Simulation of Aerosol Fields over South Asia Using CHIMERE - Part-II:Performance Evaluation

Abstract

In this paper, we evaluate the performance of the chemical transport model 'CHIMERE' over large Indian region (4-37.5N; 67-88.5E) for multiple years (2006, 2007 and 2008) by comparing the model simulations with concurrent aerosol measurements from different locations. Model simulated nearsurface black carbon mass concentrations agreed satisfactorily with measurements at various locations (oceanic, inland and island sites), in general, except during monsoon months, when the model underpredicted the measurements. Similar results were obtained when model simulated column integrated PM 10 mass concentrations were correlated with MODIS-derived aerosol optical depth (AOD), using AOD as a proxy for aerosol loading. The underperformance of the model during monsoon arises, at least partly, due to the model-simulated rainfall being higher than the actual rainfall over the Indian domain, during the monsoon season. Notwithstanding these, the general performance of the CHIMERE model to simulate aerosol loading over Indian domain during dry months is, in general, found to be satisfactory.

Evaluation of WRF-Chem-simulated meteorology and aerosols over northern India during the severe pollution episode of 2016

“…ERA5 data at a horizontal resolution of 0.25 • × 0.25 • are used for initializing the meteorology, boundary conditions and nudging in the model (Hersbach et al, 2020). Temperature, winds and water vapour are nudged towards ERA5 values above the planetary boundary layer (PBL) every 6 h, using grid nudging with a nudging coefficient of 6 × 10 −4 s −1 (Stauffer and Seaman, 1994). Terrestrial and land-use data are static and obtained from the MODIS IGBP 21-category land-cover classification (Friedl et al, 2002).…”

“…Modelling studies characterizing air pollution over India have utilized a variety of regional chemistry transport models (Nair et al, 2012;Kumar et al, 2012a, b;Moorthy et al, 2013;Pan et al, 2015;Srivastava et al, 2016;Schnell et al, 2018;Ghosh et al, 2023). These studies highlight various problems in simulating atmospheric composition over the Indian subcontinent, such as capturing the high aerosol loading, erroneous boundary-layer parameterizations, underestimations in emissions inventories, complex mountain topography and inaccurate moisture transport.…”