A098-02
Assessment of changes in source apportionment of PM2.5 and in emissions of NOx from ground based measurements and time series forecasting of NO2 concentrations in the UK
Thursday, 10 December 2020: 07:04
Virtual
Hugh Coe1, David O Topping2, James D Allan3, M. Rami Rami Alfarra4, Tong Wu5, Saleh Alzahrani5, Ernesto Villegas6, Khalid Alzahrani4, Jonathan Taylor7, Nicholas Anthony Marsden1, Hugo Ricketts7, Zainab Bibi5, Michael Flynn8 and Gordon McFiggans7, (1)University of Manchester, School of Earth and Environmental Sciences, Manchester, M13, United Kingdom, (2)University of Manchester, School of Earth, Atmospheric and Environmental Science, Manchester, United Kingdom, (3)Department of Earth and Environmental Sciences, The University of Manchester, Manchester, United Kingdom, (4)Department of Earth and Environmental Sciences, The University of Manchester, Manchester, UK, Manchester, United Kingdom, (5)University of Manchester, DEES, Manchester, United Kingdom, (6)University of Manchester, School of Earth, Atmospheric and Environmental Sciences, Manchester, United Kingdom, (7)University of Manchester, Manchester, United Kingdom, (8)University of Manchester, School of Earth and Environmental Sciences, Manchester, United Kingdom
Abstract:
To slow transmission of COVID-19 during the recent epidemic stringent travel restrictions and stay at home orders were instigated in the UK as in many other countries. The stay at home orders began on 23
rd March 2020 and continued until May 10
th 2020 when easing of restrictions began incrementally. These restrictions provided a unique opportunity to examine changes in the source contribution to PM2.5 of different sectors and assess changes in NO
x concentrations using an extensively instrumented ground based measurement station as well as a network of air quality measurement sites from across Manchester.
We show that substantial changes in meteorology before and during the stay at home order had a substantial influence on pollution, as a result we caution against using simple time series analyses to diagnose effects of a change in emissions. Air mass categorisation shows that while NOx was reduced in all air masses compared to the pre-stay at home orders, PM2.5 reductions were not readily detectable. We show that secondary particulate is a major contribution to PM2.5 during periods of flow from the south and east and that concentrations were not significantly reduced compared to the average values observed in these air masses. We expect this to be representative of much of the UK in these conditions due to the regional nature of secondary PM.
We did not detect any noticeable change in the absolute concentration of black carbon as a result of the stay at home order. We do show that there is a reduction in daytime black carbon from road traffic but this is compensated for by an increase in wood burning. We will present a source apportionment study of PM2.5 based on ACSM and XACT data.
Lastly, we show the utility of the Facebook Prophet model in forecasting concentrations of NO2 at individual air quality measurement stations and use this to examine the effect of traffic volumes and sector contributions to NO2 at roadside and urban background locations.
