3:45 PM - 4:00 PM
[HCG26-07] Numerical analysis of PM pollution after Kharif-crop harvest over the Delhi-Haryana-Punjab region by combining regional model simulations and field observations
Keywords:PM2.5 pollution, regional air quality model, WRF/CMAQ, dry season over north-west India, crop residue burning
The remarkable increase in air pollution over the megacities of South Asia has attracted worldwide attention. Compared to the recommendation for PM2.5, e.g. 25 μgm-3 24-hour average, in the World Health Organization's Air Quality Guidelines (AQGs) or that of the Indian government (~60 μgm-3), the PM2.5 concentration level in the National Capital Region (NCR) of Delhi, India is significantly higher. Especially during the dry season after the kharif crop harvest, from October to February, pollution levels tend to be worse over the Delhi NCR and its environs, which is believed to be affected by seasonally increased anthropogenic emissions, such as post-harvest burning of straw stubble over the extensive grain-growing region of northwestern India, in addition to the stagnation of atmospheric pollutants due to meteorological conditions.
The AAKASH project has conducted intensive field campaigns using Compact and Useful PM2.5 Instrument with Gas Sensors (CUPI-Gs) in the states of Punjab, Haryana and Delhi NCR from September to November 2022 and 2023. These campaigns were found to increase PM2.5 concentrations above 400 µgm3 in Delhi NCR, and during this time, the polluted air masses influenced by the Crop Residue Burning (CRB) were expected to be transported from Punjab to Haryana and Delhi.
A regional air quality modeling system using WRF/CMAQ incorporating emission inventories, HTAPv2.1, and GFASv2.1 seemed reasonable enough to simulate PM2.5 concentrations in the Delhi-Haryana-Punjab region except during the early dry season, October to November. For the early dry season, the modeling system tends to underestimate observed PM2.5 concentrations. The modeled sensitivity experiments for CRB emissions somehow explained the PM2.5 underestimations by the model in Punjab. One of the remaining issues in the PM2.5 simulation would be uncertainties in the emissions, especially related to small-scale post-harvest straw stubble burning and other unknown emission sources. The other problems would also be inherent in some mechanisms of the model during air mass transport. After presenting the current status of the air quality model, the spatial and temporal variations of post-harvest air pollutants over the Delhi-Haryana-Punjab region will be discussed.
[Acknowledgements]
This research is financially supported by Research Institute for Humanity and Nature (RIHN: a constituent member of NIHU) Project No. 14200133 (Aakash). The intensive field campaigns were conducted with supports from all participants of the network observations in Aakash project.
The AAKASH project has conducted intensive field campaigns using Compact and Useful PM2.5 Instrument with Gas Sensors (CUPI-Gs) in the states of Punjab, Haryana and Delhi NCR from September to November 2022 and 2023. These campaigns were found to increase PM2.5 concentrations above 400 µgm3 in Delhi NCR, and during this time, the polluted air masses influenced by the Crop Residue Burning (CRB) were expected to be transported from Punjab to Haryana and Delhi.
A regional air quality modeling system using WRF/CMAQ incorporating emission inventories, HTAPv2.1, and GFASv2.1 seemed reasonable enough to simulate PM2.5 concentrations in the Delhi-Haryana-Punjab region except during the early dry season, October to November. For the early dry season, the modeling system tends to underestimate observed PM2.5 concentrations. The modeled sensitivity experiments for CRB emissions somehow explained the PM2.5 underestimations by the model in Punjab. One of the remaining issues in the PM2.5 simulation would be uncertainties in the emissions, especially related to small-scale post-harvest straw stubble burning and other unknown emission sources. The other problems would also be inherent in some mechanisms of the model during air mass transport. After presenting the current status of the air quality model, the spatial and temporal variations of post-harvest air pollutants over the Delhi-Haryana-Punjab region will be discussed.
[Acknowledgements]
This research is financially supported by Research Institute for Humanity and Nature (RIHN: a constituent member of NIHU) Project No. 14200133 (Aakash). The intensive field campaigns were conducted with supports from all participants of the network observations in Aakash project.