| dc.description.abstract | Air pollution is an ongoing worldwide problem especially for developing countries. In South Asia, Future projection has shown potentially no slow-down of enhanced emissions (RCP 8.5), while meteorology, a factor may help regulate the local pollution levels, tends to change in the future as well. We identified three key variables: U10, T200 and PBLH that are highly correlated with local pollution levels in India and constructed Hazy Weather Index for India (HWII). HWII helps build a statistical projection model to evaluate the contribution from climate change side. The results suggest that a more favorable atmospheric environment is expected for pollution dispersion in the future, however, such condition is likely to be overwhelmed by enhanced emissions.
In addition to air pollution, heat has raised great concerns in public health field. Based on a model simulation, here we show that when daily average wet-bulb temperature of 25 °C is taken as the threshold for severe health impacts, heat extremes frequency averaged over South Asia increases from 45 days/year in 1997–2004 to 78 days/year in 2046–2054 under RCP8.5 scenario. Even more concerning is the joint occurrence of the heatwave and high-PM hazard (HHH), which would have substantial increases of 175% in frequency and 79% in duration. The alarming increases in just a few decades pose great challenges to adaptation and call for more aggressive mitigation.
Simulations above were conducted using MOZART-MOSAIC chemistry module. Despite being a comprehensive chemistry suite, MOZART-MOSAIC simulations are computationally expensive, making a large area resolution simulation less practical. A modal aerosol module with three lognormal modes (MAM3) was developed by Ma et al., (2014) but suffers two major deficiencies: (1) the biomass burning emission is ignored and (2) no mechanism that converts VOC to SOA. We perform six simulations (WRF-CAM5) to show progressive improvements in the model against various validation benchmarks.
We tested our updated WRF-CAM5 for cloud-aerosol interactions off the US west coast. We show that the aerosol compositions and distributions play a significant role in regulating the cloud fraction and effective radius in the region. | en |
