Abstract

Vertical profiling of aerosol particles was performed during the PANhellenic infrastructure for Atmospheric Composition and climatE chAnge (PANACEA) winter campaign (10 January 2020–7 February 2020) over the city of Ioannina, Greece (39.65° N, 20.85° E, 500 m a.s.l.). The middle-sized city of Ioannina suffers from wintertime air pollution episodes due to biomass burning (BB) domestic heating activities. The lidar technique was applied during the PANACEA winter campaign on Ioannina city, to fill the gap of knowledge of the spatio-temporal evolution of the vertical mixing of the particles occurring during these winter-time air pollution episodes. During this campaign the mobile single-wavelength (532 nm) depolarization Aerosol lIdAr System (AIAS) was used to measure the spatio-temporal evolution of the aerosols’ vertical profiles within the Planetary Boundary Layer (PBL) and the lower free troposphere (LFT; up to 4 km height a.s.l.). AIAS performed almost continuous lidar measurements from morning to late evening hours (typically from 07:00 to 19:00 UTC), under cloud-free conditions, to provide the vertical profiles of the aerosol backscatter coefficient (baer) and the particle linear depolarization ratio (PLDR), both at 532 nm. In this study we emphasized on the vertical profiling of very fresh (~hours) biomass burning (BB) particles originating from local domestic heating activities in the area. In total, 33 out of 34 aerosol layers in the lower free troposphere were characterized as fresh biomass burning ones of local origin, showing a mean particle linear depolarization value of 0.04 ± 0.02 with a range of 0.01 to 0.09 (532 nm) in a height region 1.21–2.23 km a.s.l. To corroborate our findings, we used in situ data, particulate matter (PM) concentrations (PM2.5) from a particulate sensor located close to our station, and the total black carbon (BC) concentrations along with the respective contribution of the fossil fuel (BCff) and biomass/wood burning (BCwb) from the Aethalometer. The PM2.5 mass concentrations ranged from 5.6 to 175.7 μg/m3, while the wood burning emissions from residential heating were increasing during the evening hours, with decreasing temperatures. The BCwb concentrations ranged from 0.5 to 17.5 μg/m3, with an extremely high mean contribution of BCwb equal to 85.4%, which in some cases during night-time reached up to 100% during the studied period.

Highlights

  • Wildfires, agricultural fires, and the use of wood as fuel for domestic heating during the winter season, are the major sources of the biomass burning (BB) particles [1,2,3]

  • The local emissions of BB related particles may have led to a sharp increase in the intensity of air pollution episodes during cold winter periods, especially under specific meteorological conditions within a shallow Planetary Boundary Layer (PBL) as discussed by Kassomenos et al (2003) and Sindosi et al (2003, 2019, 2021) [10,11,12,13]

  • Despite the severity of these air particulate pollution episodes occurring during winter-time, there has been a lack of knowledge of the spatio-temporal evolution of the vertical mixing of the particles over the Ioannina basin; this information would be extremely valuable to forecast air pollution episodes and provide tools to policy makers to reduce air pollution in the area and the relevant mortality and morbidity issues attributed to particulate matter (PM) exposure

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Summary

Introduction

Agricultural fires, and the use of wood as fuel for domestic heating during the winter season, are the major sources of the biomass burning (BB) particles [1,2,3]. Despite the severity of these air particulate pollution episodes occurring during winter-time, there has been a lack of knowledge of the spatio-temporal evolution of the vertical mixing of the particles over the Ioannina basin; this information would be extremely valuable to forecast air pollution episodes and provide tools to policy makers to reduce air pollution in the area and the relevant mortality and morbidity issues attributed to PM exposure To fulfill this lack of information, the lidar technique was applied during the PANACEA winter campaign (10 January 2020–7 February 2020) at Ioannina, as it is an ideal tool to monitor the spatio-temporal evolution of the atmospheric structure and the PM distribution with increased temporal (30–60 s) and spatial (7.5 m) resolution. It is located near Lake Pamvotis (coverage 19 km2) inside a basin surrounded

Location and Description of the NTUA Lidar System
Lidar Data Processing
Planetary Boundary Layer Height Calculation
Low-Cost Sensors
Aethalometer
Results and Discussion
Local Biomass Burning Aerosol
Dust Aerosol Mixtures
Conclusions

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