niino Level 2.5 PBL [MYNN2], Mellor-Yamada-Janjic [MYJ], and quasi-normal scale elimination [QNSE]) turbulence diffusion parameterizations, to study the evolution of PBL parameters and the thermodynamical structure during the study period. After validation of the simulated parameters with the available in-situ data, it was revealed that the non-local PBL scheme YSU, followed by local scheme MYNN2, could able to capture the characteristic variations of surface meteorological variables and the thermodynamical structure of the atmosphere. The present results suggest that the PBL schemes, namely YSU and MYNN2, performed better in representing the boundary-layer parameters and are useful for air pollution dispersion studies.

An attempt has been made to develop a pre-processor coupler for offline coupling of atmospheric mesoscale model (WRF) with a dispersion model (AERMOD) to estimate the ground level concentrations due to industrial sources over a coastal city, Visakhapatnam, India. To integrate AERMOD in standalone mode, surface and upper meteorological observations and various planetary boundary layer (PBL) parameters with good temporal resolution are required, that are absent for most locations in India. We have developed an integrated WRF-AERMOD modeling system that gets required PBL parameters the pre-processor coupler. Using this model, evaluation of the dispersion of nitrogen oxides (NOX) over Visakhapatnam during summer month with emission inventory of elevated point sources of various industries is conducted. Sensitivity studies of PBL schemes of WRF after validation reveal that the non-local schemes, Yonsei University (YSU) followed by Asymmetric Convective Model version 2 (ACM2), captured well the characteristic variations of surface meteorological variables, vertical atmospheric structure. After validating with monitored air quality data, it is found that the integrated model with YSU followed by ACM2 is good in simulating ground level concentrations of NOX. The present work advocates that the developed modeling system is useful for better assessment of pollution dispersion over coastal regions.

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