Observational investigations on air ions in the lower troposphere
Air ions are constantly generated throughout the atmosphere by natural ionising radiation and they participate in the formation and dynamic processes of atmospheric aerosol particles. Their flow in the atmosphere is the cause for the air conductivity. However, there is a gap in understanding how var...
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ftunivhelsihelda:oai:helda.helsinki.fi:10138/233895 2023-08-20T04:00:08+02:00 Observational investigations on air ions in the lower troposphere Chen, Xuemeng Swietlicki, Erik University of Helsinki, Faculty of Science, Department of Physics, Institute for Atmospheric and Earth System Research (INAR) Helsingin yliopisto, matemaattis-luonnontieteellinen tiedekunta, fysiikan laitos Helsingfors universitet, matematisk-naturvetenskapliga fakulteten, institutionen för fysik 2018-04-03T09:21:00Z application/pdf http://hdl.handle.net/10138/233895 eng eng Helsingin yliopisto Helsingfors universitet University of Helsinki URN:ISBN:978-952-7091-99-9 http://hdl.handle.net/10138/233895 URN:ISBN:978-952-7276-00-6 Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty. This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited. Publikationen är skyddad av upphovsrätten. Den får läsas och skrivas ut för personligt bruk. Användning i kommersiellt syfte är förbjuden. Text Doctoral dissertation (article-based) Artikkeliväitöskirja Artikelavhandling doctoralThesis 2018 ftunivhelsihelda 2023-07-28T06:10:26Z Air ions are constantly generated throughout the atmosphere by natural ionising radiation and they participate in the formation and dynamic processes of atmospheric aerosol particles. Their flow in the atmosphere is the cause for the air conductivity. However, there is a gap in understanding how variations in ionising radiation levels are reflected in air ion properties. Besides, observations related to air ions have been conducted at many sites around the globe, but the knowledge on features in air ions in vapour-limited environments is missing. The work in this thesis is dedicated to fill in these voids in knowledge related to air ions using the observational approach. Factors influencing natural radioactivity in the atmosphere in a boreal forest were identified at the Hyytiälä SMEAR II Station in Finland. We found that the diurnal and seasonal patterns in the natural ionising radiation level were mainly introduced by boundary layer dynamics as well as snow cover and soil conditions. Current instrumentations for measuring the number size distribution of air ions have a lower size limit of 0.8 nm in the Millikan mobility diameter. Based on our analysis, the concentrations of 0.8-1 nm ions were generally seen varying similarly to the natural ionising radiation level. We found a clear enhancement of ionising radiation on 0.8-1.7 nm ion production on atmospheric NPF event days but not on non-event days, which suggests that 0.8-1.7 nm ions undergo less dynamic modifications and are possibly formed over shorter time scale on NPF event days than on non-event days. To study features in air ions under conditions of limited vapours, the Concordia Station at Dome C, Antarctica, was chosen as the measurement site. Air ion processes were found to be active at the Concordia Station, including atmospheric new particle formation (NPF), ion production and loss in relation to cloud formation and wind-induced ion formation. Overall, these results advance our understanding on the ion processes in the atmosphere, which can assist ... Doctoral or Postdoctoral Thesis Antarc* Antarctica Helsingfors Universitet: HELDA – Helsingin yliopiston digitaalinen arkisto Concordia Station ENVELOPE(123.333,123.333,-75.100,-75.100) |
institution |
Open Polar |
collection |
Helsingfors Universitet: HELDA – Helsingin yliopiston digitaalinen arkisto |
op_collection_id |
ftunivhelsihelda |
language |
English |
description |
Air ions are constantly generated throughout the atmosphere by natural ionising radiation and they participate in the formation and dynamic processes of atmospheric aerosol particles. Their flow in the atmosphere is the cause for the air conductivity. However, there is a gap in understanding how variations in ionising radiation levels are reflected in air ion properties. Besides, observations related to air ions have been conducted at many sites around the globe, but the knowledge on features in air ions in vapour-limited environments is missing. The work in this thesis is dedicated to fill in these voids in knowledge related to air ions using the observational approach. Factors influencing natural radioactivity in the atmosphere in a boreal forest were identified at the Hyytiälä SMEAR II Station in Finland. We found that the diurnal and seasonal patterns in the natural ionising radiation level were mainly introduced by boundary layer dynamics as well as snow cover and soil conditions. Current instrumentations for measuring the number size distribution of air ions have a lower size limit of 0.8 nm in the Millikan mobility diameter. Based on our analysis, the concentrations of 0.8-1 nm ions were generally seen varying similarly to the natural ionising radiation level. We found a clear enhancement of ionising radiation on 0.8-1.7 nm ion production on atmospheric NPF event days but not on non-event days, which suggests that 0.8-1.7 nm ions undergo less dynamic modifications and are possibly formed over shorter time scale on NPF event days than on non-event days. To study features in air ions under conditions of limited vapours, the Concordia Station at Dome C, Antarctica, was chosen as the measurement site. Air ion processes were found to be active at the Concordia Station, including atmospheric new particle formation (NPF), ion production and loss in relation to cloud formation and wind-induced ion formation. Overall, these results advance our understanding on the ion processes in the atmosphere, which can assist ... |
author2 |
Swietlicki, Erik University of Helsinki, Faculty of Science, Department of Physics, Institute for Atmospheric and Earth System Research (INAR) Helsingin yliopisto, matemaattis-luonnontieteellinen tiedekunta, fysiikan laitos Helsingfors universitet, matematisk-naturvetenskapliga fakulteten, institutionen för fysik |
format |
Doctoral or Postdoctoral Thesis |
author |
Chen, Xuemeng |
spellingShingle |
Chen, Xuemeng Observational investigations on air ions in the lower troposphere |
author_facet |
Chen, Xuemeng |
author_sort |
Chen, Xuemeng |
title |
Observational investigations on air ions in the lower troposphere |
title_short |
Observational investigations on air ions in the lower troposphere |
title_full |
Observational investigations on air ions in the lower troposphere |
title_fullStr |
Observational investigations on air ions in the lower troposphere |
title_full_unstemmed |
Observational investigations on air ions in the lower troposphere |
title_sort |
observational investigations on air ions in the lower troposphere |
publisher |
Helsingin yliopisto |
publishDate |
2018 |
url |
http://hdl.handle.net/10138/233895 |
long_lat |
ENVELOPE(123.333,123.333,-75.100,-75.100) |
geographic |
Concordia Station |
geographic_facet |
Concordia Station |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_relation |
URN:ISBN:978-952-7091-99-9 http://hdl.handle.net/10138/233895 URN:ISBN:978-952-7276-00-6 |
op_rights |
Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty. This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited. Publikationen är skyddad av upphovsrätten. Den får läsas och skrivas ut för personligt bruk. Användning i kommersiellt syfte är förbjuden. |
_version_ |
1774716765896441856 |