Impact of Emission Mitigation on Ozone-Induced Wheat and Rice Damage in India

In this study, we evaluate the potential impact of ground level ozone (O₃) on rice and wheat yield in top 10 states in India during 2005. This study is based on simulated hourly O₃ concentration from the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem), district-wise seasonal crop production datasets and accumulated daytime hourly O₃ concentration over a threshold of 40 ppbv (AOT40) indices to estimate crop yield damage resulting from ambient O₃ exposure. The response of nitrogen oxides (NO_x) and volatile organic compounds (VOC) mitigation action is evaluated based on ground level O₃ simulations with individual reduction in anthropogenic NO_x and VOC emissions over the Indian domain. The total loss of wheat and rice from top 10 producing states in India is estimated to be 2.2 million tonnes (3.3%) and 2.05 million tonnes (2.5%) respectively. Sensitivity model study reveals relatively 93% decrease in O₃-induced crop yield losses in response to anthropogenic NO_x emission mitigation. The response of VOC mitigation action results in relatively small changes of about 24% decrease in O₃-induced crop yield losses, suggesting NO_x as a key pollutant for mitigation. VOC also contribute to crop yield reduction but their effects are a distant second compared to NO_x effects.