TY - JOUR
T1 - Effect of radiation interaction and aerosol processes on ventilation and aerosol concentrations in a real urban neighbourhood in Helsinki
AU - Strömberg, Jani
AU - Li, Xiaoyu
AU - Kurppa, Mona
AU - Kuuluvainen, Heino
AU - Pirjola, Liisa
AU - Järvi, Leena
N1 - Funding Information:
We thank the Helsinki metropolitan region Urban Research programme, the Academy of Finland (CousCOUS project, decision numbers: 332177 and 332178), the Academy of Finland ACCC Flagship (decision numbers: 337549, 337552 and 337551) and the CITYZER project funded by Tekes and Finnish companies (decision number: 2883/31/2015). This project has also received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement nos. 101036245 (project RI-URBANS) and 101037319 (project PAUL). The authors are very grateful to Aleksi Malinen and Sami Kulovuori from the Metropolia University of Applied Sciences for the operation of the mobile laboratory Sniffer and to Aeromon Oy for conducting the drone measurements.
Funding Information:
This research has been supported by Tekes (grant no. 2883/31/2015), Horizon 2020 (grant nos. 101036245 and 101037319) and the Academy of Finland (grant nos. 332177, 332178, 337549, 337551 and 337552).Open-access funding was provided by the Helsinki University Library.
Publisher Copyright:
© 2023 Jani Strömberg et al.
PY - 2023/8/24
Y1 - 2023/8/24
N2 - Large-eddy simulation (LES) is an optimal tool to examine aerosol particle concentrations in detail within urban neighbourhoods. The concentrations are a complex result of local emissions, meteorology, aerosol processes and local mixing conditions due to thermal and mechanical effects. Despite this, most studies have focused on simplification of the affecting processes such as examining the impact of local mixing in idealised street canyons or treating aerosols as passive scalars. The aim of this study is to include all these processes into LES using the PALM model system and to examine the importance of radiative heating and aerosol processes in simulating local aerosol particle concentrations and different aerosol metrics within a realistic urban neighbourhood in Helsinki under morning rush hour with calm wind conditions. The model outputs are evaluated against mobile laboratory measurements of air temperature and total particle number concentration (Ntot) as well as drone measurements of lung-deposited surface area (LDSA). The inclusion of radiation interaction in LES has a significant impact on simulated near-surface temperatures in our study domain, increasing them on average from 8.6 to 12.4gC. The resulting enhanced ventilation reduces the pedestrian-level (4gm) Ntot by 53g%. The reduction in Ntot due to aerosol processes is smaller, only 18g%. Aerosol processes particularly impact the smallest particle range, whereas radiation interaction is more important in the larger particle range. The inclusion of radiation interaction reduces the bias between the modelled and mobile-laboratory-measured air temperatures from-3.9 to +0.2gC and Ntot from +98g% to-13g%. With both aerosol and radiation interaction on, the underestimation is 16g%, which might be due to overestimation of the ventilation. The results show how inclusion of radiative interaction is particularly important in simulating PM2.5, whereas aerosol processes are more important in simulating LDSA in this calm wind situation.
AB - Large-eddy simulation (LES) is an optimal tool to examine aerosol particle concentrations in detail within urban neighbourhoods. The concentrations are a complex result of local emissions, meteorology, aerosol processes and local mixing conditions due to thermal and mechanical effects. Despite this, most studies have focused on simplification of the affecting processes such as examining the impact of local mixing in idealised street canyons or treating aerosols as passive scalars. The aim of this study is to include all these processes into LES using the PALM model system and to examine the importance of radiative heating and aerosol processes in simulating local aerosol particle concentrations and different aerosol metrics within a realistic urban neighbourhood in Helsinki under morning rush hour with calm wind conditions. The model outputs are evaluated against mobile laboratory measurements of air temperature and total particle number concentration (Ntot) as well as drone measurements of lung-deposited surface area (LDSA). The inclusion of radiation interaction in LES has a significant impact on simulated near-surface temperatures in our study domain, increasing them on average from 8.6 to 12.4gC. The resulting enhanced ventilation reduces the pedestrian-level (4gm) Ntot by 53g%. The reduction in Ntot due to aerosol processes is smaller, only 18g%. Aerosol processes particularly impact the smallest particle range, whereas radiation interaction is more important in the larger particle range. The inclusion of radiation interaction reduces the bias between the modelled and mobile-laboratory-measured air temperatures from-3.9 to +0.2gC and Ntot from +98g% to-13g%. With both aerosol and radiation interaction on, the underestimation is 16g%, which might be due to overestimation of the ventilation. The results show how inclusion of radiative interaction is particularly important in simulating PM2.5, whereas aerosol processes are more important in simulating LDSA in this calm wind situation.
U2 - 10.5194/acp-23-9347-2023
DO - 10.5194/acp-23-9347-2023
M3 - Article
AN - SCOPUS:85172879750
SN - 1680-7316
VL - 23
SP - 9347
EP - 9364
JO - Atmospheric Chemistry and Physics
JF - Atmospheric Chemistry and Physics
IS - 16
ER -