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A collaboration between NERC CityFlux and REPARTEE

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A collaboration between NERC CityFlux and REPARTEE

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  1. REPARTEE: Pollutant FluxesEiko Nemitz, Gavin Phillips, Chiara Di Marco, Daniela Famulari, Carole Helfter, Rick Thomas, David Fowler: Centre for Ecology and Hydrology (CEH) EdinburghClaire Martin, James Dorsey, Martin Gallagher: SEAES, University of ManchesterBen Langford, Brian Davison, Nick Hewitt: University of LancasterJanet Barlow, Curtis Wood: University of ReadingSue Grimmond:Kings College London A collaboration between NERC CityFlux and REPARTEE

  2. Urban Flux Measurement Campaigns within CityFlux June 2003 Boulder, CO(92,000) CityFluxDecember 2005 Edinburgh(435,000) GOTE2005Feb. 2005 Gothenburg(480,000) CityFluxMay 2006 Manchester (2,200,000) MIRAGEMarch 2006 Mexico City (19,200,000) CityFluxOctober 2006 London(7,500,000)

  3. Direct measurement of emissions (unlike emissions derived from concentrations) Independent top-down verification of emission inventories (non reactive compounds) Source attribution (spatial & temporal) Identification of unknown sources Information on chemical processing (reactive compounds) Why Measure Urban Pollutant Fluxes?

  4. Application of eddy covariance approach to the urban environment (like CO2 forest flux towers in international networks) Derives vertical flux through the horizontal plane at measurement height Flux footprint averages over several km2 Micrometeorological Flux Measurement

  5. Eddy Covariance Need a rapid (5 -10 Hz) measurement of concentration and wind components up-draughts down-draughts

  6. Eddy-covariance fluxes: CO2 (18 months) CO Volatile organic compounds (VOCs) – benzene, toluene, methanol, acetone, isoprene, … Particle Number (total, size-segregated) Aerosol Chemical Components (NO3-, SO42-, Org) Ozone (REPARTEE-I only) Gradients (BT Tower vs. Regents Park): Further aerosol components O3, NO, NO2, SO2 Flux Measurements During REPARTEE

  7. Gradients above London (REPARTEE-I) How representative is the Park of the average concentration at ground level?

  8. Fluxes of CO2 and H2O(average diurnal cycles) • 1. Lower CO2 net emissions in summer: • No heating related emissions • Net CO2 uptake by biosphere (parks, gardens) • 2. Largest night-time emissions in winter, followed by spring • Highest heating related emissions

  9. Weekday vs. Weekend

  10. Source Attribution of Net CO2 Flux

  11. Comparison of VOC Fluxes with NAEI

  12. Diurnal Cyclesduring REPARTEE-II

  13. Particle Number Fluxes by CPC(10 – 2000 nm)

  14. Variability in Particle Number Flux

  15. PMF Factor Analysisof Organic Aerosol (BT Tower) LV-OOA-91? HOA LV-OOA “Cooking” OA Consistent with Regents Park measurements during REPARTEE: Allan et al., ACP, 2010.

  16. Q-AMS Fluxes (REPARTEE-I 2006) Traffic HOA CO Nitrate Sulfate LV-OOA Concentrations Fluxes

  17. Correlation between HOA and CO Fluxes (REPARTEE-I, Q-AMS) Look out for: Phillips et al. in ACPD REPARTEE Special Issue

  18. Comparison with Other CitiesDiurnal Cycles NO3- & HOA

  19. Comparison of Concentration vs. Flux Spectrum m/z

  20. Exchange velocities (Campaign Average)Ve = Flux / Concentration C4H7++ C3H3O+ C5H7++ C4H3O+ NO2+ SO+ SO2+ C4H9+ CO2+

  21. First independent assessment of emission inventories through direct flux measurements for London Close agreement between measurements and NAEI for CO2, CO and some VOCs (benzene / toluene) Poor agreement for other oxygenated VOCs Aerosol composition and diurnal pattern in organic aerosol fluxes consistent with significant contribution from cooking (deep frying?) Urban area acts as a significant source for aerosol nitrate during certain conditions (cool, calm, high humdity) Flux measurements provide a further angle to probe chemical signature of local (primary) organic aerosol (ongoing). Take-Home Messages

  22. Full publication in Atmos. Chem. Phys. REPARTEE Special Issue (online) ClearfLo long-term flux measurements 2010-2013: CO CO2 CH4 (first time) O3 NO/NO2 (first time) Particle number Outlook

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