RTCA Dr Paul Agnew - Met Office developments in air quality modelling

Transcript

1. OFFICIAL Met Office Developments in Air Quality Modelling Routes to Clean Air 21st October 2026 Paul Agnew Lucy Neal, Vivien Bright, Pedro Molina-Jimenez, Ben Drummond, Eleanor Smith, Florent Malavelle www.metoffice.gov.uk OFFICIAL © Crown Copyright 2017, Met Office
2. OFFICIAL What’s new at the Met Office? A period of major infra-structure change, including: • Move to new High Performance Supercomputer • Move to cloud-based computing facilities and data storage • A new weather forecast model coming • A new air quality model coming • Impact of AI on forecasting OFFICIAL
3. OFFICIAL Clean Air: Reanalysis Extension – Eleanor Smith Air quality reanalysis A gridded dataset giving concentrations of pollutants over the whole UK for every hour starting in 2003-2019 Reanalysis Data The reanalysis combines model output with observations to give … Coverage of the whole of the UK Hourly time resolution for a long time period Update: A supplementary dataset – ‘Interim Reanalysis’ for 2020 – 2025 – covering the Covid lockdown periods Consistency in model configuration and input data Inclusion of all species of interest Enhanced data over just model output alone by incorporating observations through a bias correction method paul.agnew@metoffice.gov.uk eleanor.smith@metoffice.gov.uk www.metoffice.gov.uk OFFICIAL © Crown Copyright 2024, Met Office
4. OFFICIAL AQ Reanalysis available on CEDA OFFICIAL
5. Air Quality Data Portal the data portal provides publicly available website the data portal toolkit can be used to search and extract data for specific locations and time periods Exeter 5 VO C Met Devon 200 4 PM2. NO 2 UK 2 O3 to air quality data via a England SO PM10 easy access meteorolog y Office 201 4 and calculate averages and statistics the portal provides as well as signposting other air quality information and data and resources communication data can be downloaded for offline investigation or the apps on the data portal can be used for a wide range of analysis … mapping mod el 23:0 0 Esri software comparisons of time periods, locations or datasets − + timeseries and long-term trends 200 3 201 9 concentration observations 00:00 built with 2003 vs 2019 concentration concentration articles for diurnal and seasonal cycles Ja De
6. OFFICIAL AQDP Update: March 2026 OFFICIAL
7. OFFICIAL NU-AQ: NAME-UKCA Air Quality model NU-AQ (“new-AQ”) (NAME-UKCA Air Quality model) Boundary conditions CAMS Composition Forecast (C-IFS) Emissions Offline: NAEI, ENTEC, EMEP, etc Online: UKCA … Some Features: • More flexible emissions and data output framework • Potential to combine Lagrangian-Eulerian modelling • Improved ability for point source representation • More sophisticated aerosol modelling • Particle mass and number • Improved representation of coarse component aerosol www.metoffice.gov.uk OFFICIAL © Crown Copyright 2017, Met Office
8. OFFICIAL NU-AQ: Status • Major components mostly in place • Implementation of improved photolysis in progress Current model NU-AQ OFFICIAL • Model showing good performance • Currently evaluating higher resolution configurations (2 and 4km) • Implementation currently planned for mid-2028
9. OFFICIAL NAME pollen forecast • Model based, to replace manual expert driven forecast • Uses NAME to model emission, transport and removal of pollen grains • Taxa specific: Alder, Hazel, Ash, Birch, Oak, Plane, Grass, Nettle, • 5 km gridded, hourly forecast • January – October – extends season to include earlier taxa Birch Oak Nettle Daily Pollen Level 11/6/2025 PWS • Pollen reanalysis • Will provide gridded hourly pollen fields across UK for 2000-2025 • Important for health research OFFICIAL Grass Lucy Neal and Katie Brown NAME
10. OFFICIAL Model accounts for Short-term biometeorology Wind Rainfall Increases emissions Wind speed & w*, (convective velocity scale) Reduces emissions No emissions > 0.5mm/hr Diurnal factor Taxa specific Vapour pressure deficit Calculated from temperature and relative humidity, taxa specific OFFICIAL Lucy Neal and Katie Brown
11. OFFICIAL Smoke reaching Aberdeen on 24th July 2026 BBC photo OFFICIAL
12. OFFICIAL PM in Aberdeen on 24th July 2026 Plot generated by Air Quality Scotland site OFFICIAL
13. OFFICIAL How are wildfires handled in the forecast? Global Fire Assimilation System (GFAS) • Hotspot detection • Wildfire emissions estimates included in forecast • However significant latency in availability OFFICIAL
14. OFFICIAL Wildfire in the AQ Forecast: Cairngorms 24th July High pollution measured in Aberdeen OFFICIAL
15. OFFICIAL Wildfire in the AQ Forecast: Cairngorms 26th July OFFICIAL
16. OFFICIAL Wildfire in the AQ Forecast: Cairngorms 27th July OFFICIAL
17. OFFICIAL Can we better handle wildfire pollution? • Latency of satellite data can be improved – somewhat; however… • Wildfires constitute a rapidly evolving pollution source • Very different to the situation modelled by ‘routine air quality’ • Need more timely, accurate emission information • A Daily Air Quality Index is not well-suited to this rapid source evolution • Simply updating the DAQI forecast more frequently is not helpful and could be harmful (misleading) • Needs a different approach: we will be actively working on this, in collaboration with stakeholders… OFFICIAL
18. OFFICIAL Estimating Exposure • Exposure depends on: • Ambient pollution levels at the location of the individual • Rate of air intake and volume of air inhaled for a specified duration • This will depend on activity • “Ambient pollution levels at the location of the individual” • To estimate this accurately requires detailed knowledge of where the individual is and what the ambient pollution levels are • Home, travelling, work, elsewhere • State-of-the-art approach developed under the UKRI Clean Air project by M. L. Thomas et al., "A Data Integration Approach to Estimating Personal Exposures to Air Pollution," 2022 IEEE International Conference on Big Data (Big Data), Osaka, Japan, 2022, pp. 4551-4559, doi: 10.1109/BigData55660.2022.10020701 OFFICIAL
19. OFFICIAL Air pollution in a box: Limit analysis to PM Outside pollution air concentration Co Fraction of box volume of air exchanged per second: Vf,ex Inside pollution air concentration Ci Sources per unit vol: SV,em OFFICIAL Loss by deposition deposition velocity approach: vdd Ci   is the total area for particle deposition per unit volume Indoors particles can be removed by any surface, not just the lower boundary (unlike CTM)
20. OFFICIAL Air pollution in an empty box 𝑑𝐶𝑖 = 𝑉𝑓,𝑒𝑥 𝐶𝑜 − 𝑉𝑓,𝑒𝑥 + 𝑣𝑑𝑑 Ω 𝐶𝑖 𝑑𝑡 Solution with Ci(0)=0 and no internal sources 𝑉𝑓,𝑒𝑥 𝐶𝑖 = 1 − 𝑒 − 𝑉𝑓,𝑒𝑥 +𝑣𝑑𝑑 Ω 𝑡 𝐶𝑜 𝑉𝑓,𝑒𝑥 + 𝑣𝑑𝑑 Ω Steady-state solution 𝑉𝑓,𝑒𝑥 𝐶𝑖 = 𝐶𝑜 𝑠𝑠 𝑉𝑓,𝑒𝑥 + 𝑣𝑑𝑑 Ω OFFICIAL
21. OFFICIAL Measured indoor deposition rates Size range (mm) Deposition rate (hr-1) 0.3 - 0.5 0.3 0.5 - 1.0 0.4 1.0 - 2.5 0.8 2.5 – 5 1.3 5 – 10 2.5 > 10 5.2 C. Howard-Reed et al., Deposition rates of fine and coarse particles in residential buildings, NISTR 7068, 2003 OFFICIAL
22. OFFICIAL Estimated ratio of indoor to outdoor pollution in steady state using indoors deposition rates OFFICIAL
23. OFFICIAL Some observations • In the steady state, indoor PM air concentrations can be up to factor 5 or more, lower than those outdoors • There is a rapid variation according to air exchange rates • Indoor deposition rates vary significantly according to particle size • This results in effectively ‘filtering’ the indoor air so that the fine fraction (smaller particles) come to dominate • The crucial, controlling parameter is the ratio k of the deposition loss rate to the air exchange rate OFFICIAL
24. OFFICIAL Some consequences for exposure modelling • Identical pollutant outside air concentrations can give rise to very different indoor personal exposure contributions • Outside of controlled studies, the air exchange rates for individuals are unknown. For modelling study groups it is necessary to average over an assumed distribution of values • This additional uncertainty is likely comparable to, or greater than, the spatial averaging which occurs in outdoors air quality models • We haven’t even attempted to account for uncertainty due to indoor sources… • The indoors shift of the particle size distribution resulting from sizedependent loss rates may be significant OFFICIAL
25. OFFICIAL Thank you for listening: Any Questions? www.metoffice.gov.uk OFFICIAL © Crown Copyright 2017, Met Office