Aerosol Modulated Heat Stress in South Asia

There is mounting evidence that heatwaves are increasing in frequency and duration around the world. South Asia is highly vulnerable to heatwaves due to its high heat exposure and limited adaptive capacity. Besides, South Asia is also a global aerosol hotspot. Many governments in South Asia plan to reduce aerosol emissions. However, any change to aerosol concentrations may also modify heatwave characteristics through ‘direct’ influences on the radiation budget and surface heat fluxes, and through ‘indirect’ impacts, such as on cloud formation and atmospheric circulation. Hence, lowering aerosol concentrations – while good for human respiratory health – may increase heat stress.

Previous studies have shown that aerosols can affect heat stress by influencing temperature, humidity, wind speed and radiation. However, the process of how aerosols affect heat stress has not been explained in detail. Our research intends to reveal the specific process of aerosols affecting heat stress from the perspective of surface energy balance, using WRF model as the initial methods. Improving understanding of the mechanisms of aerosol influence on heatwaves will help improve the long-range prediction capability for extreme heat. The results from the research will also be of interest to policy makers and disaster risk reduction communities, as it will help characterize the evolving public health burden to expect as temperature rises and aerosol loadings change in the future.

Our preliminary results show that the presence or absence of aerosol emissions affects surface temperature, 2-m temperature, and sensible heat flux in South Asia, with different patterns being observed during the daytime and nighttime.