Work Package 4.2
This Work Package will apply an ensemble of leading atmospheric models (EMEP4Earth, WRFChem, MOZART, UKCA) for SA to assess the contribution of Nr emissions to particulate matter (PM), NO2 and NH3 concentrations and their human health impacts (drawing on published dose-response) and ecosystem impacts (WP3.1). Model assessment against existing networks (e.g. NPL-India, SAFAR) and new measurements will allow model application for abatement scenarios (WP1.2, 4.3, 4.4). Improvement of the measurement database will focus on the wider IGP, the world NH3 hotspot. A 10-site network for Nr measurement operated for 24 months from the IGP to the Himalayan foothills will deliver validation data and help elucidate the underlying chemical transformations. Utilizing EU EMEP experience, the hub will co-ordinate two multi-site campaigns of simultaneous highly time-resolved online aerosol composition by aerosol mass spectrometry (AMS), bringing together the AMS community active in SA. Inversions of satellite-derived NH3 and NOx data using WRFChem will be conducted to constrain the estimated emissions. With WP3.2, WP4.2 will monitor Nr levels at Himalayan forest sites, deploying high sensitivity NH3/NOx passive samplers and wet deposition measurements. The WP will deliver a better understanding of urban-rural sources of Nr, pollution maps and a validated basis to consider future N scenarios. Outputs will be complemented by training workshops to build South Asian capacity in low-cost atmospheric Nr sampling approaches developed at CEH.
Work package level Specific objectives
- To provide an improved understanding of NH3 sources and NH3/NH4+ dynamics across the IGP based on measurements, modelling and EO constraints
- To compile existing and generate new data for model evaluation across SA, using a combination of low-cost integrated samples and intensive campaigns based on AMS measurements
- To provide NH3 and SO2 concentrations and N/S wet deposition as well as meteorological measurements supported modelled fields at a high spatial resolution for WP3.1, including under scenarios
- To quantify concentration and deposition fields as well as Nr budget terms for SA, comparing 3 different models.
- To assess and improve model performance against existing and new measurement data (incl. providing feedback on emissions)
- To provide deposition for 30-year time-series for LTLS modelling and marine input
- To provide scenario calculations for the reference year (period), 2030 and 2050
- To quantify health impact caused by N emissions, incl. under abatement scenarios
- To compare NH3 measurement approaches and quantify potential artefacts in the methodologies currently used in S Asian networks (SAFAR, DRSNet-India)
- To establish low-cost measurement capability in SA
- To further spread chemistry and transport modelling (CTM) capability in SA
Work package level-specific questions
- What is causing the high NH3 concentrations observed by OA across the IGP? Can we reconcile ground-based observations, EO and model results?
- Source attribution of the Nr affecting Himalayan ecosystems? Country-to-country budgets?
- What is the exceedance of critical loads?
- How do Nr concentrations change across rural-urban, land use and altitude gradients?
- What is the contribution of NH3 derived particulates to urban PM and health impacts?
- How does this contrast with the contribution of NOx emissions to (urban) health impacts directly as harmful NO2 and indirectly as a precursor for O3 and PM?
- What is the relative importance of atmospheric deposition as nutrient input into coastal and marine water (via deposition to sea vs deposition to catchment)?
Work Package Leads:
- Nemitz (CEH)
- Beig (IITM)
- University of Edinburgh
- University of Bristol
- University of Kathmandu