19 Dec 2023Street-scale pollution maps for Ireland now available

Results from CERC's modelling of street-scale air pollution in Ireland have been published as part of the Irish Environmental Protection Agency (EPA) report 'Air quality in Ireland 2022'. The full CERC report with high-resolution maps for a wider range of regulated air pollutants is also available. The predicted concentrations were evaluated with measured concentrations with generally good performance for both years at all site types, meeting the FAIRMODE model quality objectives. Modelled concentrations were compared to current Irish air quality standards air quality standards, with exceedances generally associated with the major road network. Most of Ireland meets the World Health Organisation (WHO) guideline for annual average NO₂ concentrations, with exceedences in urban areas, while a substantial proportion of Ireland does not meet the lowest guideline for annual average PM_2.5 concentrations.

CERC were commissioned by the Irish EPA to provide street-scale modelling of Ireland for 2018 and 2019. This used the Multi-model Air Quality System (MAQS) coupled system (developed by CERC) to link regional scale hourly pollution predictions from the EMEP model with local ADMS-Urban modelling. The UK Centre for Ecology & Hydrology (UK CEH) ran the WRF mesoscale meteorological model and EMEP chemical transport model with 1 km horizontal grid resolution over Ireland. CERC carried out detailed road traffic emissions calculations in EMIT based on traffic flow data supplied by the National Transport Authority (NTA) and Transport Infrastructure Ireland (TII). Gridded emissions from non-traffic sources were obtained from the MapEire inventory.

Street canyon effects on dispersion were included in major urban areas. Three major road tunnels were also included in the modelling using the ADMS-Urban tunnels module, with high concentrations noticeable around the portals of the Dublin Port tunnel. The model output is at hourly temporal resolution and irregular spatial resolution. The MAQS PostProcessor utility was used to calculate annual average and high percentile hourly concentrations on regular grids for plotting, at 20 m resolution for whole country maps and 5 m resolution for individual cities.

The 2019 mapped concentrations were uploaded to the recent FAIRMODE composite mapping exercise, which combines and assesses modelling results for different parts of Europe. Preliminary results from this exercise were presented in October 2023, with CERC's modelling results showing good performance in the 'high resolution, unassimilated' category. Presentations describing the Irish emissions inventory development and coupled system modelling were given by CERC at the 2023 ADMS-Urban and ADMS-Roads User Group Meeting.

18 Dec 2023Review of methods for monitoring and modelling air quality

CERC recently contributed modelling expertise to a comprehensive Environment Agency (EA) report that reviewed methods for air quality monitoring and modelling, and their integration. The report examines both well-established techniques already employed by the EA, such as Gaussian plume dispersion for air quality modelling, and emerging technologies, such as data assimilation and machine learning for integration. Factors such as spatial-temporal resolution, cost considerations, the maturity of the technique, and requisite user expertise are evaluated. The report provides practical recommendations on the suitability of different air quality assessment techniques for EA requirements, including their regulatory responsibilities.

The report is a significant collaborative effort engaging experts across governmental, industrial and academic sectors, with specialist knowledge in emission measurements, air quality measurements, and modelling – many thanks to AQC, Aether and all involved! It offers valuable insight for those interested in the rapidly evolving landscape of air quality techniques.

12 Dec 20232023 ADMS User Group Meetings – presentations are available to download

Following this year’s ADMS User Group Meetings, which took place in York on 29-30 November, electronic copies of the presentations are now available to download from the CERC website User Area. Model users with a valid support contract, including all annual licence holders, are entitled to register for password-protected access to the User Area. To register, or to be reminded of your password, click here.

6 Dec 2023Estimating emissions from concentration measurements: inverse dispersion modelling report published

The Environment Agency recently commissioned CERC and AQC to investigate inverse dispersion modelling methods which could be applied to fugitive (uncontrolled) sources of methane. Inverse dispersion modelling methods allow the estimation of unknown emission rates from concentration measurements. Improving estimates of methane emissions from sources such as landfill sites is important for quantifying greenhouse gas impacts.

The report from this project has now been published online. It includes: a literature review of different inverse dispersion modelling methods; an assessment of the applicability of inverse dispersion modelling methods to different EA-regulated facilities; a study testing four inverse dispersion modelling methods with measurements from three landfill sites; and recommendations for future use of inverse dispersion modelling.

CERC have previously developed and implemented an inverse dispersion modelling approach for improving estimates of urban emissions. For this project we developed a new 'modified Bayesian' inverse modelling technique, due to the short timescale of the plume transect measurements. Measurements at 1 second intervals capture the instantaneous rather than ensemble plume. The concentration fluctuations module in ADMS was used to represent the short-term distribution of concentrations, with inverse modelling applied to the peak modelled and measured concentrations only.

The image shows an example of transect measurements of acetylene (C2H2) tracer gas. The 1 second measured data displays a narrow peak, while standard modelling ('modelled') predicts a wider plume with a lower peak concentration. The maximum model prediction of 1 second concentrations from the fluctuations module ('modelled fluctuations maximum', also showing standard deviation error bars) gives good agreement with the peak measurement. Methane measurements from the same transect were used in the inverse modelling study.

5 Dec 2023PhD Opportunity to Explore the Pollution-Climate-Health Dilemma

CERC is a partner for a PhD studentship harnessing data and air pollution modelling to examine the complex interactions between pollution, climate, and health. The PhD project will delve into the issue of why the public is perceiving a decline in their health and wellbeing due to exposure to air pollutants when, in reality, anthropogenic air pollution emissions have significantly decreased over the last 30 years. One potential factor contributing to this dilemma could be the influence of climate change and the evolving nature of emissions.

The studentship will be awarded by Envision, a doctoral training program which fosters collaboration between researchers, industry partners and NGOs to cultivate a new generation of exceptional environmental scientists. The selected student will benefit from supervision of a team of interdisciplinary experts throughout the PhD journey, including an NHS clinician, and receive training from CERC and RDScientific.

If this rewarding and challenging project appeals to you please consider applying here. Or for further details please contact Professor Sarah Metcalfe, sarah.metcalfe@nottingham.ac.uk or Professor Duncan Whyatt, d.whyatt@lancaster.ac.uk.