EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

High-resolution dynamical downscaling of present and future air quality over the South Asia-Cordex domain with a focus on the megacity Delhi, India

Ummugulsum Alyuz1, Ranjeet Sokhi1, Kester Momoh1, Vikas Singh2, Chandra Venkataraman3, Arushi Sharma3, Ganesh Gupta3, Kushal Tibrewal3, Ravindra Khaiwal4, Suman Mor5, Gufran Beig6, and the PROMOTE Team*
Ummugulsum Alyuz et al.
  • 1University of Hertfordshire, UK
  • 2National Atmospheric Research Laboratory, Gadanki, Andhra Pradesh, India
  • 3Indian Institute of Technology Bombay, India
  • 4Post Graduate Institute of Medical Education & Research (PGIMER), Chandigarh. India
  • 5Panjab University, Chandigarh, India
  • 6National Institute of Advanced Studies (NIAS), Indian Institute of Science (IISc) Campus, Bangalore, India
  • *A full list of authors appears at the end of the abstract

Through a NERC/MOES funded project, PROMOTE, analysis based on WRF and CMAQ models has been conducted to understand the impact of road transport emissions on air quality over Delhi. NCEP/FNL 1 data was used to drive WRF with four nested domains over India with resolutions of 45km, 15 km, 5 km, and 1.6 km for 2018. EDGAR v5.0 emission inventory (for 2015) 2 and Cam-Chem initial and boundary condition data 3 were used to drive the CMAQ model. In the baseline runs, all domains were considered without any change in emissions, while in Scenario 1, road transport sector was removed in the third domain (5km) covering Delhi region. Model performance for NOx, NO2, PM10, PM2.5 and O3 was evaluated with available observations, recognising that air quality and meteorological datasets were limited for the period analysed. In the later part of the study, OSCAR model 4 was used to predict the high-resolution air quality over Delhi and estimate the contributions from road transport emissions. Relative contributions to Delhi's air quality from local and regional long range transport sources are discussed. 

As part of a NERC funded COP26 project on Climate Adaptation for India, an overarching goal of this study is to quantify how air quality changes in South Asia in a changing climate under SSP245 (middle-of-the-road scenario) 5. A dynamical downscaling process was implemented and bias-corrected Coupled Model Intercomparison Project Phase 6 (CMIP6) data 6 was used to drive Weather Research and Forecasting (WRF) model simulations. Simulations have been conducted for the South Asia-Cordex domain for 2015 (representative of 2011-2020 years) and 2050 (representative of 2046-2055 years) with a 27 km grid resolution. The Community Multiscale Air Quality (CMAQ) model was driven with an average of ten years meteorology with future land use land cover, initial and boundary conditions, and future emissions 7 for India. To assess the impact of averaged meteorology on the CMAQ performance, the CMAQ model was run with both ten years' averaged meteorology around 2015 (2011-2020) and only 2015 meteorology.

Although averaging ten years around the desired year suppresses the diurnal variations, it provides an indication of monthly changes in climate and air quality variables. Under the selected SSP245 scenario, the CMAQ model predicted monthly means of PM2.5 anomalies (2050-2015) range over India between 8 to 41 μg/m3. Significant change is PM2.5, PM10, NOx, and O3 anomalies, especially in the urban regions of India, such as Delhi, before and after the Monsoon months (June to October) have been observed.

Financial Support: We acknowledge funding from NERC/MOES (Reference: NE/P016391/1) for the PROMOTE project and NERC funding (Reference: 2021COPA&R48Sokhi) for the COP26 Improving adaptation strategies for climate extremes and air pollution affecting India project.


1 NCEP/NOAA/U.S. 2015,

2 Crippa M. et al. (2019):

3 Buchholz, R. R. et al, (2019).

Singh V, et al. (2020) Environmental Pollution, 257, 113623

5 van Vuuren, D.P. et al. (2011). Climatic Change 109, 5.

6 Xu, Z. et al.  (2021). Sci Data 8, 293.

7 SMoG-India v1 2015 and 2050 emissions dataset, NERC project.



How to cite: Alyuz, U., Sokhi, R., Momoh, K., Singh, V., Venkataraman, C., Sharma, A., Gupta, G., Tibrewal, K., Khaiwal, R., Mor, S., and Beig, G. and the PROMOTE Team: High-resolution dynamical downscaling of present and future air quality over the South Asia-Cordex domain with a focus on the megacity Delhi, India, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-17561,, 2023.

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